News > Ask the Expert: Vitamins and supplements

Ask the Expert: Vitamins and supplements

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Good nutrition is an important part of caring for yourself after a breast cancer diagnosis. But eating right isn’t always easy. You may be wondering how certain vitamins and supplements could help you to feel, and be, healthier. Learning more about these substances, and how to take them safely, could help you manage treatment side effects and prevent recurrence.

In September, Living Beyond Breast Cancer expert Suzanne Dixon, MPH, MS, RD, answered your questions about how certain vitamins and supplements could increase your sense of well-being.

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Remember: we cannot provide diagnoses, medical consultations or specific treatment recommendations. This service is designed for educational and informational purposes only. The information is general in nature. For specific healthcare questions or concerns, consult your healthcare provider because treatment varies with individual circumstances. The content is not intended in any way to substitute for professional counseling or medical advice.

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What vitamins or supplements would be most helpful to someone who has been diagnosed with breast cancer?

There are no official guidelines on vitamins or dietary supplements that are right for all women diagnosed with breast cancer. This makes sense, because everyone is different, each person comes into a cancer diagnosis with his or her own nutritional background and dietary habits, and not all women will have the same treatment plan. However, there are some important nutrients that may need your attention.

Researchers have documented that as many as 80 percent of women newly diagnosed with breast cancer may be vitamin D deficient or insufficient. This is important to address, because studies suggest low vitamin D levels may be linked with more side effects during treatment, and worse outcomes for women after treatment.

Before you take supplements, talk to your doctor about getting a blood test, to ensure you actually need more vitamin D. If your blood levels are low, work with your doctor or dietitian on a vitamin D supplementation plan to bring levels back into a range that is normal. Finally, make sure you ask your doctor to retest your blood levels in 6 months to a year, to ensure that the supplements have corrected the deficiency.

Retesting after supplementing vitamin D is important, because different people can respond differently to vitamin D supplements. Some people need more vitamin D than others in order to bring blood levels into a range that is normal. It is important not to give excess vitamin D that isn't needed; on the other hand, you don't want to take supplements and never check blood levels again. Even after supplementing vitamin D, some people may still be deficient. These people simply may need more vitamin D than others to correct a deficiency.

Other nutrients of concern include calcium, vitamin K, and omega-3 and omega-9 fats. Calcium is critical for all women, but particularly for women who are at higher than average risk for bone loss. This includes women with a history of breast cancer. However, most women do not need to supplement the entire amount of calcium to meet the recommended dietary intake (RDA) for this mineral. For women up to age 50, the RDA is 1,000 mg of calcium per day. For women 50 years and older, the RDA is a little higher, at 1,200 mg per day. It is likely you are getting some calcium from your diet, even if you don’t eat dairy foods. Many foods are calcium fortified as well, and natural sources include green leafy vegetables, beans and some seeds and nuts.

As with vitamin D, there is a calcium “sweet spot.” It is not good to consume excess calcium, so work with a dietitian to figure out how much calcium you are getting from your diet. Then add in a supplement to make up the rest of what you need.

For example, if you are 53 years old, and you get around 600 mg of calcium from your diet (be sure to count calcium-fortified foods), you need an additional 600 mg from dietary supplements. For optimal absorption, choose a supplement that provides 300 mg per dose, and split the doses up, taking them at different times of the day. A supplement with magnesium is a good choice as well. Magnesium is calcium’s “right hand man” in terms of bone and cardiovascular health.

Vitamin K is critical to bone health as well, and getting enough is important for your heart too. Green leafy vegetables are the ideal way to get more vitamin K, because in addition to K, they also provide hundreds of other healthful “cancer-fighting” nutrients, called phytonutrients. Phytonutrients aren’t vitamins or minerals, but they are critical to good health. Many studies support that getting more of these plant nutrients into your diet can reduce cancer risk. Some of the phytonutrients in the green leafy vegetables, for example, help the body process estrogen more effectively, which is believed to be one of the ways through which these foods help decrease breast cancer risk.

When it comes to omega-3 and omega-9 fats, most of us don’t get enough! Omega-3 fats are found in cold water fatty fish, such as salmon, and in nuts and seeds. The best source of omega-9 fats is olive oil; there is ample research supporting that people who eat plenty of olive oil, such as those following a Mediterranean diet, have lower risk of breast, and many other types of cancer as well.

Is it better to try to get vitamins through the food I eat? Are there certain vitamins that are more important to get via food and others that are more OK to get in supplements?

It is nearly always better to obtain vitamins and minerals from the foods you eat, but even so, some people simply don’t eat enough of certain foods to meet their nutritional needs. For example, vitamin D is critical to health, yet many adults fall short of optimal intake, because vitamin D is only found in a few foods. Also of concern is that breast cancer survivors often have low levels of vitamin D, and may need supplements to address this potential deficiency.

Vitamin D occurs naturally in fatty fish, but most people eat that just a few times per month. Vitamin D-fortified milk can contribute to your intake, but if you don’t have several servings per day, you won’t meet your vitamin D needs from dairy alone. For this reason, vitamin D is one nutrient that may provide health benefits if taken as a supplement. One new way to get more vitamin D is to eat mushrooms specially grown to produce vitamin D. That’s something humans have in common with mushrooms — both produce vitamin D when exposed to sunlight. But most mushrooms are grown in the dark, so you only get vitamin D if the mushrooms are exposed to light periodically to produce vitamin D. Packaged mushrooms with vitamin D will indicate this on the label.

