Soy and Breast Cancer

Written by Dr. Steve Chaney on . Posted in current health articles, Food and Health, Nutritiion

soy and breast cancerThe Soy Controversy

Author: Dr. Stephen Chaney

 

 

Soy and breast cancer: the wars are heating up again. You may have seen the recent headlines saying: “Soy protein found to speed the growth of breast cancer!” “Eating soy may turn on genes linked to [breast] cancer growth!” “Women with breast cancer should avoid high soy diets!” It all sounds pretty scary.

If this is true, it is big news. In recent years the consensus in the scientific community has been that soy is not harmful for women with breast cancer, and that it might even be beneficial. However, some skeptics have never accepted that consensus view. Those skeptics are once again claiming that soy protein may be risky for women with breast cancer.

Let’s look at the study behind the recent headlines and see if it is compelling enough to challenge the prevailing consensus on the safety of soy for women with breast cancer.

Does Soy Protein Turn On Breast Cancer Growth Genes?

This study (Shike et al, Journal of the National Cancer Institute, Sep 4 2014, doi: 10.1093/jnci/dju 189) looked at 140 women (average age 56) with invasive breast cancer. They were randomly divided into two groups of 70 and either given soy protein or a placebo between the initial biopsy and the time that surgery was performed to remove the tumor (a period of 7 to 30 days). A second biopsy was obtained at the time of surgery.

The activity of a number of genes associated with breast cancer survival was measured in the two biopsy samples. The observation that made the headlines was:

  • For some of the women in the study the activity of several genes associated with breast cancer growth and survival was increased in the group consuming soy protein compared to the placebo group. The authors concluded: “These data raise concern that soy may exert a stimulatory effect on breast cancer in a subset of women.”

What Are The Limitations Of The Study?

The authors acknowledged the many limitations of the study, but the press has largely ignored them.

  • The increased activity of the cancer growth genes was only seen in 20% of the women studied. For 80% of the women studied soy protein consumption had no effect on the activity of genes associated with breast cancer growth and survival.
  • This effect was only seen for some of the genes associated with breast cancer growth and survival. Other breast cancer growth genes were not affected in any of the women enrolled in the study. The authors conceded that it was unknown whether these limited genetic changes would have any effect on tumor growth and survival.
  • There was no effect of soy consumption on actual tumor growth in any of the women studied.
  • This was a very short term study so it is not known whether these changes in gene expression would have continued if soy supplementation were continued for a longer period of time. There are numerous examples in the literature of initial changes in gene expression in response to a radical change in diet that disappear once the body becomes accustomed to the new diet.
  • There is absolutely no way of knowing if the observed changes in gene expression would actually affect clinical outcomes such as survival, response to chemotherapy or tumor recurrence.

Should Women With Breast Cancer Avoid Soy?breast cancer prevention

Even with all of the limitations listed above, if this were the only study to test the soy-breast cancer hypothesis, I and most other experts would probably be warning women with breast cancer to be very cautious about consuming soy.

However, as I discussed in a previous “Health Tips From the Professor” (https://healthtipsfromtheprofessor.com/soy-and-breast-cancer-recurrence/) at least five clinical studies have been published on the effects of soy consumption on the recurrence of breast cancer in women who are breast cancer survivors, both in Chinese and American populations. The studies have shown either no effect of soy on breast cancer recurrence or a protective effect. None of them have shown any detrimental effects of soy consumption by breast cancer survivors.

A meta-analysis of all 5 studies was published last year (Chi et al, Asian Pac J Cancer Prev., 14: 2407-2412, 2013). This study combined the data from 11,206 breast cancer survivors in the US and China. Those with the highest soy consumption had a 23% decrease in recurrence and a 15% decrease in mortality from breast cancer.

Another meta-analysis of 18 clinical studies found that soy slightly decreases the risk of developing breast cancer in the first place (J Natl Cancer Inst, 98: 459-471, 2006). To date there is absolutely no clinical evidence that soy increases the risk of breast cancer.

The Bottom Line

What does this mean for you if you are a woman with breast cancer, a breast cancer survivor or someone who is concerned about your risk of developing breast cancer?

