Eating more fiber may lower your risk of death from cardiovascular, infectious, and respiratory diseases, a huge study published in this issue of Archives of Internal Medicine concludes. Data from almost 600,000 people aged 50-71 from 6 US states and 2 metropolitan areas were gathered as part of the NIH-AARP Diet and Health Study. Study participants were followed for an average of 9 years and after excluding those with pre-existing heart disease, cancer, diabetes and other health conditions, almost 400,000 remained. Those who consumed the most fiber reduced their risk of death from cardiovascular, infectious and respiratory disease the most.
As Rick and I agree in this week's podcast, this is yet one more intervention that's easy to employ, puts power in the hands of patients and has the potential to have a big impact. How much fiber did study subjects need to consume to reduce their risk of death? A benefit was seen when 10 grams of fiber were consumed per 1000 calories, with current recommendations calling for 14 grams per 1000 calories for maximum benefit.
This study further delineated the type of fiber that was most beneficial: that from whole grains. Fiber from vegetables and that from fruits respectively was less helpful, underscoring once again the notion that picking foods as close as possible to those found in nature is likely to be the best choice. Vegetables and fruits fit into that paradigm, and I would love to see a study that would explain why fiber found from these sources isn't as helpful as that in whole grains. The authors suggest that a diet largely based on whole grains, vegetables and fruits should be of maximum benefit.
What is it about fiber that helps improve heart and blood vessel disease risk, infections and respiratory conditions? Previous studies on dietary fiber have shown that it improves cholesterol profiles, perhaps by binding cholesterol and allowing it to be excreted, it slows down absorption of glucose and others nutrients from foods after eating, thus avoiding a spike in blood sugar and the need for a large amount of insulin to be released as a result, and it also lowers blood pressure. These effects would help explain its positive impact on cardiovascular disease.
Regarding respiratory disease and infections, fiber is known to reduce inflammatory factors found in the blood, and previous studies have also demonstrated a role for fiber in reducing risk by this mechanism. Clearly, consuming fiber from whole grains is a must for a healthy diet for all concerned.
What about fiber and cancer risk? This study found a positive impact on reducing cancer risk in men but not in women, with previous studies having some conflicting results. My take home message from this though is that since fiber so clearly has benefits in a range of other diseases, it's well worth adding to the daily routine.
Besides a study on why vegetables and fruits don't help as much as whole grains, I would also like to see a study comparing fiber supplements with that found in the whole food. Since supplements are usually manufactured from grains and plants I wonder if they would work as well. My other thought on this though is we are seeing a body of evidence accumulating that whole foods are preferable to supplements virtually all the time. My suspicion is that whole foods that are high in fiber would also be better for weight control, thus diabetes risk and so on.
Other studies this week include medical device recalls and the role of the FDA, also in Archives, the relationship between obesity, knee osteoarthritis, morbidity and death in Annals of Internal Medicine, and whether kids can take asthma medications only when needed in the Lancet. Until next week, y'all live well.