For women at risk of bone loss, calcium is another key nutrient that may require supplementing to reach the levels required for good health.  For more information about vitamin D and calcium, see the answer to question #1.

Other than vitamin D and calcium, most people won’t come up short on vitamins and minerals, as long as they eat a well-rounded diet, with plenty of unprocessed whole foods, including vegetables, nuts and seeds, fruit, whole grains, and lean protein, such as beans, peas, lean meats, chicken and fish. These are the true nutritional powerhouses, because they provide not only vitamins and minerals, but also thousands of other substances that contribute to good health. Eating more of these substances, called phytonutrients, is linked with reduced risk of cancer, heart disease, diabetes, hypertension, and other chronic conditions.

But there’s a catch: Taking phytonutrients as dietary supplements generally is not linked with improved health. In some cases, taking mega-doses of phytonutrients may even increase cancer risk. Health experts aren’t sure why this is the case, but one important concept to consider is synergy. Synergy refers to the interaction or cooperation of two or more substances to produce a combined effect that is greater than the sum of each of the separate effects. These phytonutrients seem to work best when we eat them as they occur in nature, in their infinite variety, in an infinite number of combinations and amounts in the plant foods we eat.

What can you tell me about soy (especially soy protein isolate that is in high quantities in nutritional bars) for people with estrogen receptor-positive breast cancer? I have heard different things about whether soy is safe.

Soy is one of the most confusing nutrition-related topics for women with a history of breast cancer. This is unfortunate, because it doesn’t need to be confusing! Confusion about soy arises from the term “phytoestrogens.” Some soy nutrients, called isoflavones, look a bit like the estrogen found in a woman’s body, in terms of chemical make up. This is where the term phytoestrogen originated. However, phytoestrogens are not the same thing as female estrogens. Soy foods do not contain estrogen.

Several large, human studies — in which thousands of women have been followed for many years — consistently show that compared with women who do not eat soy, women who regularly eat soy have lower breast cancer risk. Some of these studies also suggest that breast cancer survivors who consume soy foods have a lower risk of breast cancer recurrence compared with survivors who avoid soy.

These studies have been conducted in both Asian and U.S. populations. This is important because soy has long been a part of many Asian cuisines, but it is a relatively new introduction to the American diet. These studies also have included women with estrogen receptor-positive and estrogen receptor-negative breast cancer, and women taking tamoxifen and not taking tamoxifen. In all cases, women who eat more soy foods appear to have a decreased risk of breast cancer and reduced risk of breast cancer recurrence.

These studies are observational. This means researchers collect diet information from women, then follow them for many years to see who gets breast cancer. In an observational study, it is always possible that the true connection with reduced breast cancer risk is not soy, but something else that is related to eating soy.

For example, women who eat soy foods also may eat less fried food and more vegetables. They may exercise more and maintain a healthier body weight. They may drink less alcohol and smoke less. Any one of these other things could be the reason why soy-eating women have lower breast cancer risk. Researchers control for these other factors with statistics, but we can never know for sure if there is some unknown factor that was not accounted for.

This means observational studies can't conclusively prove that soy protects against breast cancer. But these studies are reassuring in affirming that soy foods do not increase breast cancer risk. They point toward a protective effect of soy on breast health, regardless of other lifestyle and diet choices.

There are also soy “feeding” studies, in which women provide breast tissue and blood samples prior to adding soy into the diet, and provide samples again after eating soy for a period of time. In this way, researchers can measure the direct effects of eating soy on breast tissue and hormone levels. None of these studies have shown that eating soy causes changes that are linked with cancer. Soy does not increase breast cell proliferation or breast density, both of which are breast cancer risk factors. Soy does not alter hormone levels in a negative way. Some studies suggest eating soy can decrease levels of estrogen in a woman’s body.

Based on all of this evidence, the current consensus among health experts who study soy is that breast cancer survivors can safely eat these foods. Emerging research suggests that soy foods may decrease the likelihood of breast cancer recurrence in women with a history of the disease.

Most health experts agree that the evidence is not strong enough to recommend that all women with a history of breast cancer eat more soy. However, soy foods do appear to be safe, and possibly beneficial for female breast cancer survivors.

As a final note, consider that soy foods are the healthiest option. Soy dietary supplements are not proven to support health in the same way as whole soy foods. If you’re a woman concerned about breast health and you like soy, stick to healthy, whole soy foods, such as tofu, tempeh, soymilk and edamame. The occasional soy protein bar or snack food is fine, but as with all plant foods, less processed is better. It’s best to avoid soy pills and isoflavone-enriched powders.

The most important thing when it comes to soy is to let go of the fear. You should feel confident in whatever choice you make about soy foods. Eat these foods if you enjoy them, or skip them altogether if soy is not to your liking.

I have a friend who went through breast cancer treatment 7 to 8 years ago and her nutritionist told her to avoid multivitamins and antioxidant foods. They said those substances might "protect" or “feed” the cancer cells that chemo was trying to kill. Now I am the one going through chemo and my nutritionist says that's not true. What is the current research on this issue? I don't want to take vitamins now only to learn later that the experts have changed their minds again and I shouldn't have taken them.

Nutrition science is like all science; the evidence accumulates slowly over the years, and sometimes, new research contradicts older research. It takes a lot of time, and many studies to give us the clearest picture about how our diet, different foods and nutrients affect health. And even if we have research on a nutrient and how it affects health in the general population, these results may not apply to someone who is going through cancer treatment. For all of these reasons, many people, including people being treated for cancer, often feel that they receive conflicting nutrition advice.

