Eating a healthy diet has many benefits for the body, but it also improves physical fitness. Eating vegetables, fruits, whole grains, nuts, legumes and fish, and limiting red meat and alcohol, translates into a better physical condition. A study published in the European Journal of Preventive Cardiology indicates that a healthy diet is associated with better physical fitness in middle-aged adults.
"This study provides some of the strongest and most rigorous data to date to support the connection between better diet and better fitness," said study author Michael Mi, from Beth Israel Deaconess Medical Center in Boston, USA. . "The improvement in physical fitness that we observed in the participants with better diets was similar to the effect of taking 4,000 more steps each day," adds the researcher.
Cardiorespiratory fitness reflects the body's ability to provide and use oxygen during exercise, and integrates the health of multiple organ systems, such as the heart, lungs, blood vessels, and muscles. It is one of the most powerful predictors of longevity and health.
Although exercise increases cardiorespiratory fitness, it is also the case that there are differences in fitness between people who do the same amount of exercise, suggesting that additional factors are contributing. A nutritious diet is associated with numerous health benefits, but it is not clear if it is also related to fitness.
This study examined whether a healthy diet is related to fitness in adults. The study involved 2,380 people from the Framingham Heart Study. The mean age was 54 years and 54% were women. Participants underwent a maximal effort cardiopulmonary exercise test on a cycle ergometer to measure VO2 max. This is the baseline assessment of fitness and indicates the amount of oxygen used during the highest intensity exercise possible.
Participants also completed the Harvard Semi-Quantitative Food Frequency Questionnaire to assess their intake of 126 foods over the past year, ranging from never or less than once a month to six or more servings a day. The information was used to rate diet quality using the Alternative Healthy Eating Index (AHEI; 0 to 110) and the Mediterranean Diet Score (MDS; 0 to 25), both related to heart health.
Higher scores indicated a higher-quality diet that emphasized vegetables, fruits, whole grains, nuts, legumes, fish, and healthy fats and limited red meat and alcohol.
The researchers assessed the association between diet quality and physical fitness after controlling for other factors that might influence the relationship, such as age, gender, total daily energy intake, body mass index, smoking status, cholesterol levels, blood pressure, diabetes and regular physical activity level. The mean of AHEI and MDS were 66.7 and 12.4, respectively. Compared to the mean score, an increase of 13 points on the AHEI and 4.7 on the MDS was associated with 5.2 percent and 4.5 percent more VO2 max, respectively.
"In middle-aged adults, healthy dietary patterns were strongly and favorably associated with physical fitness, even after accounting for usual activity levels. The relationship was similar in women and men, and more pronounced in those under the age of 54 years than in older adults", stressed Mi.
To uncover the possible mechanism linking diet and fitness, the researchers conducted further analyses. They examined the relationship between diet quality, fitness, and metabolites, which are substances produced during digestion and released into the blood during exercise.
A total of 201 metabolites (eg, amino acids) were measured in blood samples collected from a subset of 1,154 study participants. Some 24 metabolites were associated with poor diet and fitness, or favorable diet and fitness, after adjusting for the same factors considered in the previous analyses.
"Our metabolite data suggest that healthy eating is associated with better metabolic health, which could be a potential pathway leading to better fitness and exercise capacity," Mi said.
Regarding limitations, "this is an observational study and we cannot conclude that eating well causes better physical fitness, nor exclude the possibility of an inverse relationship, that is, that fit individuals choose to eat healthily."
"There are already many compelling health reasons to eat a high-quality diet, and we add one more with its association with fitness. A Mediterranean-style diet with fresh, whole foods and minimal processed foods, red meat, and alcohol It's a good starting point", concluded Mi.
