Processed meat: the real villain?

Abstract

Meat is a food rich in protein, minerals such as iron and zinc as well as a variety of vitamins, in particular B vitamins. However, the content of cholesterol and saturated fat is higher than in some other food groups. Processed meat is defined as products usually made of red meat that are cured, salted or smoked (e.g. ham or bacon) in order to improve the durability of the food and/or to improve colour and taste, and often contain a high amount of minced fatty tissue (e.g. sausages). Hence, high consumption of processed foods may lead to an increased intake of saturated fats, cholesterol, salt, nitrite, haem iron, polycyclic aromatic hydrocarbons, and, depending upon the chosen food preparation method, also heterocyclic amines. Several large cohort studies have shown that a high consumption of processed (red) meat is related to increased overall and cause-specific mortality. A meta-analysis of nine cohort studies observed a higher mortality among high consumers of processed red meat (relative risk (RR) = 1·23; 95 % CI 1·17, 1·28, top v. bottom consumption category), but not unprocessed red meat (RR = 1·10; 95 % CI 0·98, 1·22). Similar associations were reported in a second meta-analysis. All studies argue that plausible mechanisms are available linking processed meat consumption and risk of chronic diseases such as CVD, diabetes mellitus or some types of cancer. However, the results of meta-analyses do show some degree of heterogeneity between studies, and it has to be taken into account that individuals with low red or processed meat consumption tend to have a healthier lifestyle in general. Hence, substantial residual confounding cannot be excluded. Information from other types of studies in man is needed to support a causal role of processed meat in the aetiology of chronic diseases, e.g. studies using the Mendelian randomisation approach.

Associations between Dietary Patterns and Bile Acids—Results from a Cross-Sectional Study in Vegans and Omnivores

“…This positive correlation of bile acids with the derived pattern confirms the impact of food products rich in fat and particularly of animal origin on elevated bile acid concentrations [11,12,17], as also described in previous studies. In particular, processed meat, which is high in cholesterol and saturated fatty acids [53], contributed to this dietary pattern. Increasing intake of saturated fatty acids in the derived pattern was in line with this observation.…”

Processed red meat contribution to dietary patterns and the associated cardio-metabolic outcomes

“…The current analysis included red meat that underwent smoking, salting, curing, fermentation or other processing to enhance flavour or improve preservation ( 16 ) . It is important to consider the effects of these processing techniques, and the added ingredients, including salt, which may be contributing to the observed association between processed red meat and risk for incident CVD and T2D ( 2 , 6 ) . In a review by Micha et al which included twenty-seven observational studies (CVD; n 10; T2D; n 17) from ten countries, studies presented varying quantities of mean daily red meat intakes, with differing processed meat definitions and differing levels of confounder adjustment outlining the difficulties in reviewing this area ( 2 ) .…”

Chemical hazards in foods of animal origin

“…During the last decades, a considerable number of observational epidemiological studies have reported a positive association between high red meat and processed meat consumption and the risk to develop several chronic diseases, in apparent contradiction to the valuable nutritional composition of meat. High versus low red and/or processed meat consumption has been linked in meta-analyses to an increased risk of all-cause mortality (Rohrmann and Linseisen, 2016), colorectal cancer (Aune et al, 2013;Bouvard et al, 2015;Chan et al, 2011), coronary heart disease (Micha et al, 2010;updated by Micha et al, 2012) and type 2 diabetes (Micha et al, 2012;Pan et al, 2011) (Table 1). The increase in relative risk (RR) per unit change in consumption is comparable for the mentioned chronic diseases and for all-cause mortality, except for no effect of red meat consumption on cardiovascular disease in contrast to processed meat.…”

“…Because chronic diseases are multifactorial, a correct assessment of the effect of a single factor, in this case meat consumption, is dependent on correction for possible confounding factors by using appropriate statistical models. It is well known that low-meat eaters have in general a healthier lifestyle, for instance by consuming less alcoholic beverages, being no smokers, or performing more exercise; factors that all contribute to a lower risk of certain chronic diseases (Klurfeld, 2015;Rohrmann and Linseisen, 2016). The outcome of independent studies is variable, with several studies showing no significant effect due to lack of statistical power or simply because there is no effect.…”

“…Using markers as intermediate endpoints, e.g. blood cholesterol levels or faecal water DNA adducts, is also disputable because the link between a marker and the disease or mortality is often not unique (Rohrmann and Linseisen, 2016). Anyway, mechanistic studies do provide important information and insight into the associations, and do allow developing mitigation strategies in case specific associations appear to be robust and of global health concern.…”