BRCA Breast Cancer Genes & Soy Consumption Research Results

Why do people who eat legumes—beans, chickpeas, split peas, and lentils—live longer? Well, men and women who eat legumes tended towards being lighter, having a slimmer waist, lower blood sugars, lower cholesterol, lower triglycerides, better kidney function, lower blood pressure, and so—no surprise—may live longer. But, interestingly, bean intake was “a better protectant against mortality in women than men.” They think this may be because cancer was the leading killer of women in this population—especially breast cancer. And, we know that breast cancer survivors who eat soy foods, for example, have a significantly lower likelihood of the cancer recurrence. Eating soy foods appears to protect against the cancer coming back. This 2012 review looked at three prospective human studies done to date, and found that women who ate the most soy had a 29% lower risk of dying from breast cancer, and a 36% lower risk of cancer recurrence. And, a fourth study was since published, and it showed the same thing. “[S]oy food intake is associated with longer survival and lower recurrence among breast cancer patients. With an average intake of soy phytonutrients above 17 milligrams a day, which is about what’s found in a single cup of soy milk, the mortality of breast cancer may be able to be reduced by as much as 38%.

Here’s the survival curve over five years. The purple line represents the survival of the women with the highest soy consumption. As you can see, after two years, all the breast cancer survivors eating lots of soy were still alive. But, a quarter to a third of the women who ate the least soy were dead. And, after five years, 90% of the tofu-lovers were still alive and kicking, whereas half of the tofu-haters kicked the bucket. And, you can see a similar relationship when you look at breast cancer survival and soy protein intake, as opposed to soy phytonutrient intake.

How does soy so dramatically decrease cancer risk, and improve survival? Soy may actually help turn back on BRCA genes. BRCA is a so-called caretaker gene, an oncosuppressor—meaning a cancer-suppressing gene responsible for DNA repair. Mutations in this gene can cause a rare form of hereditary breast cancer, popularized by Angelina Jolie’s public decision to undergo a preventive double mastectomy.

But, only about 5% of breast cancers run in families. So, 95% of breast cancer victims have fully functional BRCA genes. So, if their DNA-repair mechanisms are intact, how did breast cancer form, grow, and spread? Well, tumors do it by suppressing the expression of the gene, through a process called methylation. The gene’s fine, but cancer found a way to turn it off, or at least turn it down—potentially facilitating the metastatic spread of the tumor.

And, that’s where soy may come in. Maybe the reason soy intake is associated with increased survival and decreased cancer recurrence is because the phytonutrients in soy turn back on your BRCA protection—removing the methyl straightjacket the tumor tried to place on it.

So, researchers put it to the test. These are three different types of human breast cancer, specially stained so that the expression of BRCA genes turns up brown. So, this is what full DNA repair would look like—hopefully, what normal breast cells would look like. Lots of brown, lots of BRCA expression. But, instead, we have column two, raging breast cancer.

Well, if you add soy phytonutrients back to the cancer, BRCA does indeed get turned back on. The DNA repair appears to start ramping back up—though this was at a pretty hefty dose, equivalent to about a cup of soybeans.

Their results suggest that treatment with soy phytonutrients “might reverse DNA hypermethylation, and restore the expression” of the tumor-suppressor genes BRCA1 and BRCA2. May help with other breast cancer genes, as well. “Women at increased [genetic] risk of breast cancer may especially benefit from high [soy] intake.”

Doctor’s Notes

Legumes leading to a longer life? See Increased Lifespan from Beans.

No matter what genes we inherit, changes in diet can affect DNA expression at a genetic level. For example, see:

I’ve previously covered the available science in Breast Cancer Survival & Soy. Other effects are detailed in:

It may be possible to overdo beans, though (see How Much Soy Is Too Much?).

For further context, check out my associated blog posts: Top 10 Most Popular Videos of 2013 and Can Eating Soy Prevent Breast Cancer?

If you haven’t yet, you can subscribe to my videos for free by clicking here.

In health,
Michael Greger, M.D.

Michael Greger, M.D., is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous “meat defamation” trial. Currently Dr. Greger proudly serves as the Director of Public Health and Animal Agriculture at the Humane Society of the United

Citrus Peels and Cancer: Zest for Life?

Breast Cancer Prevention With CitrusNew data demonstrating a DNA protective agent was present in at least some fruits and vegetables found that the agent was heat sensitive and determined it was not vitamin C. This was confirmed in a study that tried vitamin C directly and found no effect on DNA protection and repair of DNA strand breaks.

The carotenoid beta cryptoxanthin, found primarily in citrus, seems to be at least one candidate. If you expose cells to a mutagenic chemical, you can cause physical breaks in the strands of DNA, but in less than an hour, our DNA repair enzymes can weld most of our DNA back together. But if you add some of that citrus phytonutrient, you can effectively double the speed at which the DNA is repaired. But this is all just cells in a petri dish, what about in a person?