The current thinking on vitamins and antioxidants is that people should not take high doses of these nutrients if they are currently undergoing cancer treatment. It is safe to take a multivitamin that provides up to five times (500 percent of) the recommended dietary allowance (RDA) for vitamins and minerals, but it is best to avoid “mega-dose” multivitamins that provide more than this.

The main reason for limiting mega-doses of antioxidants and vitamins is not due to known harms they can cause during cancer treatment. For most cancer cases, we simply don’t know if these supplements are safe. There have not been enough studies to draw conclusions about who should or should not take high doses of vitamins and antioxidants during treatment. The concern that these nutrients will “protect” or “feed” the cancer is not proven. Your current nutritionist is right about that. However, we just don’t know enough to make specific recommendations on which nutrients to supplement or not supplement during breast cancer treatment.

We have some observational studies which suggest these supplements are not harmful, but observational studies don’t prove cause and effect. It’s possible that the people who choose to take dietary supplements are healthier for other reasons.

Given all of this uncertainty, it makes sense to avoid large doses of most vitamins and antioxidant nutrients during breast cancer treatment. There is no reason to avoid foods that provide antioxidants, vitamins, minerals and other phytonutrients. The research supports that these foods are healthy, before, during and after cancer treatment, so don’t avoid vegetables, fruit, nuts, seeds, whole grains and legumes. These are all good choices, as long as you are not losing a lot of weight or struggling to get enough to eat during treatment.

Can I take biotin while on tamoxifen?

There are no reported interactions between biotin and tamoxifen. It is likely safe for you to use biotin while you are taking tamoxifen. However, to be on the safe side, take these items at separate times of the day, or at least an hour or two apart from one another. Some things may not cause “systemic” interactions in the body in terms of toxicity or how a medication is metabolized. But it may interact when in direct contact in the gastrointestinal (GI) tract. To avoid any potential interactions as they pass through your GI tract, simply take them separately.

I had my last chemo treatment a year ago, and am still experiencing brittle nails. Is it safe to take a product called Biosil? It is in a liquid form and you put several drops into water or juice. My hair is fine but I can't seem to strengthen my nails.

Biosil contains silicon and choline, which are believed to help strengthen hair, nails and bones. There are no listed drug interactions for silicon or choline, however, you may want to avoid taking Biosil within a couple of hours (before and after) of taking other oral medications. Silica is a mineral and it may bind other medications in the gut, decreasing absorption.

Also, there are case reports of kidney stones in some people taking silica-based antacids long-term. The amount of silicon in antacids is likely much higher than what is found in Biosil, so this probably will not be an issue, especially if you only plan to use Biosil on a short-term basis. However, if you have a history of kidney stones, you may want to avoid products that contain silicon.

What is a good amount of vitamin C to shoot for daily? Should someone with breast cancer be getting more or less vitamin C than other people?

There is no research evidence to support that a woman with breast cancer would need extra vitamin C, but a healthy diet will provide well beyond the basic recommended dietary allowance (RDA) for this nutrient. The current RDA for vitamin C is 75 mg per day for women and 90 mg per day for men. There is some evidence that smokers require more vitamin C than non-smokers, and it is recommended that people who smoke get an additional 35 mg of vitamin C per day for best health. Of course, to truly improve health, quitting smoking is the single best thing a current smoker can do! But assuming you don’t smoke, 75 mg per day is a good place to start.

According to the National Institutes of Health (NIH) Fact Sheet on Vitamin C, adult women get an average of 84 mg of vitamin C per day. This means that if your diet is varied and healthy, and includes plenty of vegetables and fruit — the best source of vitamin C — you are easily meeting your basic vitamin C needs. It’s also worth noting that if you eat a healthy plant-based diet, which is recommended as one of the best ways to get the most “cancer risk reduction benefit” from your food, you will get a lot of vitamin C as a side effect. According to the NIH, consuming five varied servings of fruits and vegetables a day can provide more than 200 mg of vitamin C daily.

It’s best not to take high doses of vitamin C from dietary supplements if you are currently undergoing cancer treatment. This is because the research isn’t clear on whether large doses of vitamin C are helpful, harmful, or neutral during cancer care. But if you want to take some vitamin C from a dietary supplement, just to make sure you’re meeting your basic needs, stick to a lower dose product. Choose a dietary supplement that provides no more than 200 mg of vitamin C per day.

In terms of food, citrus fruit and bell peppers are great sources. Just one-half cup of red bell pepper provides 95 mg of vitamin C, or about 130 percent of the RDA. An orange will give you around 70 mg. A half cup of cooked broccoli will provide 50 mg of vitamin C, which meets two-thirds of your daily needs.

Heat and light can break down vitamin C, so eating some fruit and vegetables raw is a good idea to ensure you are getting the full vitamin C “bang for your buck” from these foods. When you do cook, “lighter” cooking methods, such as steaming, sautéing, stir-frying and even microwaving preserve most of the vitamin C. Cook until the foods are brightly colored and still retain a little crispness, and you’ll keep most of the vitamin C intact.

Are there certain vitamins or supplements that would help with side effects from aromatase inhibitors?

