When in doubt, go for the greens. An article in the August 29 issue of Circulation adds to the body of evidence that demonstrates that a folate-rich diet that includes foods like dark green leafy vegetables can reduce blood levels of homocysteine--a step that may benefit heart health.

Homocysteine is an amino acid produced by the body as a by-product of metabolism. High blood levels of homocysteine have been linked to an increased risk of heart disease. Scientists think that certain nutrients--folate, and vitamins B12 and B6--may have a moderating effect on homocysteine, helping to lower harmfully high levels, thereby reducing the risk of heart disease.

This latest analysis is an extension of an earlier project called the Dietary Approaches to Stop Hypertension (DASH) Study that looked at how different foods appear to affect blood pressure. Researchers divided study participants into three groups: one consumed a "typical" American diet. A second group consumed a diet high in fruits and vegetables. The third ate a "combination" diet high in fruits, vegetables, and low-fat dairy foods and low in total fat and saturated fat. Called a "combination diet" because it incorporated several kinds of foods thought to affect blood pressure, it is currently referred to as the DASH diet. The researchers tested the participants' blood levels of homocysteine, as well as folate, B12, and B6 at the start and end of the eight-week study.

Results show that participants who followed the combination diet had notably lower levels of homocysteine than those who followed the other two diets. Further, the association between diet and lowered homocysteine levels appeared to be tied to folate intake. In other words, the average reduction in homocysteine levels seen during the study corresponded to an average rise in blood folate levels.

Even with this new information, though, some parts of the diet and homocysteine connection are still unclear. Scientists know that people who have heart disease often have high blood levels of homocysteine, but it is not yet clear if high homocysteine is a cause or an effect of heart disease. The authors of the study also point out that the DASH study was designed to assess the potential health benefits of a whole diet, not individual nutrients. They say that a meal plan such as the DASH diet may include nutrients in addition to folate that can affect homocysteine levels.

On the plus side, the diet is a low-fat, high-fiber, nutrient-rich meal plan that helped lower blood pressure in DASH study participants. Choosing such a diet of fruits and vegetables, whole grain foods, lean meats, and low-fat dairy foods is a smart way for individuals to provide themselves a buffer against many kinds of chronic diseases, including heart disease.