  1. The study that has generated the recent headlines has so many limitations that I would not recommend any changes in soy consumption at present. It raises an interesting hypothesis that requires further study and validation. If this hypothesis holds up it may result in changes in dietary recommendations for a very small subset of women with invasive breast cancer.
  1. There are many reasons to include soy protein foods as part of a healthy diet. Soy foods are one of the highest quality vegetable protein sources and provide a great alternative to many of the high fat, high cholesterol animal proteins in the American diet.
  1. I personally feel that these studies are clear cut enough that women who are concerned about their breast cancer risk, women with breast cancer, and breast cancer survivors no longer need to fear soy protein as part of a healthy diet.
  1. The responsible websites agree with this assessment. For example, WebMD and the American Institute for Cancer Research (AICR) both say that breast cancer survivors need no longer worry about eating moderate amounts of soy foods.
  1. The irresponsible websites (I won’t name names, but you know who they are) are still warning breast cancer survivors to avoid soy completely. They are citing the latest study, with all of its limitations, as proof that they were right all along. As a scientist I really have a problem with people who are unwilling to change their opinions in the face of overwhelming scientific evidence to the contrary.
  1. Finally, I want to emphasize that the published studies merely show that soy does not increase the risk of breast cancer and is safe to use for breast cancer survivors. None of those studies suggest that soy is an effective treatment for breast cancer. The protective effects of soy are modest at best. If you have breast cancer, consult with your physician about the best treatment options for you.

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

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Should You Avoid Sugar Completely?

Posted October 24, 2017 by Dr. Steve Chaney

Is It The Sugar, Or Is It The Food?

Author: Dr. Stephen Chaney

 

Should we avoid sugar completely?  Almost every expert agrees that Americans should cut down on the amount of sugar we are consuming. However, for some people this has become a “sugar phobia”. They have sworn that “sugar shall never touch their lips”. Not only do they avoid sugar sweetened sodas and junk food, but they also have become avid label readers. They scour the label of every food they see and reject foods they find any form of sugar listed as an ingredient. Is this degree of sugar avoidance justified?

 

Should We Avoid Sugar to Keep it From Killing Us?

 

Let me add some perspective:

  • If you just take studies about the dangers of sugar at face value, sugar does, indeed, look dangerous. Excess sugar consumption is associated with increased risk of obesity, diabetes, and heart disease. However, when you look a little closer, you find that most of these studies have been done by looking at the correlation of each of these conditions with sugar sweetened beverage consumption (sodas and fruit juices).

A few studies have looked at the correlation of obesity and disease with total “added sugar” consumption. However, 71.6% of added sugar in the American diet comes from sugar sweetened beverages and junk food. None of the studies have looked at the sugar from healthy foods like fruits, vegetables, and whole grains. That’s because there is ample evidence that these foods decrease the risk of obesity, diabetes, and heart disease.

  • For example, if apples had a nutrition label, it would list 16 grams of sugar in a medium 80 calorie apple, which corresponds to about 80% of the calories in that apple. The sugar in an apple is about the same proportion of fructose and glucose found in high fructose corn syrup. Apples are not unique. The nutrition label would read about the same on most other fruits. Does that mean you should avoid sugar from all fruits? I think not.

Avoid Sugar or Avoid Certain Foods

 

avoid sugar from junk foodsThe obvious question is: “Why are the same sugars, in about the same amounts, unhealthy in sodas and healthy in fruits?” Let’s go back to those studies I just mentioned—the ones that are often used to vilify sugars. They are all association studies, the association of sugar intake with obesity and various diseases.

The weakness of association studies is the association could be with something else that is tightly correlated with the variable (sugar intake) that you are measuring. Could it be the food that is the problem, not the sugar?

If we look at healthy foods (fruits, vegetables, whole grains) they are chock full of vitamins, minerals, phytonutrients, fiber, and (sometimes) protein. Fiber and protein slow the absorption of sugar into the bloodstream. As a result, blood sugar levels rise slowly and are sustained at relatively low levels for a substantial period of time.

In sodas there is nothing to slow the absorption of blood sugar. You get rapid rise in blood sugar followed by an equally rapid fall. The same is true of junk foods consisting primarily of sugar, refined flour and/or fat.  Avoid sugar from those types of foods.

Another consideration is something called caloric density. Here is a simple analogy. I used to explain the concept of caloric density to medical students in my teaching days. There are about the same number of calories in a 2-ounce candy bar and a pound of apples (around 278 in the 2-ounce candy bar and 237 in a pound of apples). You can eat a 2-ounce candy bar and still be hungry. If you eat a pound of apples you are done for a while. In this example, the 2-ounce candy bar had a high caloric density (a lot of calories in a small package). Perhaps a more familiar terminology would be the candy bar was just empty calories.

Are Sodas and Junk Foods Killing Us?

avoid sugar from candyPutting all that together, you can start to understand why the foods the sugars are in are more important than the sugars themselves. When you consume sugars in the form of sugar sweetened beverages or sugary junk foods, your appetite increases. We don’t know for sure whether it is the intense sweetness of those foods, the rapid increase and fall in blood sugar, or the high caloric density (lots of calories ina small package) that makes us hungrier. It doesn’t matter. We crave more food, and it isn’t usually fruits, vegetables, and complex carbohydrates we crave. It’s more junk. That sets in motion a predictable sequence of events.

