In the present report, we show that adherence to dietary guidance for healthy eating, the AHEI, is associated with reversion of the MetS in a middle-aged population. Although several studies have investigated the diet-to-MetS prevalence and incidence relationships, the impact of diet on MetS reversion has only been studied in two clinical trials assessing adherence to the Mediterranean diet in two Mediterranean countries. One trial of 180 Italian subjects found the Mediterranean diet intervention to lead to reversion of MetS (3
), the other larger trial (n
= 1,224, Spanish) suggested that the observed effect was due to the effect of nut supplements rather than the Mediterranean diet as a whole (4
). Even though the clinical utility of MetS as an independent predictor of CVD has been challenged (11
), our findings, from a non-Mediterranean country, are novel and strengthen evidence of the potential impact of diet in countering increasing levels of risk factors associated with CVD and type 2 diabetes.
We observed a stronger impact of AHEI on MetS reversion in participants with central obesity and high triglycerides. Among all baseline MetS case subjects, AHEI was associated with reversion of the high triglyceride component but not the central obesity component. Thus, reduction of visceral fat (12
) leading to a decrease in the flux of free fatty acids and increased insulin resistance—a key feature in MetS pathophysiology (13
)—seems an unlikely explanation for our findings. However, further research is needed to examine these and other plausible mechanisms. These may include counteracting oxidative stress (and related insulin resistance) (14
) via antioxidants from fruits, vegetables, and long-term multivitamin use and the lowering of high triglyceride levels—linked to reduction of inflammation processes involved in MetS (15
)—as a result of increased consumption of polyunsaturated fat, nuts, and soy and a reduced consumption of trans
Limitations of this study include the small sample size that does not fully represent the British population (6
) and that does not allow ethnic group substratification other than White or non-White, thereby limiting the generalizability of our findings; the lack of objective measure of physical activity; and the use of the FFQ, recognized to be less precise than diary questionnaires, to assess diet.
Despite these limitations, our findings emphasize the potential benefits of adherence to the dietary recommendations of the AHEI in middle-aged individuals with MetS, especially those with central obesity or high triglyceride levels.