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Category: Science

Dietary Epigenetics: New Frontiers

By: Austin Perlmutter, MD, Medical Student, Miller School of Medicine

While we may be familiar with the dangers of eating too much sugar, the actual effects of this indulgence may be far more frightening than previously imagined. Certainly, science supports the idea that excess sugar consumption leads to weight gain, increases our chances of diabetes and heart disease, and portends worse health outcomes. But now, new data shows that sugar can harm us in a place we didn’t expect, by actually attacking our DNA.

To properly explain this fascinating research, let’s quickly review some biology basics. The human body is made up of roughly 37 trillion cells, our structural building blocks. The “brain” of the cell is called the nucleus, and the nucleus contains our DNA. For years, we’ve assumed that DNA was a product of our heritage, handed down from mother and father, a rigid pre-determinant of everything from our height to our mathematical skills. However, the revolutionary new field of epigenetics has lead to the discovery that what we do actually changes the way our DNA is used, that the choices we make can forever transform our genetic code

This means that the way we interact with the world changes our DNA, not just the other way around. More intriguing, one of the major ways we can change our DNA is by diet. For example, a study published in 2008 showed that exposing mice brains to as little as 6 hours of high blood sugar led to epigenetic changes that increased risk of vascular damage. These changes lasted even after 6 days of normal blood glucose, representing long-term damage after just a short blast of sugar. The research on long-term effects from short exposures is at the core of epigenetics. It’s furthered by data from another 2008 study published in the journal Diabetes. 

In this work, researchers showed that short periods of high blood glucose led to worse long term vascular changes than did sustained high blood glucose (a scary thought for the carbohydrate binger). Again, the underlying mechanism seems to be modification of the cell’s DNA, leading to the extended duration of this effect.

But there’s more. The most frightening data on this subject shows that high blood glucose may damage our telomeres; the ends of our DNA code. Considering that an undamaged telomere may be protective against cancer, death, and the very act of aging, any process that harms telomeres could put us at substantial risk. Data from the Journal of Nutrition, Health and Aging found that the higher the blood sugar, the more damage caused to the telomere and its associated DNA.

If we know that high levels of circulating glucose are trashing our DNA, it would make sense that diets low in glucose could have the opposite effect. Indeed, this is true. From the journal Science, the article “When Metabolism and Epigenetics Converge” relates the known neuroprotective benefits of a low carbohydrate diet to the epigenetic suppression of toxic oxidative stress. This benefit, which was also seen with calorie restrictive diets, seems to indicate that choosing meals lower in carbohydrates and lower in calories improves our brain cells’ ability to fight off damage, leading to healthier brains.

Reflect for a moment on our current dietary recommendations The US dietary guidelines recommend we get 65% of our daily calories from carbohydrates sources. Beyond the fact that most carbohydrate rich meals are converted into sugar as soon as they’re digested, Americans will average around 13-14% of calories a day from pure added sugar. It would seem we’re advocating for a dietary plan destined to harm our DNA. The good news is that the field of epigenetic has also identified substances capable of undoing DNA damage. Enter the epigenetic diet.

Essentially, the idea of epigenetic diet is to maximize the health of your DNA. This diet emphasizes compounds like the sulforaphane (found in broccoli), curcumin (found in turmeric), epigallocatechin gallate (found in green tea) and resveratrol (found in wine), and is designed to slow or potentially reverse damage to our DNA. The epigenetic activity of these chemicals may both prevent cancer formation and lead to decreased fat cells, as well as generally lower inflammation.3 In contrast to the negative effects of blood sugar on the brain, these chemicals may  actually lower risk of Parkinson’s Disease and cognitive decline, as well as slow the progression of Alzheimer’s disease. While it’s too soon to tell if the benefits of these compounds can ameliorate the toxic effects of high sugar, initial research is impressive.

Moving forward, the field of epigenetics is poised to explode. The more we learn about our genetic makeup, the more we can learn how our environment affects it. It’s rather scary and amazing that the choices we make in life change our DNA, but the power this connotes can also lead to empowerment. Realize that when you eat a food, you are triggering a ripple effect that penetrates all the way to your genetic code. Your silverware can quite literally be a gene-editing tool, for better or worse.

References:

1. El-Osta A, Brasacchio D, Yao D, Pocai A, Jones PL, Roeder RG, Cooper ME, Brownlee M. Transient high glucose causes persistent epigenetic changes and altered gene expression during subsequent normoglycemia. J Exp Med. 2008 Sep 29;205(10):2409-17. doi: 10.1084/jem.20081188. Epub 2008 Sep 22. Erratum in: J Exp Med. 2008 Oct 27;205(11):2683. PubMed PMID: 18809715; PubMed Central PMCID: PMC2556800.

2. Ceriello A, Esposito K, Piconi L, Ihnat MA, Thorpe JE, Testa R, Boemi M, Giugliano D. Oscillating glucose is more deleterious to endothelial function and oxidative stress than mean glucose in normal and type 2 diabetic patients. Diabetes. 2008 May;57(5):1349-54. doi: 10.2337/db08-0063. Epub 2008 Feb 25. PubMed PMID: 18299315.

3. Maeda T, Oyama JI, Higuchi Y, Arima T, Mimori K, Makino N. The correlation between the telomeric parameters and the clinical laboratory data in the patients with brain infarct and metabolic disorders. J Nutr Health Aging. 2010 Nov;14(9):793-7. PubMed PMID: 21085912.

4. Sassone-Corsi P. Physiology. When metabolism and epigenetics converge. Science. 2013 Jan 11;339(6116):148-50. doi: 10.1126/science.1233423. PubMed PMID: 23307727.

5. U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES, Consumption of Added Sugars Among U.S. Adults, 2005–2010 R. Bethene Ervin, Ph.D., R.D., and Cynthia L. Ogden, Ph.D., M.R.P.

6. Martin SL, Hardy TM, Tollefsbol TO. Medicinal chemistry of the epigenetic diet and caloric restriction. Curr Med Chem. 2013;20(32):4050–4059.

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