Tell me what you eat, and I will tell you what you are – Anthelme Brillat-Savarin, "The Physiology of Taste"

The next time you sit down to eat; you may look at your food differently. Freshly squeezed orange juice will be the sign, of that daily boost, to keep your vitamin C deficiency at bay. You may want to avoid the cheese bagel so your salt gene will not stress you out. Or that moist brownie will be the sign of your sugar genes going into overdrive!

Mildly put, your genes, not your nose or eyes, influence your taste though not always to the advantage of your health. That’s what nutrigenomics, the study of the response of genes to dietary nutrients, is all about.

Research in nutrigenomics is now being used to identify the risk of developing chronic diseases like diabetes, cardiovascular disease and cancer. Dietary supplements are increasingly playing a role in cancer care. It is useful to have our daily dose of vitamin D, or that pinch of curcumin in lentil soup, or that refreshing cup of green tea. They could well be our essential, preventive, dietary agents from that deadly disease, cancer. Unregulated growth of cells in the body results in cancer.

This unregulated growth is due to several factors: errors in the genetic material (DNA), errors in proteins that form the basis of different regulatory pathways within the body, and/or environmental effects (smoking, air pollution, contamination of water, etc) on cells. Dietary supplements and nutrients are proving to be multi-faceted agentsin preventing, and treating cancer. This article will be an assessment of the current status of nutrition research in the field of cancer.

Dietary supplements in cancer care

The Clinical Practice Committee of the Society of Integrative Oncology (SIO), recently published a paper on effective dietary supplements that can be used in cancer care. The paper was interesting because the target audience were clinicians, rather than patients.

Physicians are reluctant to acknowledge the benefits of natural treatments due to insufficient knowledge. Hence, the necessity for a comprehensive overview of natural supplements. A study by the University of Alberta showed that 40% Canadians use vitamins and mineral supplements. Of those who took supplements, a majority of them were women, older people, and those with a predominantly fruit and vegetable diet.

The SIO review discusses the insufficient trust between physicians and their patients in cancer care. Many patients try to avoid the debilitating effects of chemical radiation and other pharmaceutical therapies, on the body, by switching to less invasive, wholesome, natural remedies. Such patients are reluctant to inform their physicians about alternative therapies since physicians do not perceive such treatments to be useful. In most cases, it has been observed, the physician is not clear about the natural remedy being followed.

Physicians, trust tried and tested drug therapies that are widely practiced. The overview of dietary supplements is a useful tool for doctors and other physicians involved in treating cancer.

The ten dietary supplements that have been recommended include, curcumin, glutamine, vitamin D, fish oil, milk thistle, green tea, probiotics, melatonin, astragalus membranaceus, and maitake mushrooms. Each of them, have shown effective anti-cancerous properties either in patients or in laboratory studies. Curcumin, green tea, fish oil, and vitamin D are found to be effective in retarding cancer growth. Glutamine, milk thistle, melatonin, astragalus, maitake mushrooms, and probiotics are effective in retarding the debilitating effects of conventional chemotherapy.

The Ottawa Integrative Cancer Centre (OICC) is a naturopathic regional centre of the Canadian College of Naturopathic Medicine. Dr. Laura Weeks, a research associate, confirms the use of the above dietary supplements in the treatment of cancer patients. She however states that, “I can say that physicians (ie, medical doctors) in Canada do not recommend any of the dietary supplements described in the SIO authored article.” A viewpoint corroborated in an article, by Mark Weir and others, in the British Journal of Nutrition.

We use many of the mentioned supplements in our diet. We eat mushrooms in salads, have yogurt enriched with probiotics, and sip a refreshing cup of green tea. Concentrated forms of these supplements are used in research, which means, a higher recommended dose than we normally consume in our regular diet.

Treatment regimens require high doses in order to have a substantial effect. It would be even better if we are advised an appropriate diet, to prevent the onset of cancer, based purely on our genomic profile. This is where the science of nutrigenomics may provide the answers.

