Consistently consuming more fruit, vegetables, and whole grains is associated with better fitness levels equal to walking an additional 4,000 steps per day, according to a new study that was recently published in the European Journal of Preventive Cardiology.
The research aimed to examine whether a healthy diet is associated with physical fitness in adults. The study included 2,380 participants in the Framingham Heart Study—a long term, multi-generational study designed to identify common traits that contribute to cardiovascular disease. The average age of the participants was 54 years, and 54 percent of them were women.
In addition to completing a high-intensity fitness assessment, participants completed the Harvard semi-quantitative food frequency questionnaire to assess intake of dietary items during the last year.
Researchers used their responses to rate diet quality using two tests associated with heart health: the Alternative Healthy Eating Index (AHEI) and Mediterranean-style Diet Score (MDS). Higher scores indicated a diet that prioritizes vegetables, fruits, whole grains, nuts, legumes, fish, and healthy fats, while limiting red meat and alcohol.
The researchers evaluated the association between diet quality and fitness after controlling for other factors that could influence the relationship, including age, sex, total daily energy intake, body mass index, smoking status, cholesterol levels, blood pressure, diabetes, and routine physical activity level.
The result? In the large observational study of community-dwelling individuals, researchers found that a healthy diet is associated with greater fitness—to a magnitude similar to that observed for taking 4,000 more steps per day.
“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,” study author Dr. Michael Mi of Beth Israel Deaconess Medical Center in Boston, MA said in a statement.
“The improvement in fitness we observed in participants with better diets was similar to the effect of taking 4,000 more steps each day.”
Fitness and heart health
Cardiorespiratory fitness reflects the body’s ability to provide and use oxygen for exercise, and it integrates the health of multiple organ systems, such as the heart, lungs, blood vessels, and muscles. The researchers say it is one of the most powerful predictors of longevity and health.
While exercise increases cardiorespiratory fitness, there are differences in fitness among people who exercise the same amount, suggesting that additional factors contribute.
“In middle-aged adults, healthy dietary patterns were strongly and favorably associated with fitness even after taking habitual activity levels into account,” Mi said. “The relationship was similar in women and men, and more pronounced in those under 54 years of age compared to older adults.”
To discover the potential mechanism linking diet and fitness, the researchers performed 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 were measured in blood samples collected in a subset of 1,154 study participants.
The results showed that some 24 metabolites were associated with either poor diet and fitness, or with favorable diet and fitness, after adjusting for the same factors considered in the previous analyses.
“Our metabolite 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,” Mi said.
“There are already many compelling health reasons to consume a high-quality diet, and we provide yet another one with its association with fitness,” Mi concluded. “A Mediterranean-style diet with fresh, whole foods and minimal processed foods, red meat and alcohol is a great place to start.”
Plant-based diet and cardiovascular disease
Many previous studies that examined the link between diet and cardiovascular disease found that a plant-based diet lowers the risk for such heart problems.
One study published in the medical journal JAMA Internal Medicine found that sticking closely to one of four healthy eating patterns (Healthy Eating Index 2015, Alternate Mediterranean Diet, Healthful Plant-based Diet Index, and Alternate Healthy Eating Index) was associated with lower risk of premature death from all causes, and from cardiovascular disease, cancer, and respiratory disease.
The researchers believe that the reason for the similarity in the associations between diet quality and death is that all four dietary patterns share the key component of being high in plant foods, specifically whole grains, fruits, vegetables, nuts, and legumes. And the researchers hope their findings will help inform any updates to the current Dietary Guidelines for Americans (DGAs).
“Our findings support the recommendations of the current DGAs to achieve long-term health benefits by adherence to various healthy eating patterns that can be adopted based on individuals’ health needs, food preferences, and cultural traditions, although all these diet patterns encourage high consumption of healthy plant-based foods,” the study concluded.