Eating nuts linked to longer life and lower risk of diseases
21 November 2013
A study tracking the diet of over 100,000 men and women over 30
years has found that people who ate a daily handful of nuts were 20%
percent less likely to die from any cause than were those who didn’t
consume nuts. In addition, the nut eaters were slimmer than those
who didn't eat nuts.
The study by the Dana-Farber Cancer Institute, Brigham and
Women’s Hospital, and the Harvard School of Public Health has been
published in the New England Journal of Medicine, contains
further good news.
The reduction in mortality was similar both for peanuts and for
'tree nuts' — walnuts, hazelnuts, almonds, Brazil nuts, cashews,
macadamias, pecans, cashews, pistachios and pine nuts.
Data analysis methods were used to rule out other dietary and
lifestyle factors that might have accounted for the mortality
benefits. For example, the researchers found that individuals who
ate more nuts were leaner, less likely to smoke, and more likely to
exercise, use multivitamin supplements, consume more fruits and
vegetables, and drink more alcohol. However, the analysis was able
to isolate the association between nuts and mortality independently
of these other factors.
Several previous studies have found an association between
increasing nut consumption and a lower risk of diseases such as
heart disease, type 2 diabetes, colon cancer, gallstones, and
diverticulitis. Higher nut consumption also has been linked to
reductions in cholesterol levels, oxidative stress, inflammation,
adiposity, and insulin resistance.
Some small studies have linked increased nuts in the diet to
lower total mortality in specific populations. But no previous
research studies had looked in such detail at various levels of nut
consumption and their effects on overall mortality in a large
population that was followed for over 30 years.
“The most obvious benefit was a reduction of 29% in deaths from
heart disease — the major killer of people in America,” said Charles
S. Fuchs, MD, MPH, director of the Gastrointestinal Cancer Center at
Dana-Farber, who is the senior author of the report. “But we also
saw a significant reduction — 11% — in the risk of dying from
cancer,” added Fuchs, who is also affiliated with the Channing
Division of Network Medicine at Brigham and Women’s.
“In all these analyses, the more nuts people ate, the less likely
they were to die over the 30-year follow-up period,” explained Ying
Bao, MD, ScD, of Brigham and Women’s Hospital, first author of the
report. Those who ate nuts less than once a week had a 7% reduction
in mortality; once a week, 11% reduction; two to four times per
week, 13% reduction; five to six times per week, 15% reduction, and
seven or more times a week, a 20% reduction in death rate.
The authors do note that this large study cannot definitively
prove cause and effect; nonetheless, the findings are strongly
consistent with “a wealth of existing observational and clinical
trial data to support health benefits of nut consumption on many
chronic diseases.” In fact, based on previous studies, the US Food
and Drug Administration concluded in 2003 that eating 1.5 ounces per
day of most nuts “may reduce the risk of heart disease.”
The study used databases from two well-known ongoing
observational studies that collect data on diet and other lifestyle
factors and various health outcomes. The Nurses’ Health Study
provided data on 76,464 women between 1980 and 2010, and the Health
Professionals’ Follow-up Study yielded data on 42,498 men from 1986
Participants in the studies filled out detailed food
questionnaires every two to four years. With each food
questionnaire, participants were asked to estimate how often they
consumed nuts in a serving size of one ounce.