Breast Health, the Diet Connection

The Diet, Insulin and the Breast Cancer Link

You watch what you eat. You take vitamins. You exercise. And you weigh the genetic factors, based on your family medical history. All with the hope of reducing your risk of developing breast cancer.

But the latest findings in medical journals point to another risk factor: elevated levels of the hormone insulin, which inevitably traces back to blood sugar problems. The good news is that you can control your insulin levels through diet and supplements.

The Insulin Connection

Researchers and physicians already understand many of the risk factors predisposing women to breast cancer: genetics, poor diet, inade­quate vitamin D, high levels of endogenous estrogen, and synthetic estrogens in hormone-replacement therapy. But recently, doctors have discovered that type 2 diabetes – characterized by elevated blood sugar and insulin levels – increases the risk of some cancers, particularly those of the breast, colon, and pancreas.

Elevated insulin levels are common in pre­diabetes, type 2 diabetes, and obesity. However, approximately one-fourth of thin, apparently healthy people also have elevated insulin levels. So for millions of women, insulin may be a hid­den risk factor for breast cancer.

There is, however, a huge window of opportunity for reducing insulin levels. That’s because type 2 diabetes doesn’t develop overnight. It is the end point after years of blood sugar problems, often in the form of undiagnosed prediabetes. If you tackle blood sugar problems early enough, you can eliminate your risk of diabetes and, very likely, lower your risk of breast cancer.

In one study, Geoffrey C. Kabat, Ph.D., of the Albert Einstein School of Medicine, New York City, tracked the health of 5,450 women who were part of much larger studies of 162,000 women, some of whom were given hormone therapy, dietary treatments, or calcium and vita­min D supplements.

After eight years of follow up, Kabat found that postmenopausal women with high insulin levels were twice as likely to develop breast cancer, compared with women who had rela­tively low insulin levels. Furthermore, women who had been taking placebos (i.e. not receiv­ing any type of treatment or supplement) were three times more likely to develop breast cancer. Kabat’s findings were consistent with animal studies, which determined that insulin promotes cell proliferation and stimulates the growth of breast tumors.

High levels of insulin-like growth factor-1 (IGF- 1) are also associated with a greater risk of breast cancer. IGF-1 is a peptide that stimulates cell growth and inhibits cell death – traits that are perfect for fueling the growth of cancers. According to an article in the Journal of the National Cancer Institute, cancer cells have a large number of IGF-1 receptors on their surface, mak­ing them highly responsive to high blood levels of insulin and IGF-1. Women with invasive breast cancer are more likely to have poorer outcomes if their cells show a lot of insulin and IGF-1 activity.

Eating Habits that Regulate Insulin

Is it possible to control insulin levels? The answer is yes, based on studies from both the worlds of medicine and nutrition. For example, people who take glargine, a common long-acting insulin drug, have an unusually high risk of breast cancer. Conversely, people who take certain drugs to lower blood sugar have a lower risk of breast cancer. But drugs are not normal constituents of human biochemistry, so it makes far more sense to focus on eating habits.

So what exactly revs up insulin levels? Under normal circumstances, insulin helps transport blood sugar into cells, where it’s either burned for energy or stored as fat. But when a person regularly consumes large amounts of sugary foods and beverages and sugar-like carbohy­drates, the pancreas secretes so much insulin that the body’s cells become resistant to the insulin. To compensate, the pancreas releases even more insulin, but because it can’t be used, both insulin and blood sugar remain at high levels in the blood.

Controlling your blood sugar and insulin means working to improve your eating habits.

Fresh Food

For most people, it’s a pain to count calories or carbohydrate grams, or to look up the glycemic index of foods. It’s actually quite easy to remember what’s healthy and what’s not, if you follow two of my tips. First, buy mostly fresh foods. Second, buy foods that look like real foods.

Fresh, wholesome real foods are usually not packaged, other than perhaps being wrapped in plastic. For example, chicken and broc­coli look like foods that you would find on a farm, but chicken nuggets and fries do not. It helps to limit your intake of most foods sold in boxes, cans, bottles, jars, tubs, and bags, though there are some exceptions. For exam­ple, olive oil and olive oil-based mayonnaise are acceptable foods.

