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xperts
know that processed red meats are likely to raise the risk of cardiovascular
disease and death. But are unprocessed meats, fish, and poultry less harmful?
New research investigates.
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PinterestNew research evaluates the impact of different kinds of meat, poultry,
and fish on cardiovascular and all-mortality risk.
Several studies have
established a link between consuming processed meat — such as bacon, hot dogs,
sausages, and other similar meats — and an increased risk of cardiovascular
disease (CVD) and death.
The higher amount of saturated
fats in these foods, along with a higher level of salt and preservatives, might
explain these associations. Newer research has
suggested that even a low amount of these foods is enough to jeopardize health.
But what about other meats, such
as unprocessed red meat, poultry, or fish? Do these foods affect cardiovascular
risk and longevity in the same way?
Here, the research is more mixed.
The results of several studies vary partly because the methods were different
and partly because the existing prospective cohort studies had their limitations.
So, to fill this gap in the
research, a group of scientists led by Victor W. Zhong, Ph.D., of Cornell
University in Ithaca, New York, set out to conduct a new meta-analysis of 6
existing studies.
The pooled analysis appears in
the journal JAMA Internal Medicine.
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Zhong and the team looked at
prospective cohort studies that had been carried out across the United States,
totaling 29,682 U.S. adults who did not have CVD at baseline.
Of the participants, 44% were
men, and almost 31% were non-white.
Researchers had recorded the
participants’ dietary data between 1985–2002 and clinically followed them for
30 years, until August 31, 2016.
Over a median follow-up period of
19 years, 6,963 adverse cardiovascular events and 8,875 all-cause deaths
occurred.
Of the cardiovascular events,
38.6% were cases of coronary heart disease, 25% were stroke events, and 34.0%
involved heart failure.
To define what constitutes 1
serving of meat and assess the participants’ diet, the researchers used the
Willett Food Frequency Questionnaire.
“1
serving was equivalent to 4 [ounces] of unprocessed red meat or poultry or 3
[ounces] of fish. For processed meat, 1 serving consisted of 2 slices of bacon,
2 small links of sausage, or 1 hot dog,” explain the authors.
The median consumption in terms
of servings of meat, poultry, and fish per week was 1.5 for processed meat, 3
for unprocessed red meat, 2 for poultry, and 1.6 for fish.
“Compared with participants with
lower total intake of these four food types, participants with higher total
intake,” write the authors, were more likely to:
- be
younger and male
- be
non-Hispanic black
- be
smokers, have diabetes, a higher body mass index (BMI), higher
non-high-density lipoprotein (HDL) cholesterol levels, and consume more
alcohol
- have
lower HDL cholesterol levels and eat a lower diet quality diet
- have
a higher incidence of CVD and death from any cause
The main outcome that the
scientists looked for was the relative risk of CVD and all-cause mortality over
the 30 years between people who consumed these different foods, as well as the
difference in absolute risk over the same period.
They calculated the risks for
each additional intake of 2 servings per week.
Zhong and the team summarize the
findings: the “intake of processed meat, unprocessed red meat, or poultry was
significantly associated with incident cardiovascular disease, but fish intake
was not.”
More
specifically, the increased relative risks of CVD and all-cause mortality
ranged from about 3% to 7%. “The increased absolute risks were less than 2%
over the 30 years of follow-up,” add the authors.
More in-depth detail shows that
for every 2 additional servings of processed meat per week, the relative risk
of all-cause mortality rose by 3% compared with those who did not eat processed
meat.
The same was true for each
additional 2 servings of unprocessed meat.
The relative risk of CVD rose by
7% for every 2 servings of processed meat per week. For unprocessed red meat,
this risk was 3%.
An increase of 2 weekly servings
of poultry correlated with a 4% higher relative risk, whereas fish was not
associated with CVD risk.
“People who consume more servings
per week would have greater risks,” add the researchers.
The authors deem the findings of
“critical public health” importance. They also note that more research is
necessary to strengthen the findings.
As it stands, the current study
has some limitations, such as the self-reported nature of dietary data. This
may have resulted in over or underestimation of the association.
Secondly, the scientists did not
have any data on the method of food preparation. Whether the meat was fried or
non-fried may have impacted the health outcomes.
Thirdly, the study only used one
dietary measurement at the beginning of the study, but the dietary habits of
the participants may have changed over time.
Finally, residual confounding,
the observational nature of the study, and the fact that the data may only be
limited to U.S. adults are further shortcomings of this research. Still, Zhong
and team conclude:
“The findings of this study appear to have critical
public health implications given that dietary behaviors are modifiable, and
most people consume these four food types on a daily or weekly basis.”
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