The study, published February 21 in Frontiers in Nutrition, examined data on vegetable consumption among 399,586 adults in the United Kingdom who were 56 years old on average and had never been diagnosed with heart disease. After 12 years of follow-up, participants experienced a total of 18,052 major cardiovascular events, such as heart attacks and strokes, and a total of 4,406 people died of cardiovascular disease. Overall, participants consumed an average of 2.3 tablespoons (tbsp) a day of raw vegetables and 2.8 daily tbsp of cooked vegetables. When researchers compared people with the highest vegetable intake to those with the lowest consumption, raw veggies were associated with an 11 percent lower risk of cardiovascular disease and a 15 percent lower risk of death by events like heart attacks and strokes. There didn’t appear to be any heart benefit associated with cooked vegetables. And the study also found that most of the protective effect of raw veggies might be explained by differences in participants’ overall health, lifestyle habits, and socioeconomic status. This doesn’t mean cooked vegetables are bad for us, or that they can’t be part of a heart-healthy diet, says Alice Lichtenstein, DSc, a professor of nutrition science and policy and the director of the cardiovascular nutrition laboratory at Tufts University in Boston. “Assessing the effect of an individual food, rather than an entire dietary pattern, does not provide the whole picture and may be misleading,” says Dr. Lichtenstein, who wasn’t involved in the study. The people who ate the most raw vegetables in the study did a lot of other things that are associated with better cardiovascular health outcomes and that may have made the impact of veggies on their own seem much smaller. Participants with the highest raw vegetable consumption, for example, were more likely to attend college, avoid smoking, get more exercise, get treatment if they had high cholesterol or high blood pressure, consume lots of fish and fruit, and minimize their consumption of red and processed meat. It’s also possible that the cooking methods people used made raw veggies appear much healthier by comparison, says Nour Makarem, PhD, an assistant professor of epidemiology at Columbia University’s Mailman School of Public Health in New York City. “Cooked vegetables are often consumed with seasoning and oils, thereby increasing sodium intake and making them more energy dense, which could increase the risk of heart disease,” says Dr. Makarem, who wasn’t involved in the study. “Cooking can also alter digestibility and bioavailability of nutrients.” One limitation of the study is that researchers lacked data on the specific types of vegetables people ate, how foods were prepared, what proportion of participants’ diets came from veggies, or how many total calories people consumed. In fact, the total vegetable intake people reported in the study was a fraction of what’s recommended by U.S. dietary guidelines: 2 to 3 cups daily for women and 3 to 4 cups daily for men. That’s a minimum of 32 tbsp for women and 48 tbsp for men; the average daily intake in the study was just 5 tbsp. The study participants are in good company, however. Only 1 in 10 adults get the minimum recommended daily amount of vegetables, according to the U.S. Centers for Disease Control and Prevention (CDC). “The take-home is that we all need to eat more vegetables, whether they are raw, cooked, steamed, sautéed, pureed, or roasted,” says Samantha Heller, RD, a senior clinical nutritionist at New York University Langone Medical Center in New York City, who wasn’t involved in the study.
