Help yourself to some nuts
this holiday season: Regular nut eaters were less likely to die of cancer or
heart disease – in fact, were less likely to die of any cause – during a
30-year Harvard study.
Nuts have long been called
heart-healthy, and the study is the largest ever done on whether eating them
Researchers tracked 119 000
men and women and found that those who ate nuts roughly every day were 20% less
likely to die during the study period than those who never ate nuts. Eating
nuts less often lowered the death risk too, in direct proportion to
The risk of dying of heart
disease dropped 29% and the risk of dying of cancer fell 11% among those who
had nuts seven or more times a week, compared with people who never ate them.
The benefits were seen from
peanuts as well as from pistachios, almonds, walnuts and other tree nuts. The
researchers did not look at how the nuts were prepared — oiled or salted, raw
Nut eaters slimmer
"There's a general
perception that if you eat more nuts you're going to get fat. Our results show
the opposite," said Dr. Ying Bao of Harvard-affiliated Brigham and Women's
Hospital in Boston.
She led the study,
published in the New England Journal of Medicine. The National
Institutes of Health and the International Tree Nut Council Nutrition Research
& Education Foundation sponsored the study, but the nut group had no role
in designing it or reporting the results.
Researchers don't know why
nuts may boost health. It could be that their unsaturated fatty acids, minerals
and other nutrients lower cholesterol and inflammation and reduce other
problems, as earlier studies seemed to show.
Observational studies like
this one can't prove cause and effect, only suggest a connection. Research on
diets is especially tough, because it can be difficult to single out the
effects of any one food.
Avoiding unhealthy food
People who eat more nuts
may eat them on salads, for example, and some of the benefit may come from the
leafy greens, said Dr. Robert Eckel, a University of Colorado cardiologist and
former president of the American Heart Association.
Dr Ralph Sacco, a
University of Miami neurologist who also is a former heart association
"Sometimes when you
eat nuts you eat less of something else like potato chips," so the benefit
may come from avoiding an unhealthy food, Sacco said.
The Harvard group has long
been known for solid science on diets. Its findings build on a major study
earlier this year – a rigorous experiment that found a Mediterranean-style diet
supplemented with nuts cuts the chance of heart-related problems, especially
strokes, in older people at high risk of them.
Dense in calories
Many previous studies tie
nut consumption to lower risks of heart disease, diabetes, colon cancer and
In 2003, the Food and Drug
Administration said a fistful of nuts a day as part of a low-fat diet may
reduce the risk of heart disease. The heart association recommends four
servings of unsalted, un-oiled nuts a week and warns against eating too many,
since they are dense in calories.
The new research combines
two studies that started in the 1980s on 76 464 female nurses and 42 498 male
health professionals. They filled out surveys on food and lifestyle habits
every two to four years, including how often they ate a serving (1 ounce) of
Study participants who
often ate nuts were healthier — they weighed less, exercised more and were less
likely to smoke, among other things. After taking these and other things into
account, researchers still saw a strong benefit from nuts.
Compared with people who
never ate nuts, those who had them less than once a week reduced their risk of
death 7%; once a week, 11%; two to four times a week, 13%; and seven or more
times a week, 20%.
confident" the observations reflect a true benefit, Bao said. "We did
so many analyses, very sophisticated ones," to eliminate other possible
For example, they did
separate analyses on smokers and non-smokers, heavy and light exercisers, and
people with and without diabetes, and saw a consistent benefit from nuts.
At a heart association
conference in Dallas this week, Penny Kris-Etheron, a Pennsylvania State
University nutrition scientist, reviewed previous studies on this topic.
"We're seeing benefits
of nut consumption on cardiovascular disease as well as body weight and
diabetes," said Kris-Etherton, who has consulted for nut makers and also
served on many scientific panels on dietary guidelines.
"We don't know exactly
what it is about nuts that boosts health or which ones are best," she
said. "I tell people to eat mixed nuts."