By Seema Gupta, MD, MSPH

Clinical Assistant Professor, Department of Family and Community Health, Joan C. Edwards School of Medicine, Marshall University, Huntington, WV

Dr. Gupta reports no financial relationships relevant to this field of study.

SYNOPSIS: Investigators found consuming more processed meat, unprocessed red meat, or poultry (but not fish) was closely connected to a higher risk for incident cardiovascular disease. Meanwhile, consuming processed meat or unprocessed red meat (but neither fish nor poultry) was strongly associated with a higher risk of all-cause mortality.

SOURCE: Zhong VW, Van Horn L, Greenland P, et al. Associations of processed meat, unprocessed red meat, poultry, or fish intake with incident cardiovascular disease and all-cause mortality. JAMA Intern Med 2020; Feb 3. doi: 10.1001/jamainternmed.2019.6969. [Epub ahead of print].

In the diet of U.S. adults, meat is a major source of protein and fat as well as minerals such as iron, zinc, and several vitamins (including B). The meat and poultry industry is the largest segment of U.S. agriculture, and Americans eat more meat annually than any other nation.1

Red meat often is processed to allow an improvement in shelf life as well as color and taste. Meat may be cured, salted, or smoked (e.g., ham or bacon). These processes add high amounts of ingredients known to be unhealthy, including salts, saturated fats, polycyclic aromatic hydrocarbons, and cholesterol. Therefore, eating too much processed meat could lead to an increased intake of these ingredients. Growing evidence reveals eating more red meat may lead to premature death, including death from cardiovascular disease (CVD) and cancer, but the results are not consistent.2,3 The authors of several of these studies argued that plausible mechanisms for poor outcomes are available linking processed meat consumption and risk of chronic diseases, such as stroke, heart failure, CVD, diabetes mellitus, and cancer, at several sites, as well as mortality.4 However, associations of poultry, fish, or unprocessed red meat consumption with CVD and mortality remain uncertain.

In their cohort study, Zhong et al analyzed individual-level data for approximately 30,000 U.S. adults from six prospective cohort studies. These included the Cardiovascular Health Study (CHS), the Atherosclerosis Risk in Communities (ARIC) study, the Framingham Heart Study (FHS), the Coronary Artery Risk Development in Young Adults (CARDIA) study, the Multi-Ethnic Study of Atherosclerosis (MESA), and Framingham Offspring Study (FOS).

The authors collected baseline diet data from 1985 to 2002. Study participants were followed up until mid-2016. The mean age of participants was 53.7 years, about 55% were women, and 69% of the total participants were non-Hispanic white (23% were non-Hispanic black). The researchers found that regular consumption of processed red meat (adjusted hazard ratio [HR], 1.07; 95% confidence interval [CI], 1.04 to 1.11), unprocessed red meat (adjusted HR, 1.03; 95% CI, 1.01 to 1.06), or poultry (adjusted HR, 1.04; 95% CI, 1.01 to 1.06) were significantly associated with incident CVD while fish intake was not (adjusted HR, 1.00; 95% CI, 0.98 to 1.02). Incident CVD included all fatal and nonfatal coronary heart disease, fatal and nonfatal stroke, fatal and nonfatal heart failure, and other CVD deaths.

Additionally, intake of processed meat (adjusted HR, 1.03; 95% CI, 1.02 to 1.05) or unprocessed red meat (adjusted HR, 1.03; 95% CI, 1.01 to 1.05) was associated with significantly increased all-cause mortality, while poultry and fish consumption was not. However, researchers also found the strength of the association between the intake of processed meat and CVD decreased with age, according to whether participants were younger than age 45 years, age 45 to 64 years, or age 65 years or older.

COMMENTARY

Compared with previous research, Zhong et al harmonized diet and other data across six cohorts, which largely attenuated the heterogeneities from previous studies and found significant positive associations of processed meat or unprocessed red meat intake with incident CVD and all-cause mortality. Although the observed effect sizes were small, the potential effects on public health can be significant, since these findings highlight how modification of dietary preferences may lead to meaningful effects on individual health outcomes. Interestingly, the authors identified a significant positive association between poultry intake and incident CVD. Although we cannot state conclusively, this finding could be related to the intake of fried chicken; thus, it may be more of an adverse effect from frying than the poultry itself. Regardless, it is clear that certain meat choices are healthier than others.

It would be valuable to continue to advise patients to limit the intake of both processed and unprocessed red meats. Poultry, such as chicken and turkey, are leaner meats and are lower in saturated fats, which makes poultry a better protein choice than red meat. Of course, fish may be one of the healthiest options to recommend, since it is an excellent source of minerals, such as iron, zinc, iodine, magnesium, and potassium, as well as omega-3 fatty acids, vitamins, calcium, and phosphorus. The bottom line is that when fruits and vegetables are not sufficient, it may be poultry and fish that remain the healthiest
options.

REFERENCES

  1. Daniel CR, Cross AJ, Koebnick C, Sinha R. Trends in meat consumption in the USA. Public Health Nutr 2011;14:575-583.
  2. Sinha R, Cross AJ, Graubard BI, et al. Meat intake and mortality: A prospective study of over half a million people. Arch Intern Med 2009;169:562-571.
  3. Kappeler R, Eichholzer M, Rohrmann S. Meat consumption and diet quality and mortality in NHANES III. Eur J Clin Nutr 2013;67:98-606.
  4. Wolk A. Potential health hazards of eating red meat. J Intern Med 2017;281:106-122.