There is some evidence that supplementing vitamin D, especially if you are deficient in this nutrient, may help reduce the aches and pains associated with taking aromatase inhibitors. One study found that high dose supplementation of 50,000 IU of vitamin D once per week for 8 to 16 weeks, followed by 50,000 IU of vitamin D once per month for an additional 2 to 4 months, significantly reduced bone and muscle pain in women taking aromatase inhibitors. The effect was greatest in the women who were most deficient in vitamin D to begin with. This makes sense, because if being low in vitamin D worsens the side effects of aromatase inhibitors, then women who have the lowest blood levels of vitamin D are likely to benefit the most from taking vitamin D supplements.

Another study found that getting the blood level of vitamin D (25-hydroxy vitamin D) up to a target concentration of 40 ng/ml (nanograms per milliliter) will best prevent aromatase inhibitor-related pain. Ask your doctor for a vitamin D blood test, and if your level is low, you will need to take vitamin D supplements. You can work with your doctor or dietitian on a vitamin D supplementation plan to bring levels back into the normal range. Finally, make sure you ask your doctor to retest your blood levels in 6 months to a year, to ensure that the supplements have corrected the deficiency.

The other reason to work with your doctor or dietitian to determine the best vitamin D supplement plan for you is that people respond differently to vitamin D supplements. Some people need much higher doses of vitamin D for a longer period of time to bring blood levels into the normal range. But other people don’t need these high levels to correct deficiency. It’s not a good idea to take a lot more vitamin D than you need, so testing and retesting your blood levels is the best way to ensure you’re hitting the right dose for you.

Once your blood vitamin D levels are in the normal range, you may need to continue to supplement at a dose that is several times the recommended dietary allowance (RDA) for the long-term, to prevent yourself from becoming deficient again. The RDA is 600 IU per day for women up to age 70, and 800 IU per day after age 70.

For vitamin D, “tolerable upper limit,” which is the maximum amount of a nutrient that is considered safe to take on a daily basis, is 4,000 IU. It’s OK to take higher doses than 4,000 IU per day for a few weeks to a few months, in order to correct a deficiency. However, once you have confirmed that your vitamin D levels are in the normal range, you should not take more than 4,000 IU of vitamin D per day on an ongoing basis.

If hot flashes due to aromatase inhibitors are a big problem for you, talk to your doctor about options for better managing this side effect. There may be non-hormonal medications your doctor can prescribe to help you with this. If your doctor does not want to add any additional medications into your cancer risk management plan, consider acupuncture, meditation and yoga. It may sound far-fetched, but all three of these self-care and wellness options have evidence that they can improve quality of life in breast cancer survivors who are suffering from severe hot flashes. These options probably won’t completely get rid of your hot flashes, but they can make them less intense, less frequent and more manageable. Plus, it never hurts to add anything into your self-care plan that helps with stress management.

I've recently added B12 liquid vitamins daily to my medicine intake in hopes of helping my metabolism. Will this hurt or help? My estrogen blockers are wrecking my weight.

Vitamin B12 is considered safe, even when taken at doses of up to 10 times the recommended dietary allowance (RDA). But if you are not deficient in vitamin B12, taking extra will not improve your metabolism. There aren’t any vitamins or minerals that will help speed up metabolism, unless you have a nutrient deficiency. For most of us, nutrient deficiencies aren’t all that common.

Unfortunately, one of the side effects of medications that block estrogen receptors (tamoxifen) or inhibit estrogen production in the body (aromatase inhibitors) is weight gain. No one is exactly sure why this happens, but the effect is real. Some researchers who study this issue have found that loss of lean body mass can worsen weight gain during and after breast cancer treatment.

The main place you find lean body mass is skeletal muscle, which includes the large muscles in your body, such as the muscles in your abdomen, thighs, back and chest. Muscle responds to resistance training, so if you add this into your regular fitness routine, you can rebuild some of that lost strength.

Resistance training, also known as strength training, has been shown to help prevent, or at least minimize the weight gain associated with breast cancer treatment. And you don’t need to join a gym to get the benefit. Even using the stretchy rubber “thera-bands” that you find in a physical therapist’s office is enough to rebuild lost muscle tissue. Standing on one end of a band and doing bicep curls, looping a band around your knees and doing walking lunges (be careful with balance, and avoid this if balance is an issue for you!), push-ups or knee push-ups, and “chair dips” all are proven ways to rebuild strength.

The reason this works to help prevent weight gain and even spur modest weight loss for some women is because muscle tissue burns more calories than almost any other tissue in the body (the brain burns the most). When you build muscle, you automatically increase your metabolism. More muscle means more calories burned, even when sitting at rest.

Finally, consider an appointment with a registered dietitian who specializes in oncology nutrition. Even if you have to pay out of pocket, it can be worth the small investment to get some basic pointers on how to structure your diet to feel full and satisfied, but not eat more calories than you need. Nobody likes to “go on a diet,” and that’s another reason to consult a dietitian. He or she can help you develop a life-long healthy eating pattern that you can stick with, which will help you avoid ups and downs in your weight over time.

I would like to try pure aloe juice as a supplement but am concerned that there may be estrogen produced by the plant (I have estrogen receptor-positive, stage IV breast cancer). Is this something to worry about?

Aloe juice is considered safe when taken in small doses, but you should be sure to use a product that is certified “latex-free.” The aloe plant produces two main substances – gel and latex. The gel is generally considered safe to take orally, but the latex is not.

Aloe latex can irritate your stomach and intestines, and it has a strong laxative effect, leading to diarrhea in many people. Additionally, aloe latex can cause kidney and liver damage and electrolyte abnormalities, such as low potassium levels in the body. These are very serious side effects.