  • We overeat. Those excess calories are stored as fat and we become obese. [Note: The low carb enthusiasts will tell you our fat stores come from carbohydrates alone. That is incorrect. All excess calories, whether from protein, fat, or carbohydrate, are stored as fat.]
  • It’s not just the fat you can see (belly fat) that is the problem. Some of that fat builds up in our liver and muscles. This sets up an unfortunate sequence of metabolic events.
  • The fat stores release inflammatory cytokines into our bloodstream. That causes inflammation. Inflammation increases the risk of many diseases including heart disease and cancer.
  • The fat stores also cause our cells to become resistant to insulin. That reduces the ability of our cells to take up glucose, which leads to hyperglycemia and type 2 diabetes. [Note: The low carb enthusiasts will tell you carbohydrates cause type 2 diabetes. That is also incorrect. It is our fat stores that cause insulin resistance and type 2 diabetes. Our fat stores come from all excess calories, not just excess calories from carbohydrates.]
  • Insulin resistance also causes the liver to overproduce cholesterol and triglycerides and pump them into the bloodstream. That increases the risk of heart disease.
  • Sugar sweetened beverages and sugary junk foods also displace healthier foods from our diet. That leads to potential nutrient shortfalls that can increase our risk of many diseases.

However, none of this has to happen. The one thing that every successful diet has in common is the elimination of sodas, junk foods, fast foods and convenience foods. You should avoid sugar from those foods as much as possible. Once you eliminate those from your diet,you significantly enhance your chances of being at a healthy weight and being healthy long term.

 

What About Protein Supplements And Similar Foods?

Of course, the dilemma is what you, as an intrepid label reader, should do about protein supplements, meal replacement bars, or snack bars. They are supposed to be healthy, but the label lists one or more sugars. Even worse, the sugar content is higher than your favorite health guru recommends.  So, should you avoid sugar from supplements and the like?

In this case, a more useful concept is glycemic index, which is a measure of the effect of the food on your blood sugar levels. Healthy foods like apples may have a high sugar content, but they havea low glycemic index.

avoid sugar and consume protein to slow absorbptionThe same is true for the protein supplements and bars you are considering. Rather than looking at the sugar content, you should be looking for the term “low glycemic” on the label. That means there is enough fiber and protein in the food to slow the absorption of sugar into the bloodstream and stabilize your blood sugar levels.

What Does This Mean For You?

Don’t misunderstand me. I am not advocating for unlimited consumption of sugar. We should work on ways to avoid sugar or reduce the amount of sugar in our diet. On the other hand, we don’t need to become so strict that we and our family need to eat foods that taste like cardboard. We also don’t want to replace natural sugars with artificial sweeteners. I have warned about the dangers of artificial sweeteners previously.

We can go a long way towards reducing sugar by just eliminating sodas, other sugar sweetened beverages, junk foods, fast foods, convenience foods, and pastries from our diet. When considering fast foods and convenience foods, we should check the label for hidden sugar. For example, some Starbucks drinks are mostly sugar. When considering foods that are supposed to be healthy, we should look for the term “low glycemic” on the label.

So we don’t have to avoid sugar completely, but we should reduce sugar from sugar sweetened beverages and junk food.

 

The Bottom Line

 

We need to keep warnings about the dangers of sugar in perspective:

  • The studies showing that sugar consumption leads to obesity, diabetes, and heart disease have all been done with sodas and junk foods.
  • Many fruits have just as much sugar as a soda. They also contain about the same proportion of fructose and glucose as high fructose corn syrup. Yet we know fruits are good for us.
  • Diets rich in fruits, vegetables and whole grains decrease our risk of obesity, diabetes, and heart disease.
  • That is because the sugar in whole foods is generally present along with fiber and protein, which slows the absorption of sugar and prevents the blood sugar spikes we get with sodas and junk foods.
  • In the case of prepared foods like protein supplements, you should look for “low glycemic” on the label rather than sugar content. Low glycemic means that there is enough fiber and protein in the product to slow the absorption of sugar and prevent blood sugar spikes.
  • Don’t misunderstand me. I am not advocating for unlimited consumption of sugar. We should all work on ways to avoid sugar from junk foods or to reduce the amount of sugar in our diet. On the other hand, we don’t need to become so strict that we and our family need to eat foods that taste like cardboard. We also don’t want to replace natural sugars with artificial sweeteners.
  • We can go a long way towards reducing sugar by just eliminating sodas, other sugar sweetened beverages, junk foods, fast foods, convenience foods, and pastries from our diet. When considering fast foods and convenience foods, we should check the label for hidden sugar. When considering foods that are supposed to be healthy, we should look for the term “low glycemic” on the label.

For more details, read the article above.

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

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