Older adults with the least inflammatory diet scores had 81% greater odds of favourable fitness. The study estimated VO2max — and cannot show diet caused it

Can a diet score tell us anything about how well an older adult's heart and lungs support exercise? Researchers used data from 906 community-dwelling adults in the Guangzhou Nutrition and Health Study, with an average age of 65.9 years. A validated 79-item food-frequency questionnaire supplied the ingredients for a Dietary Inflammatory Index, while a submaximal cycling test supplied an estimate of aerobic fitness.

Lower index scores represent a diet calculated to be less inflammatory. Adults in the lowest third of the score had 81% greater odds of meeting one definition of favourable cardiorespiratory fitness than those in the highest third. The odds ratio was 1.81, with a 95% confidence interval from 1.22 to 2.70. Their estimated VO2max also followed a favourable trend across the diet groups, although the statistical evidence was only just below the usual threshold at p = 0.048.

The result depended on how fitness was defined. One definition placed people in the sex-specific top quarter of estimated VO2max. The other asked whether the cycling workload kept them below 85% of their predicted maximum heart rate. The diet score was associated with the VO2max-based result, but not clearly with the heart-rate result: the odds ratio was 1.31, with a confidence interval from 0.94 to 1.84.

Physical activity complicated the picture in a useful way. The association between a lower inflammatory score and higher estimated VO2max was stronger among active participants. Compared with people whose diet score stayed high, those who moved to a low score had three times the odds of favourable fitness, while those whose score stayed low had about two and a half times the odds. Both estimates were imprecise: their confidence intervals were 1.20 to 7.51 and 1.28 to 4.87.

Those numbers do not prove that an anti-inflammatory diet builds fitness. The paper describes the analysis as cross-sectional, diet was self-reported, and VO2max was estimated with a submaximal protocol rather than measured during an all-out laboratory test. People who are fitter or more active may shop, eat, sleep and manage health conditions differently. Statistical adjustment cannot remove every such difference, and a dietary index does not identify one food responsible for the association.

The practical reading is therefore modest: a varied diet rich in minimally processed plant foods and regular physical activity often fit into the same healthy-ageing pattern, and this study found that its diet score tracked with one fitness estimate. A trial that changes diet while holding exercise support constant would be needed to learn whether the diet itself improves aerobic capacity. Anyone with heart, lung or mobility limitations should choose activity with their clinician rather than treating a food score as an exercise prescription.