Can you protect your DNA from damage through diet?
Diet can both protect and damage your DNA, but the protective effects of supplements often fall short in practice. Make sure you are not deficient in zinc, folate and selenium, eat plenty of vegetables and fruit, and avoid supplements containing high doses of beta-carotene, especially if you smoke.
Diet has a real influence on the amount of DNA damage in your cells, but the story is more nuanced than 'eat more antioxidants and your DNA is safe'. Some substances in food actively damage DNA. Mould toxins in spoiled grains, substances released when meat is heated at high temperatures, and combustion products in charred food react directly with your DNA and cause mutations. This is the most harmful side of the diet-DNA relationship.
On the protective side, there are a few specific associations. Carotenoids, the pigments that give vegetables and fruit their orange, yellow and green colours, are linked to less DNA damage in white blood cells. Getting enough zinc is important: a significant zinc deficiency demonstrably leads to more DNA breaks, and zinc plays a role in more than 300 proteins, including repair mechanisms. The same applies to folate (a B vitamin) and selenium: a structural deficiency in either makes DNA more susceptible to errors during cell division. Brussels sprouts are one of the few foods for which a dietary study showed a measurable effect on DNA damage.
With general dietary interventions and antioxidant supplements, however, the results are disappointing. Across multiple studies, no consistent measurable effect on oxidative DNA damage has been demonstrated. This refers to supplements and broad dietary adjustments, not to the correction of the specific deficiencies mentioned above. Furthermore, smoking contributes 35 to 50 percent more oxidative DNA damage, as measured in urine. No dietary pattern fully compensates for that.
A serious warning: high doses of beta-carotene as a supplement turned out to increase the risk of lung cancer in smokers, whereas beta-carotene from vegetables and fruit caused no problem whatsoever. Supplements are therefore not the same as food, and more is emphatically not better here. Vitamin C also has a lesser-known downside: under certain laboratory conditions it acts as a pro-oxidant and can cause damage, although it is unclear whether this is practically relevant in the living body.
This answer is based on multiple reviews of studies in humans and in the laboratory. The findings on smoking and beta-carotene as a supplement are well supported by intervention studies. The associations with carotenoids, zinc, folate and selenium come from research in which people were followed for years or in which intake was measured, but where cause and effect have not always been conclusively proven. The findings on plant polyphenols come only from laboratory research outside the human body. Across the majority of antioxidant supplements and dietary interventions in general, multiple studies show disappointingly little effect.
Can you counteract DNA damage from ageing through your lifestyle?
Quitting smoking, exercising regularly and eating plenty of vegetables demonstrably reduce DNA damage; antioxidant supplements are unlikely to help with this.
Can you repair DNA damage, or can you only prevent it?
Your body actively repairs DNA damage through multiple well-studied mechanisms, but that repair is not always perfect and becomes less effective when the cell is under excessive strain or grows older.
Can DNA damage in your cells repair itself?
Your cells repair DNA damage continuously and systematically, but the system is not infallible: chronic overload or a defect in the repair pathways increases the risk of cancer and age-related diseases.
How do telomeres protect your DNA?
Telomeres protect your chromosome ends through a system of proteins that simultaneously prevents false alarms and harmful fusions. If that system fails due to inherited defects, you can develop serious ageing-related diseases.
Can smoking permanently damage your DNA?
Smoking damages your DNA in multiple ways simultaneously, and some of that damage is permanent; quitting genuinely helps, but does not erase earlier mutations.
What does a vitamin D deficiency do to your DNA?
A vitamin D deficiency is associated with greater DNA damage, especially in people with an additional risk factor. Make sure your vitamin D level is adequate, but if you are unsure about supplementation, consult your general practitioner.