To examine the associations of food consumption, serum vitamins and metabolic syndrome risk with physical activity level in middle-aged adults.

Cross-sectional.

National Health and Nutrition Examination Survey (NHANES) 2005–2006.

Adults aged 40–70 years were divided into three groups by tertile of accelerometer-determined steps/d (in men and women, respectively): tertile 1 (sedentary), <6802, <5785; tertile 2 (intermediate), 6802–10698, 5785–9225; tertile 3 (active), ≥10699, ≥9226.

The active men consumed more grain products, fruits and vegetables, whereas the active women consumed more legumes and vegetables, compared with the sedentary group. Serum vitamin concentrations were associated with daily steps in both men and women. Vitamin C, α-carotene, trans-β-carotene, cis-β-carotene, β-cryptoxanthin, lutein+zeaxanthin, lycopene, γ-tocopherol and vitamin D were significantly associated with daily steps. OR (P<0·05) for the sedentary group were 1·52 and 1·61 for low HDL cholesterol, 1·66 and 3·97 for hypertriacylglycerolaemia, 1·02 and 2·73 for abdominal obesity, 1·79 and 1·77 for hyperglycaemia, 1·59 and 1·60 for hypertension, and 1·85 and 2·47 for metabolic syndrome in men and women, respectively.

Those with the highest steps taken showed a more healthful eating profile and a better serum vitamin profile compared with less active adults