According to new research published today in the American Heart Association's flagship journal Circulation, consuming about five daily servings of fruits and vegetables, with two servings of fruits and three servings of vegetables, is possibly the optimum amount for longer life.
Fruit and vegetable-rich diets tend to lower the risk of a variety of chronic health problems, such as cardiovascular disease and cancer, which are leading causes of death. According to the US Centers for Disease Control and Prevention, only about one out of every ten adults consumes enough fruits and vegetables.
"While organizations such as the American Heart Association recommend four to five servings of fruits and vegetables a day, consumers are likely to receive mixed messages on what constitutes optimal daily intake of fruits and vegetables, such as the recommended amount and which foods to include and avoid," said lead study author Dong D. Wang, M.D., Sc.D., an epidemiologist, nutritionist, and member of the American Heart Association.
Wang and colleagues looked at information from the Nurses' Health Study and the Health Professionals Follow-Up Study, two surveys that included over 100,000 people who were monitored for up to 30 years. Both databases contained comprehensive dietary data that were obtained every two to four years on a regular basis. Researchers combined data on fruit and vegetable consumption and death from 26 studies involving nearly 1.9 million people from 29 countries and territories in North and South America, Europe, Asia, Africa, and Australia for this study.
The results of an analysis of all studies with a total of more than 2 million participants showed the following:
1. The lowest risk of death was associated with a daily intake of around five servings of fruits and vegetables. More than five servings were not linked to any added benefits.
2. The most longevity was linked to eating about two servings of fruits and three servings of vegetables a day.
3. Participants who consumed five servings of fruits and vegetables a day had a 13 percent lower risk of death from all causes, a 12 percent lower risk of death from cardiovascular disease, including heart disease and stroke, a 10% lower risk of death from cancer, and a 35 percent lower risk of death from respiratory disease as compared to those who consumed two servings per day (COPD).
4. Not all foods classified as fruits and vegetables had the same health benefits. Starchy vegetables like peas and corn, fruit juices, and potatoes, for example, were not linked to a lower risk of death from any cause or from serious chronic diseases.
5. Green leafy vegetables, such as spinach, lettuce, and kale, as well as fruit and vegetables high in beta carotene and vitamin C, such as citrus fruits, berries, and carrots, were found to have health benefits.
"Our findings in the two cohorts of U.S. men and women were identical to those in 26 cohorts around the world, indicating that our findings are biologically plausible and that they can be generalized to larger populations," Wang said.
This research, according to Wang, determines an optimum fruit and vegetable intake level and supports the evidence-based, concise public health message of '5-a-day,' which states that people should preferably eat five servings of fruit and vegetables each day. "This volume likely provides the greatest advantage in terms of chronic disease prevention and is a reasonably realistic intake for the general public," he said. "We have discovered that not all fruits and vegetables have the same level of value, despite the fact that existing dietary guidelines consider all fruits and vegetables equally, including starchy vegetables, fruit juices, and potatoes."
The study's main drawback is that it is observational, demonstrating a connection between fruit and vegetable consumption and the risk of death but not a clear cause-and-effect relationship.
"At least half the plate should be filled with fruits and vegetables at each meal," according to Anne Thorndike, M.D., M.P.H., chair of the American Heart Association's nutrition committee and associate professor of medicine at Harvard Medical School in Boston. "This study offers solid evidence for the long-term effects of consuming fruits and vegetables, as well as a daily target number for optimal health. Fruits and vegetables are naturally packaged sources of nutrients that can be incorporated into a variety of meals and snacks, and they are critical for maintaining the health of our hearts and bodies."
The National Institutes of Health, the American Heart Association, and the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health all contributed to the research.
Source: Healthy Food. Happy Hearts.