Study of macronutrient intake finds proportions of carbs, proteins and fats in the diet have differing effects on mortality risk for men and women with type 2.
Researchers are investigating the relationship between the intake of macronutrients, such as carbohydrates, proteins, and fats, and disease risk. A UK based study found a positive relationship between dietary fat intake and CVD mortality in women, but not men, while a French study reported an inverse relationship between protein intake and mortality in patients with hypertension who did not have chronic kidney disease. A 2020 Taiwanese study aimed to study dietary patterns in a specific patient population, those with type 2 diabetes, and relate the dietary patterns to mortality. Investigation of dietary macronutrient composition in the diets of those with type 2 diabetes is critical as the annual incidence of diabetes has grown drastically, causing the deaths of 5 million people worldwide, a sharp increase from the less than 1 million deaths in 2000.
The Taiwanese retrospective cohort study gathered data from China Medical University Hospital’s (CMUH) Diabetes Care Management Program (DCMP). Upon registration in the DCMP, patients underwent a series of baseline medical tests and measurements, and a standardized questionnaire was utilized to obtain lifestyle, diet, and medical history. The inclusion criteria for the study required that participants have a diagnosis of type 2 diabetes and be 30 years of age or older. Participants were excluded if they had type 1 diabetes, gestational diabetes, or if their laboratory, dietary, or other necessary records were unavailable. The final study cohort consisted of 15,289 participants who were required to participate in a 24-hour dietary recall (24HDR). The 24HDR is a structured interview facilitated by dietitians to ascertain detailed information on a patient’s dietary intake in the last 24 hours. The data was then analyzed for micronutrient content and total caloric intake. Primary outcomes of the study were all-cause mortality and expanded and non-expanded cardiovascular disease-related mortality. Death records were obtained from the National Death Datasets, which utilizes ICD-9 codes, so researchers were able to determine the cause of death.
Of the 15,289 participants, after a mean follow-up of 7.4 years, 2,784 deaths were reported. Out of these 2,784 deaths, 1,287 were expanded CVD deaths, and 1,497 were non-expanded CVD deaths. Those who died tended to be older, male, smokers, and have low BMI. They had higher A1c and greater incidences of hypertension, hyperlipidemia, stroke, and coronary artery disease. The study found that those with a 43-52% carbohydrate intake were found to have a 14-15% lower risk of all-cause mortality as well as a 17-22% decreased risk of expanded CVD mortality. Participants whose dietary intake was 15-16% protein also had a 15% lower risk of all-cause mortality and a 20% lower risk of expanded CVD mortality. Women who reported that over 39% of their daily intake was fat had a 35% increased risk of expanded CVD mortality, but men with 35-38% fat intake had a 20% lower all-cause mortality rate.
The study’s strengths included a large sample size with a long follow-up period, data collection from a standardized procedure (24HDR) overseen by dietitians, and patient records obtained from reputable national databases. However, the study was severely limited by the fact that there was only one 24HDR due to clinical constraints. The study would have benefitted greatly from having more 24HDRs over a more extended period to understand the patient’s dietary habits better. A single 24HDR may not be appropriately indicative of a patient’s long-term dietary composition. Another limitation of the study was that it did not differentiate between fat types, such as saturated fatty acids, polyunsaturated fatty acids, monounsaturated fat, or trans-fat. Additionally, this was a hospital-based study, which may not be representative of the Taiwanese population.
Furthermore, because the study was only in Taiwanese patients, it may not be generalizable to other populations. Despite the limitations, the study results provide important implications for the use of ethnic-based dietary guidelines. Future studies in other populations could provide recommendations for patients of other ethnic or demographic groups.
- Dietary fat intake is more dangerous for women than men when it comes to expanded CVD mortality.
- Higher levels of dietary fat consumption in men are correlated with decreased all-cause mortality.
- A 43-52% carbohydrate intake is associated with a 15% lower risk of all-cause mortality.
Reference for “Macronutrient Intake Impacts Mortality for T2D”:
Lin, Cheng-Chieh, et al. “Dietary Macronutrient Intakes and Mortality among Patients with Type 2 Diabetes.” Nutrients, vol. 12, no. 6, 2020, p. 1665., doi:10.3390/nu12061665.
Sameen Khan, Pharm.D. Candidate, USF College of Pharmacy