Carbohydrate, Insulin & Cancer

If you are like me, you adopted a low carbohydrate lifestyle primarily to lower the size of your jeans. A great benefit, no doubt, but according to some new research it turns out that we may be protecting ourselves from cancer as well. For many years, scientists have theorized why the cancer rates in the United States continue to rise despite the dramatic improvements in health care. You know the popular theories. Maybe it is the increased use of pesticides and herbicides by farmers. Maybe it is the increased use of preservatives in our food. Maybe it is the pollution in our air. More and more it is beginning to look as though a big part of the cancer puzzle may be our growing appetite for carbohydrate-laden foods.

The "Carbohydrate and Cancer" theory got a big boost in April when a team of Swedish researchers announced that using high heat to cook carbohydrate-dense foods creates alarming amounts of a cancer-causing agent known as acrylamide. Then in May, the Great Britain Food Standards Agency (FSA) confirmed these findings in their own study.

This story started when scientists at the University of Stockholm in Sweden found that high levels of acrylamide are formed when high carbohydrate foods are fried or baked. Since these foods include some of the most popular foods in the world (French fries, potato chips, bread, etc.) this announcement sent shockwaves through the nutrition community and received widespread attention from the media. For example, I heard about it from Tom Brokaw in the first 15 minutes of the evening news -- a time reserved for the hottest news of the day. This study was not published in medical journals because the researchers were so concerned about their findings that they felt obligated to release the results immediately to the public and publish them in professional journals later. In an official press release issued by the Swedish National Food Administration they state, "....it seems reasonable to conclude that a significant number, perhaps several hundred, of the annual cancer cases in Sweden can be attributed to acrylamide."

In a response to the frenzy generated by the Swedish study, the Great Britain Food Standards Agency (FSA) performed their own study to either confirm or dispute the Swedish findings. The FSA reported that they also found high levels of acrylamide in fried and baked foods. In the official press release, they state, "....since acrylamide is classified as a genotoxic carcinogen, the Agency's view is that it should not be present in foods or, if it cannot be removed, that is should only be present in the lowest possible levels." However, they soften their statement later when they also say, "We are not recommending that people change either their diet or cooking methods as a result of these studies."

The United States Food and Drug Administration (FDA) has not released a statement about acrylamide in high carbohydrate foods, but there seems to be little doubt that these studies are of serious concern. International scientist are so troubled by these studies that the World Health Organization (WHO) plans to review them and make recommendations in their meeting in June. Hopefully, they will release a statement immediately after the meeting. I will watch for it and keep you updated!

While the acrylamide studies have grabbed media headlines, the connection between high carbohydrate intake and cancer certainly is not new. In the past several years, there has been a quiet stream of research studies that have looked at this connection from a different perspective. The question they have been striving to answer is this: Does insulin prompt cancer cells to grow? So far, it is looking as though the answer is yes. More and more researchers are concluding that insulin causes several cancers to grow including colon and breast cancers. Here are a few studies that have particularly grabbed my interest.

I chose to include this first study because a researcher from Harvard University in Boston, Dr. Edward Giovannuci, reviewed over 250 research studies regarding the affects of high carbohydrate diets, high insulin levels and colon cancer. He concluded that there is strong evidence that high carbohydrate diets lead to colon cancer. He specifically states that colon cancer was infrequent before technology increased the availability of highly processed carbohydrate. He further states that lowering carbohydrate intake has "?the most potential to reduce colon cancer incidence, as well as cardiovascular disease and diabetes mellitus." Dr. Giovannuci's article is titled Insulin, Insulin-Like Growth Factors and Colon Cancer: A review of the Evidence, and it was published in the Journal of Nutrition in 2001.

This next topic is near and dear to all of our hearts -- breast cancer. Harvard University researchers have also been hard at work looking at the connection between insulin and breast cancer growth and development. In a huge study in 1998, they reviewed breast cancer cases from the famous Nurses Health Study group going back to 1976. They found a strong correlation between insulin levels and breast cancer development in premenopausal women (but not postmenopausal women). In fact, they estimate that premenopausal women with high insulin levels have a sevenfold increase in the risk for developing breast cancer (wow!). This study was published in the medical journal The Lancet in 1998.

In another breast cancer study in 2000, researchers at the University of Toronto in Canada found that women with breast cancer who have high insulin levels were more likely to progress to more advanced stages and more likely to die from the disease. They concluded that a woman's insulin level could be used to predict her odds of surviving the breast cancer even when aggressive medical therapy is given. This article, Fasting Insulin Predicts Distant Disease Free Survival and Overall Survival in Women with Operable Breast Cancer Who Are Receiving Standard Adjuvant Therapy, was published in the American Society of Clinical Oncology Journal of Clinical Oncology.

The news about these and other compelling research studies is slowly making its way into the mainstream medical communities. For example, the National Brain Tumor Foundation in Oakland, California is so convinced by the studies linking carbohydrate and insulin to cancer growth they recently revised their dietary guidelines in a dramatic way. In the group's published dietary guideline entitled The Healing Power of Your Fork: A Brain Tumor Survivor's Eating Plan, they advise brain cancer patients to avoid low fat diets and to cut out sugar and refined carbohydrate instead. They warn patients that eating refined carbohydrate not only feeds cancer cells it suppresses the immune system as well. The really great news is that a dietitian wrote the guideline. Yes, you read it correctly -- a dietitian! Perhaps the low carbohydrate message is finally beginning to be accepted the nutrition community?

I chose this final study simply because I found it to be fascinating. Is does not really qualify as a scientific study since it involved only two cancer patients, but it is compelling. Researchers at the Case Western Reserve University in Cleveland, Ohio reported on two pediatric patients who had advanced stages of cancer. They decided to try to "starve" the cancer cells by restricting carbohydrate to the point of ketosis. Using PET scans, they observed that the tumors' glucose uptake (how much glucose the tumors "eat" so to speak). They found that while the children were in ketosis their tumors took up 21% less glucose than when they were not in ketosis. One of these children remained in ketosis for 12 months with no tumor progression. This fascinating article was published in The Journal of American College of Nutrition in 1995.

So there you have it. It looks as though there is a strong connection between carbohydrate, insulin and cancer growth. In the interest of brevity I included only a couple of studies for this column. If you would like to read more studies on the topic, go to my website at www.lowcarbsuccess.net and click on the RESEARCH button. If you know someone who has cancer or who is at high risk for developing it, you may want to share this information with her/him. It might just save their life!