Healthy diet tied to improved physical fitness

A recent study found an association between a healthy diet and greater physical fitness in middle-aged adults.

“Healthy dietary patterns are an important component of cardiovascular health, but it remains uncertain whether they are also related to cardiorespiratory fitness (CRF),” said the investigators, led by Dr Michael Mi of Beth Israel Deaconess Medical Center, Boston, Massachusetts, US.

“[In our study,] higher diet quality is associated with greater CRF cross-sectionally in a middle-aged community-dwelling sample, and metabolites highlight potential shared favourable effects on cardiometabolic health,” Mi said.

The trial included 2,380 individuals (mean age 54 years, 54 percent female) enrolled in the Framingham Heart Study. Participants completed food frequency questionnaires (FFQs) to evaluate the intake of 126 dietary items during the last year. To measure peak VO₂, participants underwent a cardiopulmonary exercise test using a cycle ergometer. [Eur J Prev Cardiol 2023;doi:10.1093/eurjpc/zwad113]

The researchers used peak VO₂ as this is the ‘gold standard’ assessment of CRF and indicates the amount of oxygen used during the highest possible exercise intensity.

After adjusting for age, sex, total daily energy intake, cardiovascular risk factors, and physical activity, 1 SD higher AHEI* and MDS** were associated with 5.2 percent (1.2 mL/kg/min; p<0.0001) and 4.5 percent (1.0 mL/kg/min; p<0.0001) greater peak relative VO₂, respectively. “[These improvements were] similar to the effect of taking 4,000 more steps each day,” said Mi.

Metabolite profiling

In participants with metabolite profiling (n=1,154), 24 metabolites were consistently associated with both dietary indices and peak VO₂ in multivariable adjusted models (false discovery rate <5 percent).

Metabolites that were positively associated with higher CRF and favourable diet quality included C38:7 phosphatidylcholine plasmalogen and C38:7 and C40:7 phosphatidylethanolamine plasmalogens, while those tied to lower CRF and poorer dietary quality included C6 and C7 carnitines, C16:0 ceramide, and dimethylguanidino valeric acid.

“[These] data suggest that eating healthily is associated with better metabolic health, which could be one possible way that it leads to improved fitness and ability to exercise,” explained Mi.

Strong, rigorous data

“[W]e captured dietary patterns with a widely used FFQ and two healthy dietary indices designed to reflect the best contemporary evidence for healthy eating,” the researchers noted. “Both the AHEI and MDS have been robustly associated with lower risk of cardiovascular and all-cause mortality and other health outcomes, and their components/scores are readily translatable to individuals or for use in intervention studies.”

However, this limits generalizability of the findings to all other dietary patterns, they pointed out. Further studies are thus warranted to assess dietary components that could directly affect CRF and whether supplementation with metabolites could help in improving exercise performance.

“[Nonetheless,] this study provides some of the strongest and most rigorous data thus far to support the connection that better diets may lead to higher fitness,” Mi said in a press release. “There are already many compelling health reasons to consume a high-quality diet, and we provide yet another one with its association with fitness.”

“A Mediterranean-style diet with fresh, whole foods and minimal processed foods, red meat, and alcohol is a great place to start,” Mi added.