Wellness Check: Nutrition

Red meat consumption may be associated with an increased risk of type 2 diabetes

1. In this prospective cohort study, red meat consumption was positively and linearly associated with the risk of developing type 2 diabetes (T2D).

2. Furthermore, substituting one serving of nuts, legumes, or dairy per day for total, processed, or unprocessed red meat was associated with a significant decrease in T2D risk.

Evidence Rating Level: 2 (Good)

Type 2 diabetes (T2D) is a highly prevalent chronic disease that is associated with several lifestyle factors. One lifestyle factor in particular that has been implicated in the risk of developing T2D is red meat consumption. However, prior studies investigating this association have had several methodological challenges, given the long course it takes to develop T2D. Thus, the present study aimed to investigate the association between red meat consumption and the risk of developing T2D and the impact of substituting protein sources for red meat on this association with extended follow-up.

This prospective cohort study included 216,695 participants from three studies: the Nurses’ Health Study (NHS), NHS II, and Health Professionals Follow-up Study (HPFS). Across the three studies, patients aged 25 to 75 at recruitment were included, which began in 1976 for the earliest study. Female participants with an energy intake of <500 or >3500 kcal/day were excluded, while male participants with an energy intake of <800 or >4200 kcal/day were excluded. Further, participants were excluded if they had a history of diabetes, myocardial infarction, angina, stroke, coronary artery bypass graft, or cancer or if they had missing data regarding age or baseline red meat consumption. Red meat and other dietary consumption were assessed every 2 to 4 years using food frequency questionnaires (FFQs), and T2D incidence was obtained from biennial questionnaires. The primary outcome was the risk of developing diabetes based on red meat consumption.

The results demonstrated that there was a positive and linear relationship between red meat consumption and the risk of developing T2D. The risk of developing T2D was highest for total red meat consumption, followed by processed red meat and unprocessed red meat. In investigating the role of other protein sources on T2D, the study found that substituting one serving per day of nuts and legumes for red meat resulted in a decreased risk of T2D and that this reduction was greatest when substituting for processed red meat. A similar finding was found for dairy products, whereby substituting one serving per day of dairy products for red meat was associated with a decreased risk of developing T2D. However, this study was limited by the fact that all included participants were health professionals, which may have limited the generalizability of the findings. Nonetheless, the present study further demonstrated the impact of red meat consumption on the risk of developing T2D.

Dietary factors early in life may influence the development of celiac disease

1. In this cohort study, diets high in vegetable fats and milk at 9 months were associated with a decreased risk of developing celiac disease autoimmunity (CDA).

2. However, at 24 months, a diet high in wheat, vegetable fats, and juices and diets low in milk, meat, and oats were associated with an increased risk of developing CDA and celiac disease.

Evidence Rating Level: 2 (Good)

An intolerance to dietary gluten characterizes celiac disease, and both genetic and environmental factors have been implicated in the development of the condition. Previous studies have indicated that a higher gluten intake early in life is associated with an increased risk of developing celiac disease autoimmunity (CDA) and celiac disease in those with genetic risks. However, the impact of other dietary habits early in life on the risk of CDA and celiac disease has not been well characterized. Thus, the present study aimed to evaluate the role of dietary patterns, other than gluten intake, early in life on the risk of developing CDA and celiac disease in genetically at-risk children.

This cohort study included 6,726 participants from The Environmental Determinants of Diabetes in the Young (TEDDY) study, which included 15 years of follow-up from 2004 to 2010. Study participants were followed from 6 centers across the United States and Europe. Participants were included if they were at genetic risk of developing type 1 diabetes or celiac disease. Those with missing dietary data between 9 and 24 months or those who did not receive screening for celiac disease were excluded from the study. Dietary intake was assessed with three-day food records at 9, 12, 18, and 24 months, while celiac disease and CDA was assessed via measurement of transglutaminase autoantibodies (tTGAs) at 24 months and continued annually for the remainder of the study period. Participants were followed until November 2020. The primary outcome was the association between various food groups and the risk of developing CDA and celiac disease.

The results demonstrated that a dietary pattern high in vegetable fats and milk at 9 months was associated with a reduced risk of developing CDA, even after adjusting for gluten intake. Diets high in wheat and vegetable fats were associated with an increased risk of CDA at 24 months after adjusting for gluten intake. Similarly, a dietary pattern high in wheat, vegetable fats, and juices and those low in milk, meat, and oats were associated with an increased risk of CDA and celiac disease. However, the study is limited by the use of general dietary patterns, which does not allow for the assessment of individual foods. Nonetheless, the present study suggested that dietary factors other than gluten influence the development of CDA and celiac disease early in life.

Several nutrients may be associated with improved cognitive function later in life

1. In this cross-sectional study, nutrients that were associated with an increase in cognitive function included vitamin A, vitamin E, thiamin, riboflavin, vitamin B6, folate, magnesium, potassium, zinc, vitamin K, lutein, and zeaxanthin.

2. Furthermore, in females, vitamin A, vitamin C, magnesium, vitamin K, potassium, and dietary fiber were associated with a decreased risk of depression.

Evidence Rating Level: 3 (Average)

As individuals age, the risk of cognitive decline and poor mental health increases. Although cognitive changes are inevitable throughout the aging process, evidence suggests that lifestyle factors, such as diet, may influence the risk of cognitive decline in older age. However, there is still much to be discovered with regard to the specific dietary factors that influence cognition and mental health later in life. Thus, the present study aimed to assess the relationship between the intake of various nutrients and cognitive function and depression.

This cross-sectional study included 2,713 participants with valid cognitive function data and 2,943 participants with valid depression score data from the National Health and Nutrition Examination Survey (NHANES) in the United States. Participants aged 60 or older who participated in NHANES between 2011 and 2014 were included. Participants with incomplete or missing dietary data were excluded. Participants underwent a home interview, cognitive function testing, and the Dietary Supplement and Prescription Medication Section (DSQ) of the Sample Person Questionnaire with an interviewer. The Patient Health Questionnaire (PHQ-9) was used to assess depression. The primary outcome was the association between the intake of various nutrients with cognitive functioning and depression scores.

The results demonstrated that several nutrients, including vitamin A, vitamin E, thiamin, riboflavin, vitamin B6, folate, magnesium, potassium, zinc, vitamin K, lutein, and zeaxanthin were associated with an increase in cognitive function in both men and women. Furthermore, vitamin A, vitamin C, magnesium, vitamin K, potassium, and dietary fiber were associated with a decreased risk of depression in women. Meanwhile, there were no nutrients that demonstrated a significant association with depression scores in men. However, the study was limited by the small proportion of the study population that had moderate to severe depression, which may have limited the generalizability of these findings to that population. Nonetheless, the present study demonstrated that certain nutrients can positively impact cognitive function and mental health status later in life.

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