If you don't consider your chromosomes when deciding what to eat, it may be time to start. A study published this month in the American Journal of Clinical Nutrition is the latest to signal that the foods you eat – and don't eat – may affect the length of your telomeres, a marker of biological aging.
Telomeres are protective caps of DNA and protein on the ends of chromosomes. Like the plastic tips on the ends of shoelaces, telomeres prevent the ends of chromosomes from fraying. In doing so, they keep our genetic data intact.
Yet every time cells divide – which is crucial for producing new skin, blood, bone and other cells – their telomeres get progressively shorter until they can no longer divide and eventually die.
Shorter telomeres have been associated with coronary heart disease, stroke, diabetes, dementia, osteoporosis and many types of cancer. Some studies have linked shorter telomeres with early death.
The length of your telomere decreases as you age. But the fact that telomere length varies considerably between individuals of the same age suggests that, in addition to heredity, environmental and lifestyle factors may play a role.
Chronic inflammation and oxidative stress are thought to accelerate telomere shortening. Lifestyle factors that increase the production of inflammatory chemicals and harmful free radicals – e.g., smoking, psychological stress, poor diet, increased waist circumference – have been correlated with shorter telomeres.
The Spanish researchers behind the most recent study set out to determine whether diet-related inflammation could alter the rate of telomere erosion in 520 adults, ages 60 to 80, who were at high risk of cardiovascular disease. They measured the length of telomeres in white blood cells at the beginning of the study and five years later.
An anti-inflammatory diet is not a "diet" in the usual sense of the word. Rather, it's a way of choosing foods – and limiting or avoiding others – to help dampen inflammation in the body.
A diet plentiful in vegetables, fruit, whole grains, nuts and seeds, healthy oils and fish appears to reduce inflammation and the risk of inflammation-related diseases such as atherosclerosis, rheumatoid arthritis, asthma and inflammatory bowel disease (e.g., Crohn's disease, ulcerative colitis).
A high intake of meat, refined (white) grains, added sugars and foods rich in saturated and trans fats has been shown to promote inflammation. Many pro-inflammatory foods also contribute to weight gain, which itself can trigger inflammation.
In the study, participants' diets were analyzed and scored according to whether they promoted inflammation, reduced inflammation or had no effect on inflammatory markers in the bloodstream. (The scoring system was based on previous research that measured the effect of foods on inflammatory proteins in the bloodstream.)
At the start of the study, people who ate a more anti-inflammatory diet had longer telomeres. And the greater a participants' anti-inflammatory diet score, the slower the rate of telomere-shortening over the five years.
Participants with the highest pro-inflammatory diet scores, on the other hand, had almost a two-fold greater risk of accelerated telomere erosion compared with those with the highest anti-inflammatory diet scores.
These findings suggest diet-related inflammation hastens telomere shortening and that an anti-inflammatory diet puts the brakes on telomere erosion. But they don't prove it. The researchers didn't measure inflammation in participants and therefore weren't able to confirm that inflammation – and not something else – was responsible for telomere shortening.
Even so, the findings add to growing evidence linking diet to telomere length. Previous studies have revealed that a higher intake of specific dietary components – including fibre, antioxidants, omega-3 fatty acids, vitamins C and E and polyphenols (plant chemicals in many fruits and vegetables) – are associated with longer telomeres.
For example, a 2014 study from Brigham and Women's Hospital and Harvard Medical School in Boston found that greater adherence to a Mediterranean diet – known for its abundance of anti-inflammatory and antioxidant compounds – was tied to longer telomeres.
Whether an anti-inflammatory diet extends the lifespan of your cells remains to be proved, but it can certainly keep you healthy in other ways. After all, it's the same dietary advice that guards against heart disease, stroke, Type 2 diabetes, Alzheimer's, certain cancers and obesity.
Leslie Beck, a registered dietitian, is based at the Medisys clinic in Toronto.
How to up your anti-inflammatory consumption
The following foods can rev up the anti-inflammatory capacity of a healthy diet.
Canned sockeye salmon: It's packed with anti-inflammatory omega-3 fatty acids. Plus, salmon, especially sockeye, is one of the few foods that offer a generous amount of vitamin D (730 international units per three ounces). People with higher blood vitamin D levels have been found to have longer telomeres. Also eat: mackerel, trout, canned tuna, herring, sardines.
Carrot juice: Just one-half cup of carrot juice packs in 11 milligrams of beta-carotene, a phytochemical shown to reduce inflammation in animal studies. It's also a source of lutein and alpha-carotene, other inflammation-fighting carotenoids. Juice it yourself or buy an unsweetened brand to cut added sugars. Also eat: carrots, sweet potato, pumpkin, spinach, kale, collard greens, winter squash.
Pumpkin seeds: People who eat nuts and seeds frequently – versus rarely or never – have lower levels of inflammation. Pumpkin seeds, though, deliver the most magnesium, a mineral that contributes to their inflammation-quelling potential (a 1/4 cup supplies half a day's worth). Other anti-inflammatory compounds in pumpkin seeds include fibre and arginine, an amino acid. Also eat: almonds, Brazil nuts, cashews, hazelnuts, peanuts, pecans, pistachios, walnuts.
Green tea: This healthy beverage is an exceptional source of catechins, a type of flavonoid with potent anti-inflammatory properties. A cup of green tea brewed from loose tea leaves contains more catechins than one brewed from a tea bag due to the greater surface area. (Tea leaves have more surface area than a tea bag for hot water to extract the antioxidants.) Also drink: black tea, white tea, oolong tea.
Hulled (dehulled) barley: To increase your intake of inflammation-fighting fibre, eat barley more often. Three-quarters of a cup delivers eight grams of fibre, twice as much as the same amount of quinoa. Barley also scores very low on the glycemic index scale, so it doesn't spike blood sugar and insulin. Also eat: steel cut and large flake oats, brown rice, quinoa, bulgur .
Herbs and spices: Many herbs and spices contain anti-inflammatory polyphenols including basil, rosemary, cayenne pepper, ginger and turmeric. But the active ingredients in herbs and spices degrade over time. Store dried herbs and spices in airtight containers away from heat and direct sunlight.