Strawberries could lower cardiovascular disease risk factors

14/04/05 Eating a serving of California strawberries daily for eight weeks significantly lowers one of the risk factors for cardiovascular disease, according to a study released at Experimental Biology, a meeting of leading life scientists. In the study, plasma homocysteine (HCY) levels decreased in subjects whose HCY levels were borderline-high at baseline.

The study, led by Gene Spiller, PhD, of the Sphera Foundation and the Health Research and Studies Center in Los Altos, Calif., measured plasma HCY levels in 24 healthy volunteers before and after they went on a special diet that included a daily serving of strawberries, but was otherwise low in fruits, vegetables and whole grains and was devoid of any other berries.

All subjects spent an initial four weeks eating their usual diets but no berries of any kind. This was a “washout” phase, supervised by a nutritionist, so they would enter the study without any residual stores of any of the nutrients in strawberries that might decrease HCY.   At the end of this four-week period their plasma HCY levels were measured.  Of the 24, ten had HCY levels greater than 9 micromoles per liter. 

For the next eight weeks they ate a daily serving of strawberries, but no other berries, and few other fruits and vegetables.  After two months, it was found that plasma HCY levels declined significantly in the ten subjects whose HCY was borderline-high (greater than 9.0 ìmol/L) at baseline, but not in those who had lower HCY at the start. 

According to the American Heart Association, it is not yet known whether lowering plasma HCY will actually cut the risk of heart disease, despite a great deal of evidence that elevated HCY increases risk. Conversely, plasma HCY levels below 9.0 ìmol/L have been associated with a greatly reduced risk of cardiovascular disease.  For example, in one prospective study, people with HCY over 15.0 ìmol/L had a risk of heart disease about six times higher than people with HCY under 9.0 ìmol/L.  One expert has calculated that levels of HCY over 15.0 ìmol/L, compared to under 10.0 ìmol/L, would be equivalent to the risk of serum cholesterol at 275 mg/dL versus 189 mg/dL.  It is generally accepted that levels of HCY over 10.0 ìmol/L are undesirable.

Strawberries are rich in a number of nutrients that may play important roles in disease prevention, including vitamin C, folate, potassium, and flavonoids such as anthocyanins, the natural pigments responsible for the red color of strawberries.  While folate and other B vitamins have been most associated with HCY-lowering, some data suggest that antioxidants such as vitamin C and flavonoids may also contribute. 

From the new study, Dr. Spiller concludes, “Consumption of strawberries appears to be a desirable addition to a diet that helps control plasma HCY and reduce the risk of heart disease.” 

The study was funded by a grant from the California Strawberry Commission, an association that represents more than 600 strawberry growers, shippers and processors and conducts programs in product and production research, public policy and public relations.