Dietary patterns affect the risk for type 2 diabetes to a greater extent vs intake of specific food groups, according to findings from the Multi-Ethnic Study of Atherosclerosis (MESA), reported in the June 10 Online First issue of Diabetes Care.
“Each nutrient or food is part of a larger pattern consisting of many nutrients and foods, and thus, characterization of multiple, concurrent dietary exposures has particular relevance to health,” write Jennifer A. Nettleton, PhD, from the University of Texas Health Sciences Center in Houston, and colleagues. “Using data from the . . . MESA we evaluated the relations between type 2 diabetes risk and 1) PCA [principal components analysis]-derived dietary patterns and 2) a ‘low-risk’ food pattern score based on the intakes of foods previously associated with risk of type 2 diabetes.”
At baseline, from 2000 to 2002, a total of 5011 participants in MESA completed food frequency questionnaires. The study cohort consisted of white, black, Hispanic, and Chinese adults, aged 45 to 84 years and without cardiovascular disease or diabetes at baseline. At 3 follow-up examinations (2002 – 2003, 2004 – 2005, and 2005 – 2007), incident type 2 diabetes was determined on the basis of fasting serum glucose levels of more than 126 mg/dL, self-reported type 2 diabetes, or use of diabetes medication.
The investigators studied 2 types of dietary patterns: 4 empirically derived from PCA as well as the “low-risk food pattern,” defined as the weighted sum of whole grains, vegetables, nuts/seeds, low-fat dairy, coffee (positively weighted), red meat, processed meat, high-fat dairy, and soda (negatively weighted).
A PCA-derived dietary pattern characterized by high consumption of tomatoes, beans, refined grains, high-fat dairy, and red meat was associated with an 18% greater risk for diabetes (hazard ratio [HR] per 1-score SD, 1.18; 95% confidence interval [CI],1.06 – 1.32; P for trend = .004 ). In contrast, the PCA-derived dietary pattern characterized by high consumption of whole grains, fruit, nuts/seeds, green leafy vegetables, and low-fat dairy was associated with a 15% lower risk for diabetes (HR per 1-score SD, 0.85; 95% CI, 0.76 – 0.95; P for trend = .005).
Although the “low-risk food pattern” was also inversely associated with diabetes risk (HR per 1-SD score, 0.87; 95%CI, 0.81 – 0.99; P for trend = .04), individual component food groups were not independently associated with diabetes risk. Sex and race/ethnicity did not affect the observed associations.
Limitations of this study include possible bias of risk estimates; inability to rule out that other dietary patterns are importantly related to type 2 diabetes; race/ethnic–stratified analyses limited by small sample sizes, especially in the Chinese participants; and possible confounding by demographic and nondietary lifestyle factors.
“Multiple food groups collectively influence type 2 diabetes risk beyond that of the individual food groups themselves,” the study authors write. “These findings underscore the importance of the collective influence of multiple food groups in the development of type 2 diabetes and suggest that individuals wishing to decrease the risk of type 2 diabetes, regardless of their race/ethnicity, focus on increasing intake of several key food groups, including whole grains, low-fat dairy, fruits & vegetables, and nuts/seeds, while decreasing their intake of red/processed meats, high-fat foods, and sugared soda beverages.”
The National Heart, Lung, and Blood Institute supported this study. The study authors have disclosed no relevant financial relationships.
Diabetes Care. Published online June 10, 2008.
Clinical Context
Diet may reduce the risk for type 2 diabetes independent of body weight and other risk factors. Whole grains, nuts/seeds, coffee, low-fat dairy, and vegetables have been associated with a lower risk for diabetes, whereas processed meats, sugar-sweetened beverages, and white potatoes have been associated with an increased risk, but more information is needed on the association between diet patterns and diabetes risk in multiethnic populations.
This is a longitudinal cohort study (the MESA study) of a diverse group consisting of white, black, Chinese, and Hispanic adults in 6 US field centers to examine the risk for type 2 diabetes associated with dietary patterns distinguished with use of PCA and a “low risk” pattern score.
Study Highlights
Included were 6814 adults aged 45 to 84 years at baseline who were recruited to study the progression of subclinical cardiovascular disease and lifestyle.
There were 3 examination cycles, each lasting 1 to 2 years (2002 – 2003, 2004 – 2005, and 2005 – 2007).
Data from 5011 adults were used for this study (2177 whites, 1205 blacks, 1016 Hispanics, 613 Chinese) after exclusion of those with diabetes at baseline.
Fasting serum glucose level was measured at each examination with the glucose oxidase method.
Type 2 diabetes was defined as a fasting serum glucose level of 126 mg/dL or higher, self-reported diabetes, or any use of antidiabetic medication.
Usual dietary intake was quantified with a 120-item food frequency questionnaire, which was developed in the Block format and validated for the ethnic groups studied.
The food frequency questionnaire was modified to include unique Chinese foods and culinary practices.
9 frequency options were given for each food choice ranging from “rare or never” to “6+ times per day.”
2 types of dietary pattern scores were derived.
The PCA method used scores for 4 sets of patterns each composed of 47 food groups.
The 4 PCA patterns were “Fats & Processed Meats,” “Vegetables & Fish,” “Beans Tomatoes & Refined Grains,” and “Whole Grains & Fruit.”
A score was calculated for each participant based on daily serving size and factor loading, with higher scores representing greater adherence to the pattern.
The low-risk food pattern score was based on intakes of 10 food groups previously associated with a low risk for diabetes.
Low-risk patterns of food for diabetes include high intake of grains; low-fat dairy; coffee; nuts/seeds; fruits and vegetables; and low intake of processed meats, white potatoes, and soda.
A score was calculated by weighting each food group associated with low risk as positive and with high risk as negative.
At 5 years of follow-up, type 2 diabetes developed in 8.2% of participants, with the highest incidence in Hispanics (11.3%), then blacks (9.5%), Chinese (7.7%), and whites (6.3%).
The “Beans, Tomatoes & Refined Grains” pattern was associated with the highest risk for diabetes (P for trend = .004) with an 18% higher risk for every 1-SD increase in score.
The “Whole Grains & Fruit” pattern was associated with lowest risk (P for trend = .005), with a 15% lower risk for every 1-SD increase in score.
The association persisted after adjustment for waist circumference and body weight.
The low-risk pattern score was associated with lower risk for type 2 diabetes, with participants in the fifth quintile having a 38% lower risk for diabetes vs those in the lowest quintile (HR, 0.62).
Each 1-SD increase in score corresponded to a 13% lower risk for type 2 diabetes (HR, 0.87).
This association was independent of body weight and waist circumference.
No individual food group component of the low-risk food pattern was significantly associated with the risk for diabetes.
However, the food within the food groups showed the expected direction for increased and reduced risk for type 2 diabetes.
The associations seen were not dependent on ethnicity.
The authors concluded that the “Whole Grains & Fruit” pattern was associated with a lower risk for type 2 diabetes, whereas “Beans, Tomatoes & Refined Grains” pattern was associated with a higher risk for type 2 diabetes.
Pearls for Practice
The “Whole Grains & Fruit” food pattern is associated with a lower risk for type 2 diabetes, whereas the “Beans, Tomatoes & Refined Grains” pattern is associated with a higher risk for type 2 diabetes.
Low-risk patterns of food for type 2 diabetes include high intake of grains; low-fat dairy; coffee; nuts/seeds; fruits and vegetables; and low intake of processed meats, white potatoes, and soda.
