It's something that happens to all of us as we age. Our arteries – the vessels that deliver oxygen-rich blood to our tissues – stiffen and lose their ability to easily expand and contract.
Having stiffer arteries increases the risk of high blood pressure, heart attack, stroke and cognitive decline even among people who don't have outward symptoms of cardiovascular problems.
According to a report that will be published in the February issue of The American Journal of Clinical Nutrition, the foods you eat – and don't eat – can help keep your arteries young by reducing stiffness.
According to the review, an analysis of 38 randomized controlled trials, fish oil supplements and soy foods slow down how fast your arteries age, while caffeine and salt seem to accelerate the damage.
With age our artery walls accumulate collagen, a protein that glues the arteries together, making them more rigid. And the cells that line our arteries produce less nitric acid, a gas that relaxes and dilates blood vessels. The net result: less elastic arteries that are more challenged to push blood through them.
Age isn't the only factor in the deterioration of arteries. Smoking, high blood pressure, high LDL cholesterol, diabetes, obesity and lack of exercise all exacerbate the situation.
Arterial stiffness can't be measured at your doctor's office, at least not yet. In clinical studies, researchers measure something called pulse wave velocity (PWV) to determine the stiffness of participants' arteries.
PWV is the time it takes a pulse to travel between two points; the greater the velocity, the stiffer the arteries. It's a strong predictor of future heart problems and cardiovascular death.
While we don't yet have proof that reducing artery stiffness will ward off heart attack, stroke or memory problems, there's certainly evidence that the following dietary modifications can help keep your arteries flexible as you age. And that means a healthier heart.
Add fish oil
Long-term fish oil supplementation has consistently been shown to reduce artery stiffness. Omega-3 fatty acids in fish oil – called DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid) – are thought to improve artery flexibility by reducing inflammation, blood clotting and blood vessel constriction.
In the latest review of studies, a daily dose of 900 milligrams of EPA and DHA combined provided the largest benefit. This amount can be achieved by eating six ounces of Atlantic salmon a week.
If you don't like fish, supplements are an alternative. Fish oil capsules (one gram each) vary in dosage. Some provide 300 milligrams of EPA plus DHA, but others have 500 or 600 milligrams. (Check the label – details are usually in fine print on the back.). Liquid fish oil can deliver as much as 1,300 milligrams of EPA plus DHA a teaspoon.
In the review, all but one study demonstrated the ability of soy to reduce arterial stiffness, perhaps explaining in part why populations who consume high amounts of soy have less heart disease.
Soybeans are a rich source of isoflavones, phytochemicals thought to protect blood vessels from damage. Research suggests that consuming at least 80 milligrams of isoflavones a day offers protection.
Good sources of isoflavones include cooked soybeans (½ cup equals 33 mg), soy nuts (two tablespoons equals 32 mg), soy beverage (one cup equals 25 mg), firm tofu (½ cup equals 27 mg) and soy yogurt (¾ cup equals 50 mg).
Drink black tea
Lab research suggests that antioxidants in black tea (orange pekoe, for example), called flavonoids, reduce artery stiffness. Flavonoids have been shown to increase the production of nitric oxide, which helps arteries relax.
Green tea, also a rich source of flavonoids, has not been studied in relation to arterial stiffness but there's no reason to think that its antioxidants wouldn't have the same effect.
Increase fruits and vegetables
If you have hypertension, eating more fruit and vegetables can improve the elasticity of your arteries. A 2009 study found that people who ate the most fruit and vegetables – six servings a day – scored highest on arterial function. Even eating one additional daily serving had a beneficial effect.
Aim to get at least seven servings of fruit and vegetables each day. One serving is a medium-sized fruit, ¼ cup dried fruit, ½ cup of cooked vegetables, one cup of salad greens or ½ cup vegetable or 100-per-cent fruit juice.
Excess sodium increases artery stiffness. Consuming less sodium reduces stiffness by lowering elevated blood pressure and affecting chemicals that control how arteries relax and contract.
Adults under 50 need 1,500 milligrams of sodium a day, people aged 50 to 70 need 1,300 mg, and older individuals need 1,200 mg. (With age, the body becomes more sensitive to the blood-pressure-raising effects of sodium.) The upper daily sodium limit – an amount we should all strive to consume less of – is 2,300 mg.
Read nutrition labels on packaged foods and choose brands with lower amounts of sodium a serving. A daily value of 5 per cent or less for sodium means one serving of the food is low in sodium.
Consuming 80 to 300 mg of caffeine – found in one to three cups (eight ounces each) of coffee – can increase artery stiffness temporarily in healthy people.
The effects of daily caffeine consumption on blood vessel function over the long term isn't known, but the evidence shows that minimizing caffeine can reduce artery stiffness.
Control your weight
Studies demonstrate that gaining weight makes arteries stiffer while losing excess weight improves the ability of arteries to relax and contract.
The best way to manage your weight is to monitor your calorie intake and get regular aerobic exercise (e.g. brisk walking, jogging, cycling). Folks who participate in regular aerobic exercise have more flexible arteries than those who don't. This type of exercise may even reverse artery stiffness once it's set in.
Leslie Beck, a Toronto-based dietitian at the Medcan Clinic, is on CTV's Canada AM every Wednesday. Her website is lesliebeck.com.