Fruits and vegetables are beneficial for health, but not all provide the same level of benefits. A recent Harvard study has identified the top five high-quality fruits and vegetables. Increasing intake of these can significantly lower the risk of chronic diseases.
In August 2024, a Harvard research team published a new study in The American Journal of Clinical Nutrition. This study utilized data from three large cohorts: the Health Professionals Follow-Up Study, the Nurses’ Health Study, and the Nurses’ Health Study II.
Researchers analyzed biomarkers from 41,714 participants and ranked 52 fruits and vegetables based on their metabolic quality by comparing their intake with 14 heart-metabolic biomarkers. The top five fruits and vegetables with the highest metabolic quality were: apples or pears, romaine lettuce, raw spinach, alfalfa sprouts, and eggplant or summer squash. Conversely, the bottom five were: peas or lima beans, French fries, watermelon, tomato juice, and corn. The study identified 19 fruits and vegetables as having high metabolic quality.
The research team then assessed the risk of major chronic diseases in 207,241 participants over 32 years. They found that a higher proportion of high metabolic quality fruits and vegetables in the total fruit and vegetable intake was associated with a lower risk of major chronic diseases. However, participants who consumed a high total amount of fruits and vegetables, but mostly those of medium or low metabolic quality, did not show a reduced risk of major chronic diseases and, in fact, had a higher risk of diabetes.
Specifically, among those with the lowest total fruit and vegetable intake, those with the highest proportion of high metabolic quality fruits and vegetables had a 15% lower risk of major chronic diseases compared to those with the lowest proportion. This trend was observed across different levels of total fruit and vegetable intake. Similar patterns were seen for atherosclerotic cardiovascular disease, type 2 diabetes, and chronic obstructive pulmonary disease, although cancer did not follow this pattern.
High-quality fruits and vegetables are rich in nutrients such as potassium, magnesium, β-carotene, flavonoids, and fruit fibers. These nutrients contribute to reducing the risk of chronic diseases through various protective mechanisms, including antioxidant and anti-inflammatory effects, and blood pressure reduction.
Apples and Pears Reduce Inflammation Markers
Apples and pears share similar nutritional profiles, containing various bioactive compounds such as flavonoids, dietary fiber, and antioxidants. These compounds are associated with a reduced risk of cardiovascular disease and related events.
A review study published in Current Developments in Nutrition in 2019 found that a higher intake of apples or pears, or a combination of both, significantly lowered the risk of cerebrovascular diseases, diabetes, cardiovascular diseases, and heart-metabolic disease mortality, as well as overall mortality risk.
Furthermore, a study published in The American Journal of Clinical Nutrition in 2021 observed that participants who consumed apples daily for six weeks showed a 17% reduction in fasting blood inflammatory biomarkers, with C-reactive protein decreasing by 17% and interleukin-6 by 12.4%. Additionally, the endotoxin biomarker lipopolysaccharide-binding protein (LBP) was reduced by 20.7%.
Spinach Benefits Brain Health
Spinach is rich in antioxidants, including quercetin and kaempferol, which are flavonoids. Research indicates that flavonoids can effectively prevent lipid peroxidation, a risk factor for atherosclerosis, diabetes, liver toxicity, and inflammation.
Spinach also supports brain health. It is high in lutein and zeaxanthin, two important carotenoids. A study published in the Journal of Alzheimer’s Disease found that patients with Alzheimer’s disease had about 50% lower levels of lutein and zeaxanthin in their brains compared to healthy individuals.
Eggplant Improves High Blood Pressure
Eggplant has been shown to improve blood pressure. A randomized, placebo-controlled study involving 100 participants found that consuming eggplant powder reduced diastolic blood pressure in those with elevated normal blood pressure and lowered both systolic and diastolic blood pressure in individuals with stage 1 hypertension. This suggests that eggplant can have varying effects on different types of hypertension.
Romaine Lettuce and Cooking Methods
Romaine Lettuce: Rich in polyphenols, carotenoids, and vitamin C, romaine lettuce helps protect cardiovascular health. Research shows that a diet including 20% lettuce improves lipid metabolism and plasma antioxidant capacity in rats, supporting heart health.
Cooking Methods: Cooking methods can affect nutritional value. For instance, frying potatoes significantly reduces their nutritional benefits and can increase the risk of high insulin levels and inflammation. Instead, consider healthier preparation methods like baking or boiling.
Spinach: Eating raw spinach maximizes lutein intake. For optimal nutrient extraction, use a blender or juicer, or add finely chopped spinach to salads or sandwiches.