If you want to take aloe gel, start with a small does, such as an ounce per day. You want to make sure you don’t have any negative reactions to aloe before you take more than this. There isn’t any good evidence that aloe gel will have estrogenic effects in the body, and it may even help regulate estrogen metabolism favorably by lowering cholesterol levels in the body.

It turns out that cholesterol is a precursor to estrogen. That means the body uses cholesterol to manufacture estrogen. If you take aloe gel, it can pull cholesterol out of your gastrointestinal tract as it passes through; you then excrete the excess cholesterol in your stool. But this effect is likely small, so aloe gel should not be used in place of other medications you are taking to lower cholesterol or block estrogen.

Aloe gel is often suggested as a remedy for other conditions as well, including heartburn, canker sores, diabetes, gum disease (gingivitis), high cholesterol and ulcerative colitis. The evidence on these uses is mixed, so don’t use aloe gel in place of other medications without talking to your doctor or dietitian first.

Keep in mind that many herbal and dietary supplement products, including aloe gel, can interact in dangerous ways with other medications. For this reason, you should make sure you aren’t taking anything else that will interact with aloe. Consider the following points carefully before you begin using aloe gel:

  • Avoid taking aloe gel within a couple of hours (before and after) of taking other oral medications. Aloe gel may bind other medications in the gastrointestinal tract, decreasing absorption.
  • Aloe gel should not be used by women who are pregnant or lactating, and should never be given to children under age 12.
  • There are reports in the medical literature that aloe gel may lower blood sugar (glucose) levels. This is not considered a problem for people with normal metabolism, but you should not use aloe gel if you have hypoglycemia, diabetes or are under treatment for blood sugar problems.
  • Because aloe gel may lower blood sugar levels and have mild blood thinning effects, it should be stopped for at least 2 weeks prior to surgery.
  • Aloe gel can interact with the following medications, so do not take aloe gel if you use any of these medications:
    • Medications to treat diabetes, including oral medications and insulin
    • Sevoflurane (Ultane)  (a general anesthetic used for surgery)
    • Blood thinning medications, such as warfarin (Coumadin), dabigatran (Pradaxa), rivaroxaban (Xarelto), and apixaban (Eliquis)
    • Laxatives
    • Diuretics (“water pills”), such as chlorothiazide (Diuril), chlorthalidone (Thalitone), furosemide (Lasix) and hydrochlorothiazide (HCTZ, HydroDIURIL, Microzide)

As long as you are not taking any of these medications and don’t have other reasons to avoid aloe gel, it should be safe for you to use this dietary supplement, and there currently is no reason to believe aloe has significant estrogenic actions in the body.

Can taking curcumin/turmeric help reduce inflammation in a breast cancer survivor? Is it safe to take during active treatment? How much should be taken daily?

Curcumin is being studied extensively for its potential uses in cancer care. Curcumin is one of the main substances found in turmeric, which is the bright orange spice commonly found in Indian curry dishes. Turmeric is a rhizome or “root-” like spice, and looks a lot like ginger in its raw form. Think of ginger, only orange in color!

Turmeric has a long history of safe use as a culinary spice, and even when eaten in large quantities on a regular basis, it appears to be well-tolerated. Curcumin is one active ingredient in turmeric, and curcumin is being studied for safety and efficacy for a wide variety of conditions and diseases.

Curcumin has documented anti-inflammatory activity in the body and research suggests that curcumin may help reduce the joint pain and inflammation associated with osteoarthritis. This is one of the conditions for which the best research evidence exists. There are hints that curcumin may help with other health conditions, including eye and skin inflammation, rashes, heart disease, inflammatory bowel disease (Crohn’s disease and ulcerative colitis), diabetes, gum disease, stomach ulcers, irritable bowel syndrome and rheumatoid arthritis. At this time, the evidence is insufficient to draw any firm conclusions about whether curcumin really is effective for managing or treating these conditions. It’s frustrating to hear this, but we are at the stage of “more research is needed,” before we can recommend curcumin for these health conditions.

Small research studies suggest curcumin is safe to take during cancer care, although you should always discuss the use of dietary supplements and over-the-counter medications with your cancer care team before you try these products.

One small phase I study of 14 women with advanced and metastatic breast cancer suggested curcumin is safe to use in combination with docetaxel chemotherapy. In this study, the maximum dose of curcumin that was tolerated was 8,000 mg (8 grams) per day. Beyond this dose, the women in the study experienced side effects that caused them to stop taking curcumin. From this research, the study authors concluded that 6,000 mg per day was a reasonable recommended dose. However, for this study, this dose was only given for seven days at a time, along with the standard dose of docetaxel chemotherapy. None of the women took curcumin continuously for the entire duration of the study, and most studies (non-cancer) use much lower doses of curcumin daily.

One other study randomly assigned 80 people with a variety of solid tumors to receive 180 mg of curcumin per day, or to receive a placebo (no curcumin) for 8 weeks during cancer chemotherapy treatment. The people who received the curcumin supplement had significantly improved quality of life and less systemic inflammation compared with those who took the placebo pill.

Another study randomly assigned 30 women who were undergoing radiation therapy for breast cancer to receive 2 grams of curcumin taken three times per day (total dose of 6 grams daily) or to receive a placebo (no curcumin) for the duration of radiation treatment. The women who received the curcumin had significantly less radiation dermatitis compared with those who took the placebo pill. The biggest effect seemed to be at preventing a type of radiation dermatitis called moist desquamation. Only 28.6 percent of the women in the curcumin group experienced moist desquamation vs. 87.5 percent of the women in the placebo group. For this particular side effect, curcumin seemed to be quite effective in this small study.

