How Do Plant-based Foods Reduce Type 2 Diabetes Risk?

TOPLINE:

A higher intake of lignans (found in plant-based foods such as seeds, whole grains, some fruits and vegetables, and coffee, tea, and cocoa) is linked to a reduced risk for type 2 diabetes (T2D), especially in individuals with obesity or premenopausal women.

METHODOLOGY:

• Lignans, polyphenolic compounds abundant in plant-based foods, are the primary dietary source of phytoestrogens in Western diets and are associated with a reduced risk for cardiometabolic conditions, but the relative associations of individual lignans with T2D are unknown.
• Researchers assessed the associations between the risk for T2D and the intake of total and four primary lignans using the data of 201,111 participants (mean age, 44.7 years; 80.2% women; 96.7% White individuals) from three large prospective US cohorts with over 30 years of follow-up, as well as the association between lignan intake and A1c in 496 participants from the Men’s Lifestyle Validation Study (MLVS).
• For the three large cohorts, lignan intake (total, secoisolariciresinol, matairesinol, pinoresinol, and lariciresinol) was assessed using a validated food frequency questionnaire updated every 2-4 years and categorized into quintiles. For MLVS, diet was assessed by two sets of 7-day diet records and presented as percentage changes in A1c for linear increases in lignan intake.
• Incident T2D was confirmed using diagnostic tests, symptoms, hypoglycemic medication, elevated glucose by several measures.

TAKEAWAY:

• Across the three cohorts, 20,291 cases of T2D were recorded in the full follow-up.
• Higher intakes of total and individual ligands, except for lariciresinol, were associated with about 8%-27% lower T2D incidents (approximate hazard ratio [HR], 0.72-0.93)
• Of the individual lignans, secoisolariciresinol (but not others) showed a significant inverse association with the risk for T2D among those with a body mass index ≥ 30 (HR, 0.75; 95% CI, 0.71-0.79) and premenopausal women (HR, 0.67; 95% CI, 0.65-0.69).
• The dietary intake of lignans assessed using the 7-day diet records in MLVS was associated with lower levels of A1c (percentage changes ranging from −0.92% to −1.50%.

IN PRACTICE:

“Our findings underscore the importance of a healthy plant-based diet rich in lignan-containing foods, including flaxseed products, whole grains, and coffee for the primary prevention of T2D,” the authors wrote.

SOURCE:

The study, led by Siyue Wang, PhD, Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, and the School of Public Health, Peking University, Beijing, China, was published online in JAMA Network Open.

LIMITATIONS:

The study’s limitations include the potential for measurement errors in dietary assessments. Flax seed, the most concentrated source of lignans, was not assessed until midway through the three large cohort follow-ups, and this may have resulted in misclassification of the intake levels of secoisolariciresinol. The lack of diversity in the socioeconomic status and race within the population may restrict the generalizability of the findings. Despite making multivariable adjustments, residual confounding cannot be fully ruled out.

DISCLOSURES:

The three cohort studies were supported by grants from the National Institutes of Health. The authors declared no conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.