Gene-diet relationship

Nutrigenomics, as mentioned earlier, utilizes the information from our body’s genome, (gene map) to ascertain the amount of nutrients our body needs. This provides the individual an understanding of the types of nutrients that may not agree with his/her genetic system. Dr. Ahmed El-Sohemy, in his article in the journal Personalized Medicine, articulates this point in simple terms by stating the case of lactose intolerance in certain people.

Certain individuals are unable to metabolize the milk protein, making them avoid lactose-based products and shifting to an alternate (lactose-free milk/soy milk/vitamin-D enriched orange juice) diet. When informed of the genetic variation in the lactase enzyme, necessary for metabolizing milk products, such individuals definitely avoid the discomfort resulting from milk product consumption.

Lactose intolerance is one of the many examples of nutrient metabolism gone awry. The information from nutrigenomics would also certainly aid in tackling and avoiding the risk of developing chronic diseases, such as cardiovascular disease and cancer.

That said, there are commercially available tests that provide genetic profile information to the consumer. A recent commercially available test was developed and marketed by the company, Nutrigenomix, Inc., in Canada under the same name. This University of Toronto startup, founded by Dr. Ahmed El-Sohemy, launched the Nutrigenomix kit in 2012. Since then, the product has been launched in Australia, United States, and Chile. The kit costs ~$350 and involves a simple saliva sample in order to test 7 relevant diet-related genes. Once the test results are obtained, a trained dietitian (who is registered with a provincial regulatory body) can provide appropriate advice on the prescribed diet for the individual.

Dr. Ahmed states that the response by the public, to these kits, has been positive. A paper by Dr. Ahmed, discusses the altered perceptions of consumers and enhanced motivation to change their dietary regimen based on the test results. Currently there are over 80 clinics across Canada, with trained dietitians, that offer the Nutrigenomix tests.

The debate

The information from commercially available tests is indeed empowering to the individual, however, the average Canadian needs to be better informed of the relevance of these tests. Mark Weir and others, in their survey, state that healthcare professionals (physicians, dietitians) would feel more confident of recommending such test kits if they are validated by Health Canada.

Currently, most commercially available test kits are available to the public irrespectiveof the recommendations of healthcare professionals. This poses concerns since the test kits may or may not provide comprehensive information, which will enable patients to make their own health and diet choices. It may also result in the use of some ineffective treatment strategies by the patient without a physician’s consent.

Dr. Ahmed states however, that there is a fundamental difference between the Nutrigenomix test kit and other commercially available test kits. The Nutrigenomix test kit is sold only through a trained dietitian-a healthcare professional under the title Registered Dietitian/Professional Dietitian/Dietitian- qualified to conduct these tests. Hospitals expressed a great deal of interest, in the Nutrigenomix kit, at a recent talk by Dr. Ahmed for Nutrition Awareness Month in March 2013 in Toronto.

While provincial healthcare plans currently do not cover these tests, some private healthcare plans cover a dietitian’s costs and some may even cover the costs of the test. With wider acceptance by healthcare professionals, nutrigenomics testing can provide patients with options for prevention that are tailored to their individual genetic profile.

The horizon of hope

The road to personalized nutrition has certainly been charted out. The prevalence of technology in every spectrum of human life is obvious and nonetheless so in the healthcare industry. Patients are feeling empowered with educational tools and internet resources. Physicians are aware of the numerous possibilities of the science of nutrigenomics, viz. personalized nutrition profiles to counter the risk of developing chronic diseases such as cancer, improving healthy lifestyles, and long-term reduction in healthcare costs.

A collaborative approach between physicians, dietitians, nutritional scientists and healthcare officials will stimulate and propel the field of nutrition and the integration of dietary supplements in cancer care. The horizon of personalized treatment is visible and with it, the possibility of a renewed lease on life.