Studies showing a positive association of high consumption of
processed and unprocessed red meat with the incidence of cardiovascular
disease
Several studies have demonstrated a positive association with high
consumption of unprocessed and processed red meat and the incidence of
CVD and cardiovascular (CV) mortality. These studies are listed in table
1 and they will be, briefly, discussed here. The study by Zheng et al
[6], is a prospective cohort study of 81,469 US men and women ages
59-61 years on the effects of high consumption of unprocessed and
processed red meat and incidence of CV mortality. After a mean follow-up
of 14.7 years, the highest consumption (> 05 servings/day)
of unprocessed red meat was associated with a 10% higher incidence of
CV mortality, HR 1.10 (95% CI 1.04- 1.17, p < 0.001)),
whereas the highest consumption of processed meat was associated with a
13% higher incidence of CV mortality, HR 1.13 (95% CI 1.04-1.23, p
< 0.001) compared to those with the lowest meat consumption.
In another prospective cohort study, Pan et al [21], analyzed the
effects of red meat consumption on all-cause mortality in 121,342 men
and women ages 52-54 free of CVD at baseline. After 22 years of
follow-up and multivariate adjustments, one serving of unprocessed or
processed red meat was associated with 13% and 20% increase in
all-cause mortality, HR 1.13 (95% CI 1.07-1.20), and 1.20 (95% CI
1.15-1.24), respectively. The corresponding percentages for CV mortality
were 18% and 21%, HR 1.18 (95% CI 1.13-1.23) and 1.21 (95% CI
1.13-1.31) for unprocessed and processed red meat, respectively. Also,
in a case-controlled study, Wang et al [22], examined the
relationship between unprocessed, processed, and total red meat
consumption with the incidence of CAD and fatal and nonfatal myocardial
infarction (MI) in 2,131 Costa Rican patients mean age 58.1 years. After
10 years of follow-up, the odds ratio (OR) for the onset of acute MI
were higher in the 5th quintile (11o.8 g/day) than the
1st quintile, OR 1,29 (95% CI 1.01-1.65) for
processed meat and OR 1.31 (95% CI 1.04-1.65) for total red meat
consumption, respectively. Regarding the influence of sex on the
incidence of MI, women had higher incidence than men, OR 1.47 (95% CI
0.80-2.69). In another prospective cohort study, Key et al [23],
examined the effects of meat on the incidence of ischemic heart disease
(IHD) in 409,885 subjects ages 51-61 years, from the Pan-European Epic
Cohort study. After 12.6 years of follow-up, the incidence of IHD
between the top 5th and bottom 5thof unprocessed or processed red meat consumption was increased by 10%
and 13 %, HR 1.10 (95% CI 0.99-1.21) and HR 1.13 (95% CI 1.02-1.26)
for unprocessed and processed red meat, respectively. In contrast, the
consumption of fish, poultry, milk, or eggs were not associated with an
increased incidence of IHD. Similarly, a prospective cohort study by
Alshahrami et al [24], examined the effects of unprocessed or
processed red meat on the incidence of CV mortality and all-cause
mortality in 96,000 subjects from the Seventh –day Adventist faith
53-57 years. After a mean follow-up of 11.8 years, unprocessed red meat
was associated with increased incidence of CV mortality and all-cause
mortality, HR 1.26 (95% CI 1.05-1.50) and HR 1.18 (95% CI 1.07-1.31),
respectively. Processed red meat alone was not associated with an
increased incidence of CV mortality, but the combination of unprocessed
and processed red meat was, HR 1.23 (95% CI 1.11-1.36). Also, a recent
study by Zhong et al [25], analyzed the of data from 6 US
prospective cohort studies of 29,682 subjects mean age 53.7 years, the
effects of red meat, poultry, or fish consumption on the incidence of
the composite endpoint of (CHD, stroke, HF, CVD, all-cause death). After
19 years of follow-up, there was a positive association of red meat
(processed and unprocessed), and poultry, but not fish on the incidence
of CVD and all-cause mortality. The adjusted HR (aHR) for CVD was 1.07
(95% CI1.04-1.11) for processed red meat, aHR 1.03 (95% CI 1.01-1.06)
for unprocessed red meat, and aHR 1.04 (95% CI 1.01-1.06) for poultry.
Also processed and unprocessed red meat had a positive association with
all-cause mortality, aHR 1.03 (95% CI 1.02-1.05), aHR 1.03 (95% CI
1.01-1.05), respectively. In contrast, poultry or fish consumption were
not associated with an increase in all-cause mortality.
Similar effects were demonstrated by several reviews and meta-analyses.
The review and meta-analysis by Micha et al [26], consists of 20
studies (17 prospective and 3 case control), involving 1,218,380
subjects on the effects of high meat consumption ( ≥ 100 g/day) on the
incidence of CHD. In this review, unprocessed red meat consumption was
not associated with an increased incidence of CHD, HR 1.00 (95% CI
0.81-1.23, p = 0.36) whereas, processed meat consumption was associated
with a 42% higher risk of CHD, HR 1.42 (95% CI 1.07-1.89, p = 0.04).
Associations were intermediate for total meat intake. In a review and
meta-analysis of prospective studies involving 1,330,352 subjects ages
20-86 years, Larsson et al [27], analyzed the effects of unprocessed
and processed red meat consumption on all-cause mortality. After a
follow-up of 9-28 years and multivariate adjustment analyses, the
highest vs the lowest consumption of unprocessed or processed red was
associated with 10%, HR 1.10 (95% CI 0.98-1.22) and 29%, HR 1.29
(95% CI 1.24-1.35) higher incidence of ACM, respectively. The study by
Bellavia et al [28], is a prospective study of 109,201 Swedish men
and women ages 45-79 years. After a mean follow-up of 15 years, those
subjects consuming > 100 g of unprocessed meat/day had a
shorter survival than those never consuming red meat. The HRs for total
red meat consumption were HR 1.16 (95% CI 1.06-1.127) for 150 g/day, HR
1.26 (95% CI 1.14-1.40) for 200 g/day, HR 1.37 (95% CI 1.21-1.36) for
250 g/day, and HR 1.49 (95% CI 1.27- 1.75) for 300 g/day, respectively.
This study demonstrated a dose-response association of total red meat
consumption with short term survival. The review and meta-analysis of 13
prospective cohort studies involving 1,674,272 subjects ages 18-92
years, by Abete et al [29], concerns the association of consumption
of unprocessed and processed red, white and total meat with mortality
from CVD, IHD, and all-cause mortality. The analysis of results from
these studies, showed that high consumption of unprocessed or processed
red meat was associated with an increased incidence of CVD mortality,
16% relative risk (RR), 1.16 (95% CI 1.03-1.32, p < 001) for
unprocessed red meat, and 18%, RR 1.18 (95% CI 1.05-1.32, p
< 0.002) for processed meat, respectively. Regarding the IHD
mortality, processed but not unprocessed red meat consumption, was
associated with a statistically increased IHD mortality, RR 1.52 (95%
CI 0.50-4,66, p = 0.004) for processed and RR 1.02 (95% CI 0.72-1.46)
for unprocessed red meat, respectively. Also, total red meat, but not
white meat consumption was associated with increased IHD mortality, RR
1.52 (95% CI 0.68-3.40) for total and RR 1.00 (95% CI 0.82-1.21) for
white meat, respectively. Regarding the consumption of processed meat,
this was associated with increased all-cause mortality, RR 1.22 (95% CI
1.16-1.29), but not the total red and white meat consumption. Also,
processed red meat was positively associated with increased all-cause
mortality in both men and women.