A recent round of studies looking at potential health benefits from four nutrients or food groups—chocolate, olive oil, whole grains and vitamin D—show that making small yet significant changes to your diet can reduce the risks of certain chronic diseases while protecting you from others.
Dark chocolate is more than delicious, it’s been touted as a mood booster because of some naturally occurring chemicals. For people with hypertension, eating dark chocolate may also help to reduce blood pressure levels. Researchers writing in the open access journal BMC Medicine combined the results of 15 studies on the effects of flavanols (compounds in chocolate that cause dilation of blood vessels) on blood pressure.
"Flavanols have been shown to increase the formation of endothelial nitric oxide, which promotes vasodilation and consequently may lower blood pressure. There have, however, been conflicting results as to the real-life effects of eating chocolate. We’ve found that consumption can significantly, albeit modestly, reduce blood pressure for people with high blood pressure but not for people with normal blood pressure," reported Dr. Karin Ried, who worked with a team of researchers from the University of Adelaide, Australia, on the analysis.
The pressure reduction seen in the combined results for people with hypertension—5mm Hg systolic—may be relevant. It’s right within the benefit range of getting 30 minutes of physical activity every day (4-9mm Hg) and could, in theory, reduce the risk of a cardiovascular event by about 20 percent over five years. The researchers are cautious, however: "The practicability of chocolate or cocoa drinks as long-term treatment is questionable," said Dr. Ried.
What you might consider: Eating one ounce of dark chocolate a day—remember that chocolate is still high in fat, so you don’t want to overdo it.
Note: The full article is available at the BMC journal website http://www.biomedcentral.com/1741-7015/8/39/
According to a report from a team of researchers, compounds called the phenols in olive oil actually modify genes that are involved in the inflammatory response. The researchers knew from other studies that consuming high-phenolic-content virgin olive oil reduces pro-inflammatory, pro-oxidant and pro-blood-clotting biomarkers when compared with consuming low-phenolic-content olive oil (from later pressings of the olives). But they wanted to know whether olive oil’s beneficial effects could be the result of gene activity. The study, published recently in Biomed Central (BMC) Genomics, was done by a multi-institute group of researchers headed by Francisco Perez-Jimenez with the University of Cordoba, Spain. Among the researchers was USDA’s Agricultural Research Service computational biologist Laurence Parnell, with the Nutrition and Genomics Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging (HNRCA) at Tufts University in Boston, Mass.
For the study, the researchers fed 20 volunteers who had the medical condition called metabolic syndrome two virgin olive oil-based breakfasts one at a time, after a six-week “washout” period. (Metabolic syndrome is a prevalent condition often characterized as a combination of belly fat, high triglycerides, high blood pressure and poor blood sugar control, all of which increase the risk for heart disease and diabetes.) One of the breakfasts contained virgin olive oil with high-content phenolic compounds (398 parts per million) and the other contained olive oil with low-content phenolic compounds (70 parts per million). All volunteers consumed the same low-fat, carbohydrate-rich “background” diet during both study phases. The researchers tracked the expression of more than 15,000 human genes in blood cells during the after-meal period. The results indicated that 79 genes are turned down and 19 are turned up by the high-phenolic-content olive oil. Many of those genes have been linked to obesity, high blood-fat levels, type 2 diabetes and heart disease. Importantly, several of the turned-down genes are known promoters of inflammation, so those genes may be involved in “cooling off” inflammation that often accompanies metabolic syndrome. The researchers concluded that the results shed light on a molecular basis for reduced heart disease risk among people living in Mediterranean countries where virgin olive oil is the main source of dietary fats.
What you might consider: To get the highest phenol count, choose extra virgin olive oil, which is made from the first pressing of the olives.
ARS-funded scientists have also recently contributed to the limited but growing body of evidence of a link between vitamin D and cognitive function. Cognitive function is measured by the level at which the brain is able to manage and use available information for activities of daily life. Alzheimer’s disease, the most common form of age-related dementia, affects about 47 percent of adults aged 85 years or older in the United States. Identifying nutritional factors that lower cognitive dysfunction and help preserve independent living provides economic and public health benefits, according to authors. The study, which was supported by ARS and the National Institutes of Health among others, was led by epidemiologist Katherine Tucker with the Jean Mayer USDA Human Nutrition Research Center on Aging (HNRCA) at Tufts University in Boston. Tucker collaborated with HNRCA laboratory directors Irwin Rosenberg, Bess Dawson-Hughes and colleagues.