If you have people drink a glass of orange juice and draw their blood two hours later, the DNA damage you can induce with an oxidizing chemical drops, whereas if they just had like orange Kool-Aid, it didn’t help.

So, do people who eat more fruit walk around with less DNA damage? Yes, particularly in women. Does this actually translate into lower cancer rates? Yes, citrus alone is associated with a 10% reduction in odds of breast cancer.

Given to newly diagnosed breast cancer patients, citrus phytonutrients were found to concentrate in breast tissue, though many complained of “citrus burps” due to the concentrated extract they were given; so, researchers evaluated topical application as an alternative dosing strategy, recruiting women to apply orange flavored massage oil to their breasts daily. This request was met with excellent compliance, but it didn’t work. We actually have to eat our food.

Why not just take carotenoid supplements to boost our DNA repair? Because it doesn’t work. Although dietary supplements did not provoke any alteration in DNA repair, dietary supplementation with carrots did. This suggests that the whole food may be important in modulating DNA repair processes.

Though orange juice consumption was found protective against childhood leukemia, it was not found protective against skin cancer. However, the most striking feature was the protection purported by citrus peel consumption. Who eats orange peels? Lots of people evidently. Just drinking orange juice may increase the risk of the most serious type of skin cancer. Daily consumption was associated with a 60% increase in risk; so again, better to stick with the whole fruit. And you can eat citrus extra-whole by zesting some of the peel into your dishes.

Featured Photo, Recipe and Article: Activate Lemon’s Hidden Anti-Cancer and Anti-Inflammation Powers by Freezing Them Like This

Michael Greger M.D.About Michael Greger M.D.Michael Greger, M.D., is a physician, author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous “meat defamation” trial. Currently Dr. Greger proudly serves as the Director of Public Health and Animal Agriculture at the Humane Society of the United States.

Specific Receptors for Specific Fruits and Vegetables

Cancer Prevention With DiversityWhy does dietary diversity matter? Because different foods may affect different problems. Cabbage, cauliflower, broccoli, and Brussels sprouts are associated with lower risk of colon cancer in the middle and right side of our body, whereas risk of colon cancer further down on the left side of our body appears to be lowered by carrots, pumpkins, and apples. So, different fruits and vegetables may confer different risks for cancer of different parts of even the same organ.

Variety is the spice of life and may prolong it. Independent of quantity, variety in fruit and vegetable consumption may decrease lung cancer risk, meaning if two people eat the same number of fruits and vegetables, the one eating a greater variety of them may be at lower risk.

And it’s not just cancer. In a study of thousands of men and women, a greater quantity of vegetables and a greater variety may independently be beneficial for reducing the risk of type II diabetes. Even after removing the effects of quantity, each different additional two items per week increase in variety of fruit and vegetable intake was associated with an 8% reduction in the incidence of diabetes. Why? Well, it may be attributable to individual or combined effects of the many different bioactive compounds contained in fruits and vegetables; thus, consuming a wide variety will increase the likelihood of consuming more of them.

All the vegetables may offer protection against chronic diseases, but each vegetable group contains a unique combination and amount of these phytonutrients, which distinguishes them from other groups and vegetables within their own group. Because each vegetable contains a unique combination, a great diversity of vegetables should be eaten to get all the health benefits.

Does it matter, though, if we get alpha-carotene or beta-carotene—isn’t an antioxidant an antioxidant? No, it’s been shown that phytochemicals bind to specific receptors and proteins in our bodies. For example, there’s a green tea receptor in our body, a receptor for EGCG, a key component of green tea. There are binding proteins for the phytonutrients in grapes, onions, and capers. I’ve talked about the broccoli receptor already. Recently, a cell surface receptor was identified for a nutrient concentrated in apple peels, and importantly these target proteins are considered indispensable for these plants foods to do what they do, but they can only do it if we eat them.

Just like it’s better to eat a whole orange than just take a vitamin C pill, because otherwise, we’d miss out on all the other wonderful things in oranges that aren’t in the pill, by also eating a different fruit, like an apple, we won’t miss out on all the wonderful things in apples that aren’t in the orange. When it comes to the unique phytonutrient profile of each fruit and vegetable, it’s like comparing apples to oranges.

Doctor’s Note

This is one of the reasons I developed my Daily Dozen Checklist of foods to incorporate into one’s routine. You can download the iPhone and Android apps (for free!).

I’ve previously covered how produce variety—not just quality and quantity—may be important in Apples and Oranges: Dietary Diversity and Garden Variety Anti-Inflammation.

Featured photo source: Isagenix

Michael Greger M.D.About Michael Greger M.D.Michael Greger, M.D., is a physician, author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous “meat defamation” trial. Currently Dr. Greger proudly serves as the Director of Public Health and Animal Agriculture at the Humane Society of the United States.

%d bloggers like this: