Fruits and vegetables, foods rich in flavonoids and antioxidants, have been associated with lower risk of stroke, coronary heart disease, and markers of inflammation and oxidative stress in adults. Markers of inflammation and oxidative stress are predictors of coronary heart disease risk; however, it is unknown whether these markers are related to dietary flavonoid and antioxidant intake in youth.
To determine whether greater intakes of fruit and vegetables, antioxidants, folate, and total flavonoids were inversely associated with markers of inflammation and oxidative stress in 285 adolescent boys and girls aged 13-17 years.
In this cross-sectional study conducted between February, 1996-January, 2000, diet was assessed by a 127-item food frequency questionnaire. Height and weight measurements were obtained and a fasting blood sample drawn. Spearman partial correlation analyses evaluated the relation of intakes of fruit and vegetables, antioxidants, folate, and flavonoids with markers of inflammation (C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and 15-keto-dihydro-PGF2α metabolite and oxidative stress (urinary 8-iso prostaglandin F2α, a F2-isoprostane), adjusting for age, sex, race, Tanner stage, energy intake, and body mass index.
Urinary F2-isoprostane was inversely correlated with intakes of total fruit and vegetables, vitamin C, beta-carotene, and flavonoids. Serum CRP was significantly inversely associated with intakes of fruit, (r = -0.19; p=0.004), vitamin C (r = -0.13, p=0.03); and folate (r=-0.18; p=0.004). Serum IL-6 was inversely associated with intakes of legumes, vegetables, beta-carotene, and vitamin C (r= -0.12, p=0.03). Serum TNF-α was inversely associated with beta-carotene (r=-0.16, p=0.02) and luteolin (r= -0.15, p=0.02).
Study results show that the beneficial effects of fruit and vegetable intake on markers of inflammation and oxidative stress are already present by early adolescence and provide support for the United States Dietary Guideline “to consume five or more servings per day” of fruits and vegetables to promote beneficial cardiovascular health