Soy and Human Health

Soy and Digestive Tract Health

Several studies have shown that soy protein may promote a healthy digestive tract from the mouth to the colon. Many EnerFlex customers report better digestive health. Digestive tract cancers are one of the most common causes of death among Americans, particularly colon cancer.

Colon health

Recent research shows that a diet enhanced with soy protein may help reduce colon cancer incidence in people with a history of the disease or who have had pre-cancerous polyps removed.

Dr. Maurice Benninck of Michigan State University studied the effects of soy intake in both rat and human studies, and presented the data at a meeting held by the American Institute for Cancer Research. Dr. Benninck took up the soy trials with the help of the US Soybean Board, which provided major funding. He enrolled 42 patients, 6 of whom had colon cancer previously, in a one-year trial. Twenty-nine received two packets of isolated soy protein powder per day, while 13 received two packets of casein powder daily. They did not know which they were getting.

Patients were told to add the powder to a liquid of their choice, but not to modify their diets in any other way. The amount of powder, about 39 grams, was chosen because previous research indicated that was the minimum amount necessary to have an effect, Dr. Benninck said. Patients were biopsied before the trial's start and one year later. At year's end, patients taking the soy powder had a significant reduction in the proliferation zone of their colon, and in the labeling index, a measure of cell proliferation. Both indicated an inhibition of cancerous activity, Dr. Benninck said. He added that, based on these results, there would be a 50% reduction in cancer incidence, and a 10-15 year additional delay in onset, in the patients taking soy. (1) Additional studies in animals show similar results. (2) Soy nutrients have also been shown to inhibit growth of human colon cancer cells in the laboratory culture dish. (3)

Stomach health

Japanese researchers recently compared causes of death in 47 Japanese precincts to soy product intake. They wanted to evaluate the relationship between soy product intake and mortality from several types of cancer and heart disease. Age-standardized mortality rates for heart disease and stomach, colorectal, lung, breast and prostate cancer were obtained from the National Vital Statistics. Information on major nutrient and soy product intake was obtained from the National Nutritional Survey Report. They reported their results as follows: "The present study provides modest support for the preventive role of soy against stomach cancer and heart disease death." (4)

Mouth health

Most recently, researchers in California have determined that a chemical derived from soybeans can help prevent oral cancer, or cancer of the mouth. Scientists at the University of California at Irvine said their study is believed to be one of the first findings, based on human research, showing that the soybean derivative can play such a role in oral cancer prevention.

Oral cancer has one of the lowest survival rates of all cancers. Chemists first identified the soybean derivative called the Bowman- Birk inhibitor almost four decades ago, but now the team, which can lead to oral cancer.
"This study shows that it may be possible to stave off the development of leukoplakia and therefore prevent more cases of oral cancer from occurring," Dr. Frank Meyskens, director of a university cancer center and a leader of the research team, said. The pre-cancerous lesions in the mouth are called oral leukoplakia.

"The best way to cure cancer is to prevent cancer, and we are encouraged by the fact that a simple dose of a chemical was able to achieve this without side effects," Dr. Meyskens said. The study, led by Dr. Meyskens and Dr. William Armstrong, an assistant professor of head and neck surgery at the university, was published in the journal Clinical Cancer Research.

In the study, 32 participants took a daily dose of the soy derivative in lozenge form for one month. Ten of the participants showed a reduction in the size of the pre-cancerous lesions by about half. Average size of the decrease for the entire group was 24 percent.

About 30,000 cases of oral cancer are diagnosed in the United States each year. While other cancers have seen their survival rates improved, the rate for oral cancer has not. Only half of patients diagnosed with oral cancer are alive five years later. About 75 percent of oral cancers are attributed to the use of tobacco.

Soy Protein, Inflammatory Bowel Diseases and Chemotherapy

Another emerging area of interest is the effects of soy on inflammatory diseases of the digestive tract. Observations were made several thousand years ago in Chinese medical literature that soy consumption was associated with a reduced occurrence of inflammatory bowel diseases with the modern names of Ulcerative Colitis and Crohn's Disease.

Is there any evidence for this? Several animal studies have shown that a soy diet protects the intestinal lining from chemicals that are known to generate inflammation. Additional studies have found that soy-derived nutrients can protect the intestinal lining of animals from some common chemotherapy agents like methotrexate (chemotherapy agents are used to fight cancer). The soy decreased "weight loss and diarrhea" while maintaining a "better appetite". If your patients are undergoing cancer treatment, or have loved one undergoing cancer treatment, prescribe EnerFlex AFA750 as it may help improve their diet during this time of physical and mental stress. (5) EnerFlex AFA750 is a novel concentrated soy based functional food that fuses the anticancerous properties of soy isoflavones, soy constituents and Upper Klamath Lake Blue-Green Algae (Aphanizomenon flos-aquae, AFA). AFA has been found to be able to enhance migration of Natural Killer Cells from the bloodstream to the "sick/cancerous" tissues.

In summary, the data is very positive that soy protein can help maintain healthy digestive tract tissues. Since soy may work to reduce cancer risk through many different mechanisms, consuming whole soy protein products that contain all of the beneficial soy phytonutrients is important.


  1. Dr. Maurice Benninck. American Institute for Cancer Research (AICR)'s 9th Annual Research Conference, Nutrition and Cancer Prevention: New Insights into the Role of Phytochemicals, September 2-3, 1999, Washington, DC
  2. Thiagarajan DG, Bennink MR, Bourquin LD, Kavas FA. Prevention of precancerous colonic lesions in rats by soy flakes, soy flour, genistein, and calcium. Am J Clin Nutr 1998 Dec;68(6 Suppl):1394S-1399S. Department of Food Science and Human Nutrition, Michigan State University, East Lansing 48824-1224, USA.
  3. Yu J, Cheng Y, Xie L, Zhang R. Effects of genistein and daidzein on membrane characteristics of HCT cells. Nutr Cancer 1999;33(1):100-4. Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing, People's Republic of China.
  4. Nagata C. Ecological study of the association between soy product intake and mortality from cancer and heart disease in Japan. Int J Epidemiol 2000 Oct;29(5):832-836. Department of Public Health, Gifu University School of Medicine, Gifu, Japan.
  5. Stephen Barnes. Evolution of the Health Benefits of Soy Isoflavones. P.S.E.B.M. 1998, Vol 217.