December 19th, 2013
More Walking and More Fiber: Good for the Heart
It probably won’t come as a surprise, but walking more and eating more fiber are probably good for your heart. That’s the conclusion of two new studies, but because the studies relied on observational data it should be emphasized that they are incapable of demonstrating cause and effect. And it’s by no means clear that most people are willing to undertake the effort needed to achieve effective lifestyle changes like these.
In the first study, published in the Lancet, researchers analyzed data from 9,300 people with impaired glucose tolerance (and therefore at high risk for developing diabetes) and with existing cardiovascular disease or at high risk for CV disease. (The patients were participants in a trial, known as NAVIGATOR, that tested two different drugs.) Study participants were followed for 6 years. Walking was measured with a pedometer at the beginning of the study and at one year.
The amount of walking at baseline, and the change in walking at one year, were both inversely associated with the risk of having a cardiovascular event. For every 2000 steps per day at baseline — which is equivalent to about 20 minutes of walking — the risk of cardiovascular events was reduced by 10%. At one year, every additional 2000 steps per day was associated with a further 8% reduction in cardiovascular risk. The association persisted even after adjusting for a wide range of confounding factors, including weight, smoking status, diet, and use of other drugs.
In an accompany comment, Giuseppe Pugliese and Stefano Balducci write that the finding “adds compelling and reassuring evidence for the benefits of physical activity on cardiovascular health, although further observational and intervention studies with rigorous and objective assessment of physical activity and fitness are needed.”
In the second paper, published in BMJ, investigators performed a systematic review of studies examining the effect of dietary fiber on cardiovascular and coronary heart disease. They reported a significant 9% reduction for both CVD and CHD for every additional 7 grams of total fiber consumed each day. (Seven grams is the equivalent of 2-4 serving of fruit and vegetables or one portion of whole grains and one portion of beans or lentils.) The authors said that they only included studies of fiber contained in the diet and cautioned that their findings should not be applied to fiber supplements.
In an accompanying comment, Robert Baron writes that “clinicians should enthusiastically and skillfully recommend that patients consume more dietary fiber.” Current estimates are that most people in Western countries only consume about half of recommended amounts of dietary fiber.
But it’s one thing to show that walking more and eating more fiber are good for you. It’s another thing entirely to actually figure out how to get people to do these things. In his comment, Baron points out that “persuading patients to eat whole grains is particularly challenging.” Undoubtedly, getting people to exercise is even more difficult. Just earlier this year the Look Ahead trial found that an intensive lifestyle intervention was no better than standard care in reducing cardiovascular events in people with type 2 diabetes.