One thing to consider is that some holistic healthcare providers, such as naturopathic doctors and herbalists, feel that curcumin should be avoided by women with breast cancer because it may have estrogenic effects in the body. But one placebo-controlled study of 40 healthy premenopausal women found that herbal supplements containing curcumin had no substantial effects on measures of estrogen when given over five menstrual cycles. There were no changes in total estradiol, free estradiol, or sex hormone-binding globulin compared with placebo (no curcumin or active ingredients).

As a final note, keep in mind that many herbal and dietary supplement products, including curcumin, can interact in dangerous ways with other medications, or may be contraindicated for use in people with specific health conditions.

For this reason, you should make sure you aren’t taking anything else that will interact with curcumin or have any conditions that may be worsened by taking curcumin. Consider the following points carefully before you begin using curcumin:

  • Avoid taking curcumin within a couple of hours (before and after) of taking other oral medications. Curcumin may interfere with other medications in the gastrointestinal tract.
  • Curcumin should not be used by women who are pregnant or lactating.
  • There are reports in the medical literature that curcumin may lower blood sugar (glucose) levels. This is not considered a problem for people with normal metabolism, but you should not use curcumin if you have hypoglycemia, diabetes or are under treatment for blood sugar problems.
  • Because curcumin may lower blood sugar levels and have mild blood thinning effects, it should be stopped for at least 2 weeks prior to surgery.
  • People with gallbladder problems, gallbladder stones, or chronic heartburn should not use curcumin. It may worsen these conditions.
  • Curcumin can interact with the following medications, so do not take curcumin if you use any of these medications:
    • Medications to treat diabetes, including oral medications and insulin
    • Blood thinning medications, such as warfarin (Coumadin), dabigatran (Pradaxa), rivaroxaban (Xarelto) and apixaban (Eliquis)
    • Iron pills. If you are taking iron to address iron-deficiency anemia, curcumin may inhibit the absorption of iron.

In summary, curcumin appears safe to use during cancer treatment, but ask your doctor first to make sure it’s OK. For continuous use, stick to lower doses, and do not exceed a daily dose of 6 grams per day. As long as you are not taking any medications that could interact with curcumin and don’t have other reasons to avoid curcumin, it should be safe for you to use this dietary supplement. There currently is no reason to believe curcumin has significant estrogenic actions in the body.

Is taking selenium and CoQ10 helpful for women with breast cancer?

Selenium is an essential mineral and it is considered a “trace element.” This refers to the fact that we need extremely small, or “trace,” quantities of this nutrient in our diet for good health. The recommended dietary allowance (RDA) for selenium is 55 micrograms (mcg). This is a much smaller quantity when compared with other essential minerals, such as calcium and iron, which our bodies need in milligram amounts.

One small study suggested that selenium supplements may decrease the risk of breast cancer in women with the BRCA1 mutation. But this was a very short-term study, and upon longer follow-up it appears that the protective effect of selenium disappeared.

There aren’t other good studies of selenium supplements and breast cancer, but there are large-scale, double-blinded, controlled clinical trials looking at selenium supplementation and prostate cancer risk. These studies show that when it comes to selenium, more is not better.

Even for men who began the study with low blood levels of selenium, a selenium supplement did not lower cancer risk. And for men with higher baseline selenium levels, adding a selenium supplement increased the risk of high-grade, or more aggressive, prostate cancer. Also of concern is that for men who have been diagnosed with prostate cancer, adding a selenium supplement to their diet appears to increase the risk of dying of prostate cancer.

Taking all of this into consideration, it appears that taking a selenium supplement is not likely to provide a benefit to breast cancer patients. If the situation with prostate cancer is any indication, these supplements may be more harmful than beneficial.

If you are concerned you may not be getting enough selenium, there is a simple solution: Turn to food. While studies of selenium supplements suggest they may cause more harm than good, there is consistent agreement among the experts that getting selenium from the diet will not raise cancer risk. Dietary selenium is very safe. Supplemental selenium may not be.

The easiest way to get selenium from your food is to eat one or two Brazil nuts every day. Just one single Brazil nut provides 78 micrograms of selenium! That’s more than the RDA for selenium. But because Brazil nuts are such a rich source of selenium, don’t overdo it. If you ate a handful of Brazil nuts every single day, this would almost be like taking a selenium supplement. So stick to food, and just pop a Brazil nut or two in your mouth daily to meet your selenium needs safely.

Regarding Coenzyme Q10, or CoQ10, there may be some benefit for women with breast cancer. Some evidence suggests CoQ10 may protect the heart against damage (called cardiomyopathy) from the chemotherapy medication doxorubicin (Adriamycin). These studies are small and observational (not controlled trials), so more research needs to be done to confirm this potential benefit.

Even with the incomplete evidence, it appears that CoQ10 is safe and well-tolerated, and is unlikely to cause harm if you’d like to take it. You should always ask your doctor or dietitian about any dietary supplements or over-the-counter medications you want to use, especially if you are receiving active cancer treatment. CoQ10 is an antioxidant, and some oncologists do not want patients to take antioxidants during cancer treatment.

