What is the relationship between adherence to dietary guidelines and recommendations or specific dietary patterns, assessed using reduced rank regression analysis, and risk of type 2 diabetes?
The goal of this systematic review
project is to identify patterns of food and beverage intake that promote health and prevent disease. Historically, most dietary guidance has been based on research conducted on individual food components or nutrients. Dietary patterns
are defined as the quantities, proportions, variety or combination of different foods, drinks and nutrients (when available) in diets, and the frequency with which they are habitually consumed. Reduced rank regression (RRR) is a statistical method that determines dietary patterns (combinations of food intake) that explain as much variation as possible among a set of response variables related to a health
outcome of interest. It is an a posteriori
method since it uses both existing evidence and exploratory statistics. The objective of this systematic review was to assess the relationship between patterns of food and beverage intake identified using RRR
, and risk for T2D
There is insufficient evidence, due to a small number of studies, to examine the relationship between dietary patterns
derived using RRR
and risk of T2D
. The differences in the methods used and populations studied made it difficult to compare results, and therefore no conclusions were drawn. (DGAC Grade: Not Assignable
Literature searches were conducted using PubMed, Embase, Navigator (BIOSIS, CAB Abstracts and Food Science and Technology Abstracts) and Cochrane databases to identify studies that evaluated the association between dietary patterns
derived using RRR
analysis and risk of T2D
. Studies that met the following criteria were included in the review:
- Human subjects
- Ages: Two years and older
- Healthy and those with elevated chronic disease risk
- Individuals with chronic disease.
- Published in English in a peer-reviewed journal
- Sample size: Minimum of 30 subjects per study arm
- Dropout rate less than 20%
- Study assesses dietary intake using RRR analysis
- Study considered diabetes and risks of diabetes
- Subjects from countries with high or very high human development (based on the 2011 Human Development Index)
- The date range for the conduct of the studies was unlimited.
The results of each included study were summarized in evidence worksheets (including a study quality rating) and evidence table. A group of subject matter experts were involved in a qualitative synthesis of the body of evidence, development of a conclusion statement and assessment of the strength of the evidence (grade) using pre-established criteria including evaluation of the quality, quantity and consistency, magnitude of effect and generalizability of available evidence.
- Three prospective cohort studies examined dietary patterns derived using RRR analysis and their association with T2D incidence
- The studies ranged in size from 880 to 6,699 subjects
- Two of the studies were conducted in the United States and one in the United Kingdom
- The studies ranged in duration from 5.2 years to 11.6 years
- Comparison across studies was limited by the small number of studies, differences in methodology and in the populations studied.
- No conclusions were drawn.
The ability to draw a gradable conclusion was limited due to the following issues:
- All three studies used different types of biomarkers as response variables, such as PAI-1 and fibrinogen; HOMA-IR index; and BMI, fasting glucose, TG, HDL and hypertension, making it difficult to make comparisons across these studies
- The dietary patterns derived in each of these studies were directly linked to the response variables selected; therefore, the variation in the response variables used suggest that the resulting dietary patterns may not be comparable
- There were variations in dietary assessment methods used to assess dietary intake as well as the food groupings using in the analyses across the studies. These methodological differences make it difficult to compare the resulting dietary patterns across studies and to determine how these differences may have contributed to differences in relationships between the patterns and type 2 diabetes risks.
- The studies were not consistent in their use of confounders in the analyses. For example, alcohol intake was not included as a confounder in one study, and alcohol, BMI and smoking status were not controlled for in another study.
There was a positive association between derived dietary patterns that included meat intake and incident T2D
in the two studies that used biomarkers as response variables, though the definitions of meat differed. However, because there were so few studies available, variability in the methodology used and different populations considered, there was insufficient information from which to assess consistency or draw conclusions about the relationship between dietary patterns derived using RRR and risk of T2D.