Some Peanuts a Day Keep Cancer, CVD Away
Eating more nuts correlated with significantly lower mortality, both
overall and for cancer, heart disease, and lung disease, according to
data from follow-up in two large cohort studies.
As the frequency
of nut consumption increased, the mortality hazard decreased by 7% with
weekly intake to 20% for daily nut consumption, as compared with people
who did not eat nuts.
The benefits pertained to any type of nut consumption, not specific nuts,
Charles S. Fuchs, MD, of Dana-Farber Cancer Institute in Boston, and co-authors reported online in the
New England Journal of Medicine.
"We
did look at subtypes of nuts, but I can tell you that we really don't
see a difference between the various nut types," Fuchs told
MedPage Today. "So, peanuts as opposed to other nuts seemed to confer the same benefit in reducing mortality."
Nuts
have a high nutrient density and a high concentration of unsaturated
fatty acids. Observational studies have linked nut consumption to
beneficial effects related to coronary heart disease and certain heart
disease risk factors.
As a result of the evidence, the FDA in 2003 recommended consumption of
1.5 ounces of nuts daily as part of a low-fat diet that "may reduce the risk of heart disease."
More recently, a randomized trial of primary prevention in patients with a high cardiovascular risk showed that a
nut-containing Mediterranean diet was associated with a significantly lower risk of cardiovascular events, as compared with patients assigned to a control diet.
Multiple
observational and interventional studies have demonstrated favorable
effects of nut consumption on various diseases (diabetes, colon cancer,
gallstones) and in recognized mediators of chronic disease (oxidative
stress, inflammation).
The accumulation of data has included
minimal evidence that nut consumption reduces total mortality, the
authors noted in their introduction. Additionally, the studies have been
limited by small sample size, limited dietary information, and lack of
adequate adjustment for confounders.
To examine the relationship
of nut consumption to mortality, investigators analyzed data from 76,464
women who participated in the
Nurses' Health Study and from 42,498 men in the
Health Professionals Follow-up Study. Both studies accumulated data from multiple follow-up visits and questionnaires over 20 to 24 years.
The
final analysis comprised 3,038,853 person-years of follow-up, during
which time 16,200 women and 11,229 men died. Comparison of the two
studies showed no significant heterogeneity, so investigators combined
the results into a single analysis.
As compared with study participants who reported no consumption, the mortality hazard declined significantly (
P<0.001 for trend) as weekly nut consumption increased:
- Less than once -- HR 0.93, 95% CI 0.90-0.93
- Once -- HR 0.89, 95% CI 0.86-0.93
- Two to four times -- HR 0.87, 95% CI 0.83-0.90
- Five or six times -- HR 0.85, 95% CI 0.79-0.91
- Seven or more -- HR 0.80, 95% CI 0.73-0.86
The mortality benefit with increasing nut consumption ranged from 6% to 21% in women (
P<0.001) and from 9% to 20% in men (
P<0.001).
Among both sexes, each category of nut consumption had a significantly
lower mortality hazard as compared with people who reported no
consumption.
Subgroup analysis showed no difference in benefit
among peanuts, tree nuts, and other types of nuts with respect to
all-cause mortality or death from heart or respiratory disease or
cancer.
Commenting on possible concerns about the fat and calories
in nuts, Fuchs said the evidence still supports regular nut
consumption.
"We really don't see a problem with it," he said. "In
fact, one might argue that nuts are probably a very good source of
calories, namely, calories that don't seem to contribute to obesity."