Assuming you get the OK from your medical care team, typical recommended doses of CoQ10 range from 60 to 200 mg per day. Also of interest is that CoQ10 supplements often are recommended for people who are taking statin medications to treat high cholesterol. These medications can decrease CoQ10 levels in the body and taking a supplement seems to help prevent this issue. CoQ10 supplements also may lessen the likelihood of side effects from statins.

There is a small amount of evidence that CoQ10 may lower blood pressure in people with hypertension and help manage heart failure, lessen the severity of nerve damage and its associated pain due to diabetes, help manage migraine headaches, lessen the likelihood of a second heart attack when taken for up to a year after a first heart attack, and slow down the progression of Parkinson’s disease.

Keep in mind that many herbal and dietary supplement products, including CoQ10, can interact in dangerous ways with other medications. These products also can have their own side effects. For this reason, you should make sure you aren’t taking anything else that will interact with CoQ10. Consider the following points carefully before you begin using a CoQ10 supplement:

  • CoQ10 dietary supplements are generally very well tolerated, but some people do experience nausea, stomach upset, loss of appetite or diarrhea when taking it.
  • Although rare, CoQ10 can cause allergic skin rashes in some people, so be alert to changes in your skin if you are taking CoQ10 supplements.
  • CoQ10 may lower blood pressure, so use with caution if you are being treated for either high or low blood pressure.
  • CoQ10 may have mild blood thinning effects, so do not take it with other medications that are used to manage blood clotting issues.
  • CoQ10 may lower blood pressure and have mild blood thinning effects, so it should be stopped for at least 2 weeks prior to surgery.
  • CoQ10 can interact with the following medications, so do not take CoQ10 if you use any of these medications:
    • Blood thinning medications, such as warfarin (Coumadin), dabigatran (Pradaxa), rivaroxaban (Xarelto) and apixaban (Eliquis)
    • Blood pressure lowering medications, including diuretics, such as captopril (Capoten), enalapril (Vasotec), losartan (Cozaar), valsartan (Diovan), diltiazem (Cardizem), Amlodipine (Norvasc), hydrochlorothiazide (HydroDiuril) and furosemide (Lasix).
    • Chemotherapy: Small studies to date do not indicate that CoQ10 will interfere with chemotherapy medications, but concern remains that it could cause problems due to its antioxidant activity. Always ask your doctor or dietitian before using any dietary supplement during cancer treatment.

As long as you are not taking any of these medications and don’t have other reasons to avoid CoQ10, it should be safe for you to use this dietary supplement and there currently is no reason to believe CoQ10 will cause health issues when taken at recommended doses.

Can I take Raw Meal as a breakfast substitute when I'm finished with radiation and am on an aromatase inhibitor?

Raw Meal is a meal replacement product and some people find it helpful because of its convenience and ease of use. There is no reason you would need to avoid Raw Meal while taking an aromatase inhibitor. If you feel this product helps you move toward a healthy diet, it should be safe for you to use it.

Would zinc supplements be helpful in supporting immune health in a breast cancer patient/survivor?

Zinc deficiency is rare for most people who are eating a regular diet. And the evidence is clear that if you do not have a zinc deficiency, adding extra zinc into the diet will not improve immune function. The other issue with zinc supplements is that they can lead to copper deficiency if used long-term. Both copper and zinc are absorbed in the same way in the gastrointestinal tract, but zinc “out competes” copper and is more readily absorbed. This can lead to a failure to absorb enough copper, and eventually a copper deficiency.

If you are concerned that you aren’t getting enough zinc, ask your doctor for a zinc blood test, although be aware that your insurance may not cover it. If you don’t have the ability to get a blood test, try getting more zinc through food. The National Institutes of Health has a good education sheet on zinc, and provides a list of zinc-rich foods.

If you do decide to take a zinc supplement, ask your doctor or dietitian to recommend a good quality product. Be sure any supplement you do use provides no more than 1 to 2 times (100-200 percent) the recommended dietary allowance (RDA) for zinc, to avoid the issue with copper deficiency.

The one exception for when taking more zinc may be helpful is if you have a wound that will not heal properly. For some cancer patients, wounds from surgery don’t heal well, and evidence suggests that a combination of zinc, vitamin C and arginine (an amino acid, or “building block” of protein) will speed wound healing. If this is an issue for you, ask your doctor or dietitian to recommend a wound healing formula that will provide the right amounts of zinc, vitamin C and arginine.

I take paclitaxel and experience neuropathy as a side effect. Can glutamine powder or any other supplements help prevent neuropathy? If so, should people start taking it before they begin taking a medicine that can cause neuropathy?

The research on using glutamine powder for neuropathy has produced mixed results. This is likely due to some of the studies using doses of glutamine that are too low to provide benefit, or to many patients in the study failing to take the glutamine supplements as prescribed.

The studies that do show a benefit suggest it is better to prevent neuropathy by taking glutamine before it develops, rather than to try to “cure” neuropathy with glutamine after you have it. But even if you already have neuropathy, you can give glutamine a try. Studies in animals and humans support that glutamine is safe for most people to take and does not have a high potential for interfering with chemotherapy medications. Some animal studies suggest it may improve the effectiveness of chemotherapy, but more research is needed before any firm conclusions can be drawn.

If you do want to try glutamine, the recommended therapeutic dose is 10 grams of glutamine, taken 3 times per day, for a total dose of 30 grams daily. Glutamine is generally tasteless and odorless, and can be added to cold or room temperature foods or drinks. Do not mix glutamine with hot liquids, as this breaks down the active ingredient. Most people simply mix it in room temperature water or into yogurt, and get it into the diet this way.

