Diets that replaced red meat with healthy plant proteins led to
decreases in risk factors for cardiovascular disease (CVD),
according to a new study from Harvard TH Chan School of Public
Health and Purdue University.
The study is the first meta-analysis of randomized controlled
trials examining the health effects of red meat by substituting it
for other specific types of foods.
It was published recently in the journal Circulation.
"Previous findings from randomized controlled trials evaluating
the effects of red meat on cardiovascular disease risk factors have
been inconsistent," said Marta Guasch-Ferré, research scientist in
the Department of Nutrition and lead author of the study.
"But our new study, which makes specific comparisons between
diets high in red meat versus diets high in other types of foods,
shows that substituting red meat with high-quality protein sources
lead to more favourable changes in cardiovascular risk
The study included data from 36 randomized controlled trials
involving 1,803 participants.
The researchers compared people who ate diets with red meat with
people who ate more of other types of foods (ie, chicken, fish,
carbohydrates, or plant proteins such as legumes, soy, or nuts),
looking at blood concentrations of cholesterol, triglycerides,
lipoproteins, and blood pressure-all risk factors for CVD.
The study found that when diets with red meat were compared with
all other types of diets combined, there were no significant
differences in total cholesterol, lipoproteins, or blood pressure,
although diets higher in red meat did lead to higher triglyceride
concentrations than the comparison diets.
However, researchers found that diets higher in high-quality
plant protein sources such as legumes, soy, and nuts resulted in
lower levels of both total and LDL ("bad") cholesterol compared to
diets with red meat.
The results are consistent with long-term epidemiologic studies
showing lower risks of heart attacks when nuts and other plant sources of protein are compared to red
The findings also suggest that the inconsistencies found in
prior studies regarding the effects of red meat on cardiovascular
risk factors may be due, in part, to the composition of the
They recommended that future studies take specific comparisons
"Asking 'Is red meat good or bad?' is useless," said Meir
Stampfer, professor of epidemiology and nutrition and also an
author of the study.
"It has to be 'Compared to what?' If you replace burgers with
cookies or fries, you don't get healthier. But if you replace red
meat with healthy plant protein sources, like nuts and beans, you
get a health benefit."
The authors recommended adherence to healthy vegetarian and
Mediterranean-style diets, both for their health benefits and to
promote environmental sustainability.