Replacing the consumption of red meat with other major dietary protein sources and risk of type 2 diabetes mellitus: a prospective cohort study

BACKGROUND

Greater consumption of red meat has been associated with a higher risk of type 2 diabetes mellitus (T2DM). A decreased intake of red meat and simultaneous increased intake of other high-protein foods may be associated with a lower risk of T2DM. These analyses of specific food replacements for red meat may provide more accurate dietary advice.

OBJECTIVE

We examined the association between a decrease in intake of red meat accompanied by an increase in other major dietary protein sources and risk of T2DM.

METHODS

We prospectively followed 27,634 males in the Health Professionals Follow-up Study, 46,023 females in the Nurses' Health Study, and 75,196 females in the Nurses' Health Study II. Diet was assessed by a validated FFQ and updated every 4 y. Cox proportional hazards models adjusted for T2DM risk factors were used to model the food replacements. We calculated HRs and 95% CIs for the T2DM risk associated with replacements of 1 daily serving of red meat with another protein source.

RESULTS

During 2,113,245 person-years of follow-up, we identified 8763 incident T2DM cases from 1990 to 2013. In the pooled analyses, a decrease in total red meat intake during a 4-y period replaced with another common protein food was associated with a lower risk of T2DM in the subsequent 4-y period. The HR (95% CI) per 1 serving/d was 0.82 (0.75, 0.90) for poultry, 0.87 (0.77, 0.98) for seafood, 0.82 (0.78, 0.86) for low-fat dairy, 0.82 (0.77, 0.86) for high-fat dairy, 0.90 (0.81, 0.99) for eggs, 0.89 (0.82, 0.98) for legumes, and 0.83 (0.78, 0.89) for nuts. The associations were present for both unprocessed and processed red meat, although stronger for the replacement of processed red meat.

CONCLUSIONS

Replacing red meat consumption with other protein sources was associated with a lower risk of T2DM.

Plant foods, dietary fibre and risk of ischaemic heart disease in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort

BACKGROUND

Epidemiological evidence indicates that diets rich in plant foods are associated with a lower risk of ischaemic heart disease (IHD), but there is sparse information on fruit and vegetable subtypes and sources of dietary fibre. This study examined the associations of major plant foods, their subtypes and dietary fibre with risk of IHD in the European Prospective Investigation into Cancer and Nutrition (EPIC).

METHODS

We conducted a prospective analysis of 490 311 men and women without a history of myocardial infarction or stroke at recruitment (12.6 years of follow-up, n cases = 8504), in 10 European countries. Dietary intake was assessed using validated questionnaires, calibrated with 24-h recalls. Multivariable Cox regressions were used to estimate hazard ratios (HR) of IHD.

RESULTS

There was a lower risk of IHD with a higher intake of fruit and vegetables combined [HR per 200 g/day higher intake 0.94, 95% confidence interval (CI): 0.90-0.99, P-trend = 0.009], and with total fruits (per 100 g/day 0.97, 0.95-1.00, P-trend = 0.021). There was no evidence for a reduced risk for fruit subtypes, except for bananas. Risk was lower with higher intakes of nuts and seeds (per 10 g/day 0.90, 0.82-0.98, P-trend = 0.020), total fibre (per 10 g/day 0.91, 0.85-0.98, P-trend = 0.015), fruit and vegetable fibre (per 4 g/day 0.95, 0.91-0.99, P-trend = 0.022) and fruit fibre (per 2 g/day 0.97, 0.95-1.00, P-trend = 0.045). No associations were observed between vegetables, vegetables subtypes, legumes, cereals and IHD risk.

CONCLUSIONS

In this large prospective study, we found some small inverse associations between plant foods and IHD risk, with fruit and vegetables combined being the most strongly inversely associated with risk. Whether these small associations are causal remains unclear.

Food substitution models for nutritional epidemiology

The advantage of using specified substitution analysis in nutritional epidemiology has been clearly demonstrated in studies of macronutrient intake and disease risk. However, the method has not been widely applied in studies of food intake. The aim of this article is to describe and compare the interpretation and application of different food substitution models in epidemiologic studies on diet and disease development. Both theoretically and in the context of a specific example, we discuss methodologic issues to be considered, including modeling of food substitutions using diet at a single time point or at multiple time points (focusing on dietary changes), choice of substitution unit, adjustment for total energy intake, and adjustment for confounding. We argue that specified food substitution analyses can be used to identify optimal food composition of the diet and that these analyses are thus highly relevant to inform public health policy decision makers.