I recently wrote an article for HealthCentral, Diet Not Working? Paying Attention to Genetics Might Help, which discussed the idea that diets need to be individualized, taking into account how much weight you personally need to lose, food preferences, work schedule, family health history, in order to create a diet that has the potential to achieve your goals. The article also discussed how there is genetic diversity among people – not everyone responds to food groups and calorie counts the same way.
The column referenced a 2011 mouse study that compared different diets. Mice lost weight at different paces based on the particular strain of mouse involved and which diet that group followed. Ketogenic diets seemed to have the best results among all groups, but still, there were differences based on mice strains. So is a “diet based on genetics” the future for achieving optimal weight loss and optimal health?
Most people can achieve weight loss by measuring portions of foods and deciding on a daily calorie count in addition to exercise efforts. Targeting optimal health as a secondary goal is usually achieved by consuming high quality choices from each of the six food groups. But there are individuals who need unique recommendations – strict limitations on carbohydrates for example, in order to achieve ongoing weight loss. That’s why it may seem intuitive to embrace the concept of dieting by genetics.
When researchers discuss the impact of dieting on genes, what they are really suggesting is the notion of either turning genes on or turning genes off (keeping them silent) to achieve a specific outcome. Genes are made up of strings of DNA, and they are literally the blueprint for synthesizing everything that makes life possible. That includes all kinds of cells, antibodies, and hormones, like insulin. What flips a gene switch into on or off position? Epigenetic marks like the methyl group (a carbon atom bonded to three hydrogen atoms). If enough methyl groups attach to a gene, they can turn the gene off or significantly limit its activity. If enough acetyl groups (two carbons, one oxygen, and three hydrogen atoms) attach to certain genes, they can turn the gene on. What’s key to this discussion is that epigenetic marks can appear and disappear based on diet, weight of the person, stress and exposure to toxins like tobacco or DDT.
A 2005 study suggested that high fat diets seem to affect expression of genes that are involved in mitochondrial function and biogenesis, fueling an increased likelihood of a person developing obesity and diabetes. In 2008, EMBO Press published the report, We Are What We Eat, based on the research that looked at the link between diet, evolution and genetic influences. In 2011, Science Daily discussed how genes respond to the foods we choose to eat, based on research done at The Norwegian University of Science and Technology.
Researchers do caution that when it comes to the impact of diet, the science of genetics and epigenetic markers has been well documented in mice and rats BUT we are still in the “may” also be true in humans stage of research. According to David Katz, M.D., founder of True Health Initiative, he explained in an email that, “Research examining the effects of customizing dietary interventions for weight loss based on genetic variation is at a fascinating, but very early stage. Most of the claims about genomic personalization are as yet well ahead of the science.
“I believe there is an opportunity in this area to take the fundamentals of healthful eating that pertain to us all, and tweak them based on inter-individual genetic variation, but we are not really there yet,” Dr. Katz said. “We are still just figuring out where there is!”
A book hitting the market in April 2017, The Genetics of Health: Understand Your Genes for Better Health by Sharad P. Paul, M.D., further extends this idea of personalizing your lifestyle choices based on your genes, and understanding the link between our evolutionary past and our future wellbeing. Dr. Paul suggests that identifying your gene blueprint and then making lifestyle choices that work specifically for your set of genes can allow you to optimize mental and physical fitness, improve wellness, and even extend life. The book explores the growing evidence that supports looking at one’s diet from a genetic perspective, and each chapter in the book offers practical tips and action plans.
Identifying personal response or lack of optimal response to drugs or drug combinations is being used in cancer therapies, where precious time cannot afford to be lost on treatments that will not work, based on an individual’s response.
Clearly when it comes to diseases like obesity, diabetes, heart disease and cancers, using genetic testing to determine lifestyle habit choices can be a huge game changer. According to Andrea Giancoli, M.P.H., R.D., she explained to me, "Nutrigenomics, the impact of food on gene expression and how that relates to health, is no doubt a promising field of study. But it's a little too early to start prescribing diets based on a person's genome. Nonetheless, plant-based diets with plenty of fruits, vegetables, beans, whole grains and moderate amounts of lean proteins are nutritious for everyone. And calories still count. Just because a particular food may be considered healthful, doesn't mean it is calorie free. Balance is key here."
Nikhil Dhurandhar, Ph.D., professor and chair of the department of Nutritional Sciences, Texas Tech University, Lubbock, Texas, suggested via email that, “Epigenetics is a potentially powerful mechanism that could eventually be harnessed for regulating genetic expression. At the moment, however, we are largely at the level of “describing” than "regulating" the phenomenon.” Using a simple analogy, he cautions that right now we are not nearly at the point of selectively encouraging “the growth of certain (desired) trees without affecting (the growth or behavior of) all the other trees in the jungle.” (sent to me by email)
It does appear that efforts to identify best dieting practices for weight loss and optimal health is in its infancy but surely science is moving along to identify best practices that will eventually herald your best diet option for a variety of different health goals.