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For long-term cardiovascular health, sticking to a healthy diet -- regardless of which one -- had a significant impact on hard outcomes, according to a study pooling three large prospective cohorts.

Comparing people scoring in the highest vs lowest quintiles on various diet scales, those who adhered best to any given diet had a lower risk of incident cardiovascular disease (CVD) events than those with the worst adherence:

• Healthy Eating Index-2015: adjusted HR 0.83 (95% CI 0.79-0.86)
• Alternate Mediterranean Diet Score: adjusted HR 0.83 (95% CI 0.79-0.86)
• Healthful Plant-Based Diet Index: adjusted HR 0.86 (95% CI 0.82-0.89)
• Alternate Healthy Eating Index: adjusted HR 0.79 (95% CI 0.75-0.82)

Overall, the study's findings were consistent across subgroups and for both components of the primary CVD outcome -- fatal coronary heart disease and stroke, according to Frank Hu, MD, PhD, of Harvard T.H. Chan School of Public Health in Boston, and colleagues in their paper published online in .

"None of the indexes were perfectly correlated, indicating that each dietary score represents a unique combination of dietary constituents," they noted. For example, fish intake was counted as adhering to the Alternate Mediterranean Diet Score and non-adherent to the Healthful Plant-Based Diet Index.

"Our findings provide support for the recommendations of the that it is not necessary to conform to a single dietary plan to achieve healthy eating," the researchers said, adding that they couldn't say whether any diet was superior to another.

The 2015-2020 dietary guidelines had been widely critiqued for the focus on dietary patterns rather than on individual foods and not following recommendations of the U.S. Dietary Guidelines Advisory Committee.

The 2020-2025 iteration of those diet guidelines is underway, with a public comment period that ended earlier this month.

Hu's study was based on 5.2 million person-years of total follow-up from women enrolled prospectively in the Nurses' Health Study I (n=74,930; 1984-2016) and II (n=90,864; 1991-2017) and from men in the Health Professionals Follow-up Study (n=43,339; 1986-2012). People with CVD, cancer, or diabetes at baseline were excluded.

Every 2 to 4 years, participants in the three cohort studies had reported information such as age, weight, physical activity, smoking status, multivitamin use, and aspirin use.

A validated food frequency questionnaire was also administered, asking respondents on how often they consumed a standard portion size of each food in the past year. Analysis of the nutrient and food components reported allowed Hu's group to calculate adherence to various dietary patterns.

One key limitation of the study was its observational nature, which left room for residual and unmeasured confounding, the investigators acknowledged.

Moreover, self-reported dietary assessments have been criticized as inherently subject to measurement error and misclassification.

Hu's team also noted the limited generalizability of their findings given that study participants were all health professionals and predominantly white.

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