Metabolic pathways for vitamin D have been found in the hippocampus and cerebellum areas of the brain involved in planning, processing and forming new memories. This suggests that vitamin D may be implicated in cognitive processes. The study involved more than 1,000 participants receiving home care. The researchers evaluated associations between measured vitamin D blood concentrations and neuropsychological tests. Elders requiring home care have a higher risk of not getting enough vitamin D because of limited sunlight exposure and other factors.
The participants, ages 65 to 99 years, were grouped by their vitamin D status, which was categorized as deficient, insufficient or sufficient. Only 35 percent had sufficient vitamin D blood levels, and they had better cognitive performance on the tests than those in the deficient and insufficient categories, particularly on measures of "executive performance," such as cognitive flexibility, perceptual complexity and reasoning. The associations persisted after taking into consideration other variables that could also affect cognitive performance.
What you might consider: While 10 minutes a day of sun exposure may be enough to stimulated the body’s own production of Vitamin D, other ways to get vitamin are through foods, including certain fish like salmon and fortified dairy products like low-fat milk, and paired with calcium in supplements.
In a new study from researchers at the Harvard School of Public Health (HSPH) eating five or more servings of white rice per week was associated with an increased risk of type 2 diabetes. In contrast, eating two or more servings of brown rice per week was associated with a lower risk of the disease. The researchers estimated that replacing 50 grams of white rice (less than 2 ounces, or just one third of a typical daily serving) with the same amount of brown rice would lower risk of type 2 diabetes by 16 percent. The same replacement with other whole grains, such as whole wheat and barley, was associated with a 36 percent reduced risk.
The study is the first to specifically examine white rice and brown rice in relation to diabetes risk among Americans, said Qi Sun, who did the research while at HSPH and is now an instructor of medicine at Brigham and Women’s Hospital in Boston. "Rice consumption in the US has dramatically increased in recent decades. We believe replacing white rice and other refined grains with whole grains, including brown rice, would help lower the risk of type 2 diabetes," said Sun.
Brown rice is superior to white rice when it comes to fiber content, minerals, vitamins and phytochemicals, and it often does not generate as large an increase in blood sugar levels after a meal. Milling and polishing brown rice removes most vitamins and minerals. In addition, milling strips away most of its fiber, which helps deter diabetes by slowing the rush of sugar (glucose) into the bloodstream.
The researchers, led by Sun, and senior author Frank Hu, professor of nutrition and epidemiology at HSPH, examined white and brown rice consumption in relation to type 2 diabetes risk in 157,463 women and 39,765 men participating in the Brigham and Women’s Hospital-based Nurses’ Health Study I and II and the Health Professionals Follow-up Study. The researchers analyzed responses to questionnaires about diet, lifestyle and health conditions, which participants completed every four years. They documented 5,500 cases of type 2 diabetes during 22 years of follow-up in NHS 1 participants, 2,359 cases over 14 years in NHS II participants, and 2,648 cases over 20 years in HPFS participants.
Sun and his colleagues found that the biggest consumers of white rice were less likely to have European ancestry or to smoke and more likely to have a family history of diabetes. Eating brown rice was not associated with ethnicity, but with a more health-conscious diet and lifestyle. In the analysis, researchers adjusted for a variety of factors that could influence the results, including age, body mass index, smoking status, alcohol intake, family history of diabetes and other dietary habits, and found that the trend of increased risk associated with high white rice consumption remained. Because ethnicity was associated with both white rice consumption and diabetes risk, the researchers conducted a secondary analysis of white participants only and found similar results.
Because brown rice consumption was low in the study population, the researchers could not determine whether brown rice intake at much higher levels was associated with a further reduction in diabetes risk. Substitution of other whole grains for white rice was more strongly associated with lowering diabetes risk. This observation, said the researchers, may result from more reliable estimates based on participants’ higher consumption of whole grains other than brown rice.
The current Dietary Guidelines for Americans, released by the US government, identifies grains, including rice, as one of the primary sources of carbohydrates and recommends that at least half come from whole grains. Americans are eating more rice, but it’s mostly white. "From a public health point of view, whole grains, rather than refined carbohydrates, such as white rice, should be recommended as the primary source of carbohydrates for the US population," said Hu, "These findings could have even greater implications for Asian and other populations in which rice is a staple food."
What you might consider: In addition to substituting brown rice for part or all of the white rice you eat, try barley, quinoa and bulgur as side dishes and eat whole grain breads, roll and crackers instead of products made from white, refined flour.