Archive

Health Bits and Pieces
By Michael Janson, M.D.
October 10, 2007

Supplements of omega-3 essential fatty acids from fish lower blood pressure according to many studies. New research shows that consuming omega-3 oils from plant food sources, such as soybean oil, flaxseeds, and walnuts, has the same effect. (Ueshima H, et al., “Food Omega-3 Fatty Acid Intake of Individuals (Total, Linolenic Acid, Long-Chain) and Their Blood Pressure, INTERMAP Study,” Hypertension, 2007 Jun 4; [Epub ahead of print].) Plant sources of omega-3 oils contain alpha-linolenic acid (ALA), the precursor to EPA and DHA that are manufactured by the body. The study of 4680 subjects aged 40 to 59 showed modest decreases in both systolic and diastolic blood pressures with increasing consumption of ALA-containing foods.

Another study of Age Related Macular Degeneration (ARMD) showed that Vitamin D intake also plays a role in protection from that disease. In this research on 7752 subjects, the risk of developing the early stages of ARMD was reduced by 36 percent in those with the highest intake of Vitamin D compared to those with the lowest intake. (Parekh N, et al., “Association between vitamin D and age-related macular degeneration in the Third National Health and Nutrition Examination Survey, 1988 through 1994,” Arch Ophthalmol, 2007 May;125(5):661-9.) The association was greatest for Vitamin-D intake from fish and supplements, while milk was in the middle. Of course, Vitamin D is present in milk because it is added as a supplement, so the relationship is not directly with milk but with fish and supplemental sources. Vitamin D has anti-inflammatory effects and also inhibits excessive new vessel formation in the retina, both of which effects might contribute to its benefits in macular degeneration.

Flavonoids (or bioflavonoids) are plant-derived chemicals (phytochemicals) with important nutritional value, even though they are not essential to metabolism. A wide variety of flavonoids is found in fruits, vegetables, whole grains, and legumes.

New research shows that a high intake of flavonoids is associated with better brain function and a slower rate of cognitive decline with aging. A study in France of 1640 subjects over 65 years old showed that those with the highest flavonoid intake at the start of the study performed better on tests of mental function than those with the lowest intake. In addition, over the 10 years of the study, the functional decline of mental ability was significantly less in those with the highest intake.

The better brain function was not related specifically to fruits and vegetables or to red wine and tea, all sources of flavonoids, but to the overall flavonoid content of the diet. (Letenneur L, et al., “Flavonoid intake and cognitive decline over a 10-year period,” Am J Epidemiol, 2007 Jun 15;165(12):1364-71.) One improvement was in the Mini-Mental State examination, which showed twice as much decline in the group with the lowest flavonoid intake than in the group with the highest intake.

Although the subjects in this study did not take dietary supplements in significant quantities, many flavonoids are available as supplements. However, because of the wide variety of nutrients in fruits, vegetables, whole grains, and legumes, it is wise to consume these in large amounts in addition to any supplementation.

A new study confirms the value of the Mediterranean diet for protection from heart disease and diabetes. The diet is rich in vegetables and fruits, nuts, fish, olive oil, and legumes, while it contains much less animal-derived food than the typical Western diet. The Australian study of 40,653 participants, 40 to 69 years old, showed that those who ate most closely to the Mediterranean diet pattern had a 30- to 40-percent lower risk of dying of cardiovascular disease than those who strayed furthest from that diet. Among diabetics, there was a trend to have less vascular disease. This diet pattern was helpful even if people already had heart disease at the start of the study, and the results were apparent even among those who had other high risk factors for heart disease, such as increased body mass index and hypertension. (Harriss LR, et al., “Dietary patterns and cardiovascular mortality in the Melbourne Collaborative Cohort Study,” Am J Clin Nutr. 2007 Jul;86(1):221-9.)

A study of patients with hypertension showed benefits from supplementation with a combination of alpha lipoic acid and acetyl-L-carnitine. In 36 subjects with coronary artery disease, half were given the active treatment and half a placebo for eight weeks. (McMackin CJ, et al., “Effect of combined treatment with alpha-Lipoic acid and acetyl-L-carnitine on vascular function and blood pressure in patients with coronary artery disease,” J Clin Hypertens (Greenwich). 2007 Apr;9(4):249-55.) In the patients with the highest blood pressures, the combined supplements significantly lowered blood pressure by about 10 points. It also improved vascular function by relaxing the blood vessels.

Silymarin is a standardized extract of milk thistle with a number of antioxidant and anti-inflammatory effects. It has long been used to help support the liver. A laboratory study of silymarin showed that it has benefits as both a prophylactic and a treatment for hepatitis C virus. It also had specific antiviral effects. (Polyak SJ, et al., “Inhibition of T-cell inflammatory cytokines, hepatocyte NF-kappaB signaling, and HCV infection by standardized Silymarin,” Gastroenterology. 2007 May;132(5):1925-36.) One of the observed effects was stimulation of white blood cells, enhancing their ability to fight infection. Other research has shown anti-cancer effects in both skin and prostate by a number of cellular mechanisms. In prostate cells, silymarin inhibits androgen receptors and induces cell-cycle arrest, and in animal studies it retards the growth of advanced prostate cancer. (Deep G, Agarwal R, Chemopreventive efficacy of silymarin in skin and prostate cancer. Integr Cancer Ther. 2007 Jun;6(2):130-45.) September, 2007©