In the News: Focus on Flavonoids, Vitamin D & Diabetes

A Key Component of Fruits and Veggies

Naturally occurring plant pigments, flavonoids are one of the reasons fruits and vegetables – from blueberries to onions – are so healthful. Eating more flavonoid-rich foods or drinking flavonoid-laden beverages such as green tea and wine, has been linked to a lower risk of chronic diseases including heart disease and stroke.

Some flavonoids act by corralling cell-damaging free radicals, but others influence the way cells receive, send and process signals that help them respond to their environment. Though most flavonoids aren’t well absorbed, the small amounts that do get into the blood stream and tissues seem to have potent effects.

Last month’s Staying Healthy issue featured a study linking dietary flavonoid intake and prostate health. This issue highlights new research1 that illustrates the diverse health-promoting potential of these nutrients.

Cocoa Flavonoids May Boost Mental Function

Prior studies have associated flavonoid intake with a decreased risk for dementia in older individuals. To investigate further, a team of Italian investigators enrolled 90 older individuals with mild cognitive impairment for an 8-week study. Participants were randomly assigned to consume a daily beverage containing low (45 mg), medium (520 mg) or high levels (990 mg) of cocoa flavanols (one class of flavonoids). The team assessed mental function using well-known cognitive tests.

People in both the medium and high level flavonoid groups were faster at completing tests which measure visual attention and mental flexibility, and also had significantly higher scores in verbal fluency. The verbal fluency test consists of giving people 60 seconds to list as many things as possible in a category, such as naming all the fruits and vegetables they can think of.

Improvements in blood pressure and the body’s sensitivity to insulin were also seen in those drinking the medium and high-level beverages. According to the researchers, the enhanced ability of insulin to process blood sugar had the greatest influence on the changes in cognitive function observed.

This study used special high-flavanol beverages, providing much higher flavanols than found in standard hot cocoa mixes on the market. Look for brands that are high in flavanols and low in sugar. Also tea, beans, apricots, berries, apples and some dark chocolate (in moderation) can contribute to overall flavanol intake.

Vitamin D and Diabetic Risk of Heart Disease

People with diabetes have a higher risk of heart disease that comes from developing clogged arteries, or atherosclerosis. The results of a small but intriguing study2 suggest that low levels of vitamin D could be one factor involved in the process of forming artery-blocking plague.

Researchers looked at vitamin D levels in people with and without diabetes who were similar in age, gender and weight. They found that diabetic patients with low vitamin D (defined as less than 30 ng/ml) had certain white blood cells that were more likely to stick to cells in the wall of blood vessels. When they adhere to vessel walls, these white blood cells (called macrophages) can fill up with cholesterol – an important step in the process of plaque formation.

The investigators point out that it’s not yet known whether improving blood levels of vitamin D can actually decrease the risk of developing atherosclerosis in diabetes. However, future trials are being planned that will test this idea.

References

1. Desideri G, et al. Benefits in cognitive function, blood pressure, and insulin resistance through cocoa flavanol consumption in elderly subjects with mild cognitive im-pairment: the Cocoa, Cognition, and Aging (CoCoA) study. Hypertension 60:794-801, 2012.
2. Riek AE, et al. Vitamin D suppression of endoplasmic reticulum stress promotes an antiatherogenic monocyte /macrophage phenotype in type 2 diabetic patients. J Biol Chem 287:38482-94, 2012.