The most cost effective way to order glutamine powder is to order it online, in a 1-kilogram container. Glutamine in health food stores tends to be very expensive, even for the same products that you would buy online.

Other supplements that are being studied for their potential to prevent or treat neuropathy include alpha lipoic acid and Coenzyme Q10. Alpha lipoic acid does seem to help with diabetic neuropathy, although this is somewhat different from chemotherapy-induced neuropathy, so it isn’t yet known if it will be helpful for cancer patients. Research on CoQ10 and neuropathy are in the early stages.

You should always ask your doctor or dietitian about any dietary supplements or over-the-counter medications you want to use, especially if you are receiving active cancer treatment. Alpha lipoic acid and CoQ10 do have antioxidant activity, and some oncologists do not want patients to take antioxidants during cancer treatment.

Are there any vitamins or supplements that you would strongly suggest a person with breast cancer DOESN’T take?

I advise against taking dietary supplements that may have strong effects on hormone levels in the body. This includes DHEA, red clover and licorice. Any dietary supplement that is labeled to “naturally support a woman’s hormones” or as a “natural menopause” option are also things that I advise against using for anyone with a history of breast cancer.

For women with breast cancer, whole soy foods are safe and healthy to include in the diet and several studies suggest women with breast cancer who eat soy foods have a lower risk of breast cancer recurrence compared with women who do not eat these foods. But concentrated soy supplements are not well studied, so I advise women to stick with foods — tempeh, miso, tofu, edamame, soy milk — and to avoid soy-based dietary supplements.

Also consider what types of cancer treatments you are receiving. Some dietary supplements may be fine for some patients, but may need to be avoided during treatment for other patients. For example, there is some evidence that the dietary supplements berberine and quercetin may interact with taxane chemotherapy. For someone on taxane medications, these would need to be avoided. For a woman who is not taking these drugs, these supplements may be perfectly safe.

The most important thing is to discuss your use of dietary supplements with your doctor or dietitian. These people will know your full medical history and your planned course of treatment. They will be able to advise you best on which dietary supplements may or may not be safe for you to use.

I think of my essential oils as supplements. I've been told that using a topical blend of frankincense, sandalwood and lemon may help lower the risk of recurrence. What are your thoughts on these, or other possibilities?

Essential oils have been used in a variety of cultures for thousands of years, but they are fairly new in the cancer care arena. There are no studies that have examined how the use of essential oils may affect cancer risk, or risk of recurrence in people who have had the disease. Some companies that manufacture and sell essential oils claim that these products can “prevent” or “beat” cancer, but these claims are not supported by scientific evidence in humans.

These claims of effectiveness against cancer are based largely on what is known as anecdotal evidence, plus some laboratory studies in cells (in a petri dish or test tube). Unfortunately, anecdotal reports by people cannot be verified, so there is no way to determine if the person making the report is an actual patient who had a positive experience with the essential oil. Cell studies are an important starting point in cancer research, but they are not a good way to know if the therapy being tested will actually work in humans. Cancer cells can behave very differently in a test tube than they would behave inside of a human body.

There is some good news on essential oils. Research does support that they may make people feel better in other ways. There have been some studies of essential oil use in people with cancer. Many of these studies failed to find a benefit of aromatherapy in cancer treatment. But some of the research suggested essential oils may lessen anxiety and blood pressure in some people. You can read more about this research in a free online report by the National Cancer Institute (NCI).

Even though we may not have hard evidence to support or refute claims of “anti-cancer” benefits of essential oils, they are considered very safe, especially when applied topically (to the skin). The main side effects reported include skin irritation, allergic skin reactions and a type of irritation called phototoxicity. Phototoxicity has been reported when skin is exposed to sun after application of certain essential oils. Safety testing on essential oils shows minimal adverse effects and some of these products are classified as GRAS (generally recognized as safe) by the U.S. Food and Drug Administration.

However, ingestion of large amounts of essential oils is not recommended, because these uses are not well tested. According to the NCI report on essential oils, women with breast cancer should avoid lavender and tea tree oil. One study found that repeated application of these oils was associated with reversible prepubertal gynecomastia in adolescent boys. Gynecomastia refers to enlargement of a boy’s or man's breasts, usually due to a hormone imbalance or hormone therapy. Prepubertal refers to the fact that the boys had not yet gone through puberty. Reversible means that in each boy, shortly after the use of these two essential oils was discontinued, the breast enlargement resolved (went away on its own).

The study authors felt that the gynecomastia occurred because of the possible weak estrogenic and antiandrogenic (anti-male sex hormone) activities of lavender and tea tree oils. Avoiding these two essential oils is recommended in patients with estrogen-dependent tumors.

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About LBBC

Suzanne Dixon, MPH, MS, RD

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  • Registered dietitian and epidemiologist
  • Creator of an award-winning cancer nutrition website
  • Appointed member to the National Comprehensive Cancer Network (NCCN)

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Living Beyond Breast Cancer is a national nonprofit organization that seeks to create a world that understands there is more than one way to have breast cancer. To fulfill its mission of providing trusted information and a community of support to those impacted by the disease, Living Beyond Breast Cancer offers on-demand emotional, practical, and evidence-based content. For over 30 years, the organization has remained committed to creating a culture of acceptance — where sharing the diversity of the lived experience of breast cancer fosters self-advocacy and hope. For more information, learn more about our programs and services.