It’s well established that a healthy eating pattern, plentiful in plant foods, plays a key role in preventing cardiovascular disease. Many studies have tied the Mediterranean, vegetarian and DASH diets, for example, to a lower risk of heart disease and stroke.
Now, new research suggests that when choosing foods, it’s also important to consider their potential to increase or dampen inflammation in the body.
According to researchers from the Harvard T.H. Chan School of Public Health, eating a diet high in proinflammatory foods significantly increases the risk of cardiovascular disease.
The findings also indicate that including unique anti-inflammatory foods in a heart-healthy diet may bolster its cardio-protective effects.
Inflammation and heart disease
For the short-term, inflammation is helpful. It’s part of the body’s immune response to heal wounds and fight infection.
If inflammation persists, however, excessive inflammatory immune compounds are released that can increase illness. Chronic inflammation can promote the build-up of fatty plaques in artery walls, rupture plaques and trigger blood clots that could lead to heart attack or stroke.
While previous research has linked healthy diet patterns to lower levels of inflammation, it’s not known whether long-term adherence to a proinflammatory diet increases the risk of cardiovascular disease.
The latest research
To answer this question, Harvard investigators followed 210,145 American men and women for up to 32 years. At the study outset, participants were free of coronary heart disease and stroke.
Health and lifestyle information was collected every two years and diet intake was assessed every four years. Participants' diets were assigned a food-based dietary inflammatory score to indicate its potential to increase inflammation.
Dietary inflammatory scores were based on 18 food groups shown to have the strongest association with inflammatory markers in the bloodstream. A higher score indicates proinflammatory diets, and a lower score indicates anti-inflammatory diets.
The results, published this month in the Journal of the American College of Cardiology, revealed that people who consumed proinflammatory diets had a 46 per cent higher risk of coronary heart disease and a 28 per cent higher risk of stroke, compared with those who ate anti-inflammatory diets. And the higher the inflammatory potential of the diet, the greater the risk of cardiovascular disease.
A higher dietary inflammatory score was also associated with higher blood levels of inflammatory immune compounds.
To arrive at these results, the researchers controlled for other cardiac risk factors, including age, body weight, physical activity, hypertension, high cholesterol and diabetes.
One strength of the study is that diet and lifestyle factors were assessed repeatedly throughout the follow-up period. This allowed researchers to capture changes in participants' diets and risk factors.
The study’s observational design, however, can’t prove that a proinflammatory diet causes cardiovascular disease. The study was performed among health professionals who were mostly white, so the findings may not apply to other populations.
What to eat, what to limit
Major food contributors to higher dietary inflammatory scores were refined sugars, refined grains, sugary drinks, fried foods, processed meats (e.g., sausage, salami, bacon), red meat (e.g., beef, lamb, pork) and organ meats.
Participants with lower dietary inflammatory scores ate foods high in antioxidants and fibre.
The researchers recommended consuming green leafy vegetables (e.g. spinach, kale, Swiss chard, rapini, arugula, romaine lettuce), yellow vegetables (e.g. yellow peppers, yellow beans, carrots, pumpkin, butternut squash), whole grains, coffee, tea and wine. (If you do drink wine, limit yourself to one to two five-ounce glasses a day.)
Walnuts should be added to this list, too, according to a randomized controlled trial from Spain, also published this month in the same journal.
Among 634 participants, those who included 30 grams to 60 grams of walnuts (14 to 28 walnuts halves) in their daily diet for two years had significantly lower levels of inflammation in the body, compared with the people in the control group whose diets didn’t include walnuts.
Other foods with established anti-inflammatory properties include oily fish (e.g. salmon, trout, sardines, Arctic char), berries, pomegranate seeds, oranges, apples, pears and extra virgin olive oil.
Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan. Follow her on Twitter @LeslieBeckRD
Sign up for the weekly Health & Wellness newsletter for the latest news and advice.