by Craig Weatherby
The standard American diet—aptly acronymed SAD—is overloaded with refined, nutrient-poor, nearly fiber-free white flour and corn starch.
And that's one major reason, along with an excess of sugars and omega-6 vegetable fats, why the SAD pattern is proven unhealthful.
In contrast, most studies published to date link diets featuring moderate-to-ample amounts of whole, unrefined grains to better heart and overall health.
In part, this may be due to the polyphenol “antioxidants” that abound in whole wheat, rice, oats, barley, corn, and other unrefined grains… amounts that rival those found in berries, grapes, cocoa, and tea.
(See “Whole Grain Foods Found High in Antioxidants.” Buckwheat is also high in polyphenols, but it's actually a fruit, not a grain. And the polyphenols in foods may not bring their benefits by exerting direct antioxidant effects in the body, but instead via “nutrigenomic” influences on key gene switches in our cells… see “Food-Borne Antioxidants May Act Indirectly.”)
Fiber also plays a role in the healthful reputation of whole grains… and a new analysis of data from America's largest diet-health study affirms and expands on prior findings.
Largest diet study ever conducted
Their study examined data gathered from more than 500,000 men and women participating in the NIH-AARP Diet and Health Study, which was the largest study of diet and health ever conducted. (NIH stands for (National Institutes of Health; AARP stands for American Association of Retired Persons.)
From 1995 through 1996, researchers mailed 3.5 million questionnaires to AARP members aged 50-71.
The survey included questions about diet and lifestyle, including history of smoking, physical activity, family history of cancers, hormone therapy use in women, and some medical conditions.
Whole grains appear to deter death
Researchers at the U.S. National Cancer Institute and the AARP analyzed data from more than a half-million Americans who completed surveys and were then followed for nine years.
The results showed a significant link between higher intake of fiber from grains and lower risk of death from any cause—including cardiovascular disease (CVD), cancer, and respiratory disease—in both men and women.
Comparing the highest with the lowest intake of fiber from grains, men had a 23 percent lower risk of death and women had a 19 percent lower risk of death.
As the authors concluded, “Dietary fiber may reduce the risk of death from cardiovascular, infectious, and respiratory diseases. Making fiber-rich food choices more often may provide significant health benefits” (Park Y et al. 2011).
Higher fiber intake was also associated with lower risk of death in former and current smokers and across all categories of body mass index (BMI).
Diets high in grain fiber were also associated with lower risk of death from cardiovascular, infectious, and respiratory diseases… 24 to 56 percent lower in men and 34 to 59 percent lower in women.
Interestingly, the association between higher grain-fiber intake and reduced risk of cancer death was seen only in men, and not in women.
Three years ago, the same team concluded that diets high in fiber from whole grains, but not from other foods, reduced the risk of colon cancer by 14 percent (Schatzkin A et al. 2008).
The researchers said fiber from vegetables and beans was also weakly associated with a lower risk of death in both men and women.
Surprisingly, fiber from fruits was not related to a reduced death risk in men or women.
The researchers said that their study offered superior statistical power, noting that previous studies suffered from small sample sizes, narrow ranges of dietary fiber intakes, and inadequate controls for confounding factors.
Park Y, Subar AF, Hollenbeck A, Schatzkin A. Dietary Fiber Intake and Mortality in the NIH-AARP Diet and Health Study. Arch Intern Med. 2011 Feb 14. [Epub ahead of print]
Schatzkin A, Mouw T, Park Y, Subar AF, Kipnis V, Hollenbeck A, Leitzmann MF, Thompson FE. Dietary fiber and whole-grain consumption in relation to colorectal cancer in the NIH-AARP Diet and Health Study. Am J Clin Nutr. 2007 May;85(5):1353-60.