Packaging usually indicates some degree of food processing, refining, or manipulation, and processing usually means a food’s original nutri­tional value has been compromised. You’ll do better with organic and whole foods because they generally undergo less processing. However, be aware that organic sugar is still sugar and organic cereals are still refined carbohydrates – both of which will raise your blood sugar and insulin levels.

Quality Protein

Protein helps lower and stabi­lize blood sugar for a variety of reasons. First, protein does not prompt a rise in blood sugar. Because blood sugar levels are more stable, protein reduces appetite, which makes it easier to lose weight. Second, protein stimulates the release of glucagon, a hormone that counter­acts and lowers insulin. While insulin helps convert blood sugar to fat, glucagon blocks this conversion. And while insulin promotes fat storage around the belly, glucagon helps burn that fat. Third, protein helps maintain muscle, the best tissue for burning blood sugar and fat. Preserving your muscle mass becomes especially important after age forty, when age-related muscle loss accelerates.

I recommend eating quality proteins such as fish, chicken, turkey, and eggs. Grass-fed beef and bison are also excellent choices. Although legumes are considered a source of protein, they also contain a large amount of carbohydrates.

High-Fiber Vegetables and Fruits

Like pro­tein, fiber also lowers and stabilizes blood sugar levels, but it works through a different mecha­nism. Soluble fiber increases the bulk of foods, which reduces appetite and slows the digestive process so blood sugar levels don’t spike.

Most vegetables contain large amounts of fiber. Potatoes are the notable exception because their starch is rapidly digested. I favor salad greens, kale, and cruciferous vegetables. Diversity is important, so try to explore a vari­ety of vegetables.

Fruits have been cultivated for greater sweetness, but blueberries, raspberries, and blackberries are both sweet and rich in fiber.

Healthy Carbs

Grain-based carbohydrates, such as wheat and corn, are highly addictive and encourage people to overeat. Sweet potatoes, winter squash, and legumes have greater nutri­tional value, but they too can be problematic if you have prediabetes or type 2 diabetes, are overweight, or don’t exercise. This is my guide­line: adjust your carbohydrate intake to your weight, blood sugar, and physical activity level. If you are overweight, have diabetes, and are a couch potato, strictly limit your intake of these carbohydrates. And remember that high-fiber veggies and fruits also contain carbohydrates, so it is possible to get your carbohydrate intake from these foods alone.

Physical Activity

Physical activity lowers both blood sugar and insulin levels. The greater your activity, the better, but I recommend that most people start slowly to avoid being discouraged. Make time for a daily walk, increasing your pace and distance over several weeks. You can also use hand weights and stair-climbing exercises to increase your arm and leg muscles.

It’s impossible to completely eliminate your risk of breast cancer – there are most likely risk fac­tors that have not yet been discovered. However, you can reduce your odds of developing this disease by controlling all known risk factors, including elevated insulin levels. Because insu­lin concentrations are related to eating habits, it only makes sense to adopt a diet that maintains relatively low insulin levels.

Supplements that Help Control Insulin and Blood Sugar


Silymarin, an extract of the herb milk thistle, has been shown to lower both blood sugar and insulin levels. It works by enhancing liver function; the liver works with the pancreas to regulate blood sugar and insulin. Studies have given people 200 mg of silymarin three times daily.


Chromium is needed for normal insulin function, and studies have found that tak­ing 500 mcg twice daily can lower blood sugar and insulin levels.

Alpha-lipoic acid

Alpha-lipoic acid, an antioxidant, improves insulin function, meaning that less insulin is needed to do its job. It has been used to treat diabetic nerve disease for decades in Germany.


Biotin, a B vitamin, regulates genes involved in glucose metabolism, and it appears to have insulin-like effects. People with diabetes and insulin resistance are often deficient in biotin. Biotin works espe­cially well when taken with chromium.

Vitamin D

Vitamin D has recently been shown to regulate both blood sugar and insulin levels. People who take vitamin D supple­ments, sometimes in combination with calcium, do a better job of maintaining normal blood sugar levels. Take 2,000 to 3,000 IU daily. You can add 500 mg of calcium daily.

Soluble fiber

Soluble fiber slows digestion, which helps avoid spikes in blood sugar levels. The most common types of soluble fiber supplements are glucomannan, beta-glu­can, inulin, alginate, and psyllium. Follow label directions for use, but in general start with one capsule daily for a week or two, then take two capsules daily.

Add your comments