Doctor’s Tip: DNA, one of the body’s 5 defense mechanisms
This column is about the fifth of Dr. William Li’s five body defense mechanisms, from his book “Eat to Beat Disease, The New Science of How Your Body Can Heal Itself.” The human body contains some 37 trillion cells. Each cell contains 46 chromosomes, made up of two strands of bunched-up DNA, in the form of a double helix. Three percent of DNA makes up our genes, and the other 97 percent serves as a template to make the 10,000 proteins that are necessary for life.
Your DNA gets more than 10,000 DNA-damaging hits every day, some of which are spontaneous due to chance “when trillions of cells are working and replicating nonstop…” Others are caused by factors noted in the paragraph below. If these genetic hits occur to a man’s sperm or a woman’s ovum (“egg”), abnormalities in progeny can occur. DNA damage to non-reproductive cells is linked to several diseases, including Alzheimer’s, atherosclerosis, autism, all types of cancer, depression, diabetes, inflammatory bowel disease, obesity, Parkinson’s, PTSD, rheumatoid arthritis, schizophrenia and lupus.
The following are some of the factors that can damage DNA: age, inflammation, free radicals (oxidation), infection (e.g. liver and cervical cancer result from viral infections), ultraviolet radiation from the sun, radiation from medical imaging, radon from the ground, tobacco smoke, air pollution, toxic chemicals in our environment, and emotional stress. Dr. Li notes that “our cells have evolved with powerful repair processes. … This prevents the vast majority of abnormalities that might develop in our DNA from being passed on when DNA replicates itself.”
Anti-oxidants in food (but not in supplement form) destroy free radicals, which helps prevent DNA damage, but doesn’t repair it once it occurs. One way damaged DNA gets repaired is through enzymes that recognize abnormalities and replaces them with normal parts. Due to DNA repair enzymes, “fewer than one of every one thousand errors introduced to our DNA are estimated to become permanent mutations…” If there is too much damage to fix, cell self-destruction occurs, called apoptosis.
Telomeres are another form of DNA defense and repair. These are caps on the end of DNA strands, that keep the DNA from shortening and unraveling. Telomerase is an enzyme that continually repairs telomeres. Smoking, stress, poor sleep, unhealthy diet and lack of exercise damage telomeres.
One way DNA protects us is through epigenetics — turning genes on and off through our environment such as what we eat and physical activity. There is a saying in medicine that speaks to this: “Genetics loads the gun but environment pulls the trigger.” A healthy lifestyle with proper diet and regular exercise turns on many health-promoting genes, whereas an unhealthy lifestyle turns off these genes and turns on disease-promoting genes.
Foods that positively influence DNA repair include spinach, carrots, red peppers, lentils, beans, mushrooms, kiwifruit, berries, broccoli, tomatoes, watermelon, guava and pink grapefruit. Foods that promote telomerase include soy, turmeric, coffee beans, tea, nuts and seeds. Foods with positive epigenetic effects include cruciferous vegetables, coffee, tea and turmeric. Exercise promotes DNA health as well. Dr. Li recommends avoiding the following foods for optimal DNA health: fatty foods, processed meat and sugar-sweetened beverages.
Dr. Li notes lab studies suggest that a few non-plant foods can promote DNA health as well: clams, oyster sauce, pacific oysters, tuna and yellowtail fish. However, positive lab studies don’t always translate into positive results in humans, and you can’t go wrong with just sticking to plants.
Next week’s column will be the last in this series about Dr. Li’s book and will be about protecting yourself from the top killers.
Greg Feinsinger, M.D. is a retired family physician who has a nonprofit: Prevention and Treatment of Disease Through Nutrition. He gives a free presentation at 7 p.m. the first Monday of the month at the Third Street Center in Carbondale; is available by appointment for free consultations (379-5718); and conducts a shop-with-a-doc session at 10 a.m. the first Saturday of the month at Carbondale City Market.
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