Breast cancer and nutrition

breast cancer prevention?

When disease strikes down a famous person, interest in that disease increases at least temporarily.  In the case of breast cancer, already on the minds of millions of women, Elizabeth Edwards’ death will heighten interest in possible diet or nutrition interventions that prevent or cure this dreaded disease.  The most important message so far: no one food or nutrient is known to be the cause or cure.  There are numerous other physiological, lifestyle, genetic and environmental factors.  Nutrition is one piece of the puzzle.

Not that researchers haven’t been trying to find some nutrition connection for years.  Any food, nutrient or food component with a Health Halo was presumed to cure or prevent breast cancer, and researchers were on a mission to prove their assumptions right, with little success so far.  Popular research topics include:

Fruits and vegetables:  A recent study of over 400,000 people did not find any significant reduction in cancer with higher intake over 9 years.  One problem with this kind of study is the definition of “fruit and vegetables”.  One person may only eat bananas and peas, while another eats dozens of different choices, resulting in extremely different nutrient, fiber and anti-oxidant intakes, some of which could impact cancer risk.   A separate study looked at breast cancer recurrence, and found that high intake of fruits and vegetables reduced the risk, but only for patients who didn’t have hot flashes.  And another study found that high intake was associated with lower risk for cancer in post-menopausal women, but not pre-menopausal women.  A study of sulforaphane, a chemical found in broccoli, found that it inhibited breast cancer stem cell growth in mice.  While this study says nothing about humans, it does point out potential problems with surveys that lump all fruits and vegetables together.  It likely that specific fruits or vegetables have some benefit, while others do not.

Soy was initially presumed to cure or prevent breast cancer, based on the fact that Japanese women eat more soy and have lower cancer rates.   They also eat lots more rice and fish, along with other diet and lifestyle differences, compared to Western cultures.  But soy had a health halo.  Then, as breast cancer treatment became more sophisticated, scientists realized that there were different kinds of tumor cells, and that estrogens in soy could stimulate estrogen-receptor positive tumor growth, leading to recommendations to avoid soy.  The controversy continues, but current thinking is that soy isn’t likely to be harmful at normal dietary intake levels, but it also isn’t likely to have any significant beneficial effect on breast cancer risk.

Red Meat, especially processed meat products like hot dogs, sausages and bacon, is linked to increased risk for breast cancer.  One or more servings/day seems to cause the most significant increase.  Whether the risk is due to the actual meat, or to a general type of diet that’s high in red meat products, is not known.

Fiber. The term is about as nutritionally meaningful as “fruits and vegetables”, since there are many different types of fiber in foods.  Nevertheless, a recent study assessed fiber intake and breast cancer incidence.  Women in the highest 20% of fiber eaters had the lowest risk on average.  The effect was most pronounced for estrogen receptor negative tumors.  It was also more significant for soluble fiber (oats, apples) than insoluble (vegetables, fruit, other whole grains, beans).

Fat: while there is some increased risk with increased fat intake, it’s modest.  The bigger question is whether it’s the fat, the foods that are high in fat, or the fact that those high fat foods are displacing other foods that are beneficial.  Or because high fat diets are linked to …

Obesity: of all the nutritional issues, this is the one that clearly shows a link to risk for breast cancer, increased likelihood of recurrence and more aggressive tumor recurrence.  Yet it receives the least attention in the media, from doctors or from support groups.  This is extremely unfortunate, because weight loss and a healthy lifestyle are positive steps every woman can take, on her own.

Vitamins: Attempts to identify a magical vitamin cure for breast cancer have yet to produce results.  In fact, excess intake of some vitamins may actually enhance tumor growth, or block action of chemotherapy drugs, protecting cancer cells.  Vitamin D is now being investigated for a connection, and there is some evidence that higher intake and higher blood levels are associated with decreased risk, especially when compared to women with deficient blood levels.  Find answers to specific questions on other vitamins, herbs and antioxidants here, in a Q & A with cancer experts.

If you want to reduce your risk for breast cancer, the most effective step is to manage your weight, keeping it in normal range, eat a healthy balanced diet with plenty of dark-colored vegetables and fruits, limited red meat and lots of fiber.  In other words, a Mediterranean style diet, which, by the way, is associated with decreased risk for breast cancer.  Don’t overload on vitamin supplements of any type, and get your vitamin D checked.

If you have breast cancer, consult with a registered dietitian who specializes in cancer care.  Typically someone with that speciality works with an oncology practice, or is referred by your doctor.  Cancer nutrition is a highly specialized field, and doctors and nurses do not have the training, expertise or time to counsel on diet.  Don’t buy supplements or make diet changes based on myths or rumors you read on the internet or hear from friends, family or a vitamin store clerk.

For more information: American Cancer Society

Tags: breast cancer and nutrition, breast cancer diet, fiber, obesity, Supplements, Vitamins, women's nutrition

This entry was posted on December 9, 2010 at 10:38 am and is filed under Diets, Health Halo alert, Nutrients, obesity, Research News, Vitamins, Weight Control, Women's nutrition. You can follow any responses to this entry through the RSS 2.0 feed.