Study shows a benefit, but that tapers off after 5 servings per day
By Dennis Thompson
TUESDAY, July 29, 2014 (HealthDay News) -- The nutrients in fruits and vegetables are vital to good health and a long life, but only up to a point. Once you've hit five servings of fruits and vegetables each day, additional daily servings don't appear to boost longevity, a new research review suggests.
The human body may only be able to effectively process a certain amount of fruits and vegetables every day, limiting its ability to absorb important nutrients from extra helpings, said the review's senior author Dr. Frank Hu, a professor of nutrition and epidemiology at the Harvard School of Public Health in Boston.
"It is possible that the digestibility of fruits and vegetables and the availability of nutrients and other bioactive compounds of these foods may have reached a plateau at five servings per day for most people," Hu said. "More research is clearly needed in this area."
Before you reach that five servings a day recommendation, however, the review suggests that the risk of death from any cause drops 5 percent for each additional daily serving of fruits or vegetables consumed. And, the risk of death from heart disease seems to decrease 4 percent for each additional daily serving of fruits and vegetables, according to Hu's research.
However, the study is only designed to show an association between fruit and vegetable consumption and the risk of death during the study periods. It isn't able to prove that eating fruits and vegetables is the cause of the reduced risk.
Still, the research supports dietary guidelines that recommend five servings of fruit and vegetables a day, said Joy Dubost, a registered dietitian in the Washington, D.C., area and a spokeswoman for the Academy of Nutrition and Dietetics.
Dubost said it's pointless to worry about an upper limit at which people gain little or no benefit from fruits or vegetables, given that it's so hard to get people to eat their veggies anyway.
She noted that adults eating an average 2,000-calorie daily diet should eat 2.5 cups of vegetables every day, but instead eat an average 1.6 cups. The same goes for fruit -- adults should eat 2 cups a day, but on average can manage only 1 cup.