Study: More fruit, veggies bring smiles
Updated: Thursday, November 29, 2012 11:50 AM
Seven 3-ounce portions linked to positive well-being
By STEVE BROWN
British researchers have found that eating plenty of fruits and vegetables not only improves your physical health, it helps your emotional well-being, too.
Andrew Oswald, professor of economics at the University of Warwick in Coventry, England, said little research had been done previously on food's effect on emotional well-being.
"Public health literature examines how it benefits the health of the body," he said. "This study has shown surprising results, and I have decided it is prudent to eat more fruit and vegetables. I am keen to stay cheery."
Many Western governments recommend five servings of fruit and vegetables a day for cardiovascular health and as protection against cancer risk. The report found that happiness and mental health are highest among people who eat seven 3-ounce portions of fruit and vegetables a day.
Oswald, along with fellow Warwick professor Sarah Stewart-Brown and David Blanchflower, professor of economics at Dartmouth College in Hanover, N.H., presented the findings in a paper written for the National Bureau of Economic Research.
What the team found was that eating more than the usual recommendations of fruits and vegetables leads to measurably improved mental health.
"The statistical power of fruit and vegetables was a surprise. Diet has traditionally been ignored by well-being researchers," Stewart-Brown said.
The study did not distinguish among different kinds of fruits and vegetables, nor did it matter whether the fruits and vegetables were fresh, frozen or canned.
"But most doctors would like us to eat a lot of fresh products because they retain antioxidant qualities," Oswald said.
The survey also did not consider organically grown produce versus conventionally grown.
One of the surveys found that individuals consuming eight or more servings of fruits and vegetables per day have a life-satisfaction score 0.27 points higher than those who eat almost no fruits and vegetables.
To put that into perspective, the increment of being a nonsmoker is 0.19. The increment of being married is 0.36. The effect of being unemployed is a negative 0.90 points.
In some of the studies, the benefits leveled off at or above five servings a day. In others, they continued to increase up to seven or eight portions a day.
Surveys found the intake of meat, fish and alcohol didn't impact the results. They also took into account other well-being variables like body mass index, race, marital status, long-standing illness, religious practice and sexual activity.
Researchers found that levels of meat and fish consumption make little difference in the equation, except that eating no fish whatsoever is associated with worse mental well-being.
In considering consumption of alcohol, they wrote: "Those who drink one or two days a week have the lowest level of GHQ (General Health Questionnaire) psychological disorders. There is no statistically significant difference between the GHQ score of a non-drinker and someone who drinks alcohol almost every day."
The researchers said that thinking about the types of foods people consume "appears to be a potentially valuable one for social scientists and perhaps also eventually for governments concerned with the ultimate happiness of their citizens."
How psychological health is measured
One measure of psychological health, the Warwick-Edinburgh Mental Well-being Scale, is based on the range of responses to statements like:
* I've been feeling optimistic over the past two weeks.
* I've been feeling useful.
* I've been feeling relaxed.
* I've been feeling interested in other people.
* I've had energy to spare.
* I've been dealing with problems well.
* I've been thinking clearly.
* I've been feeling confident.
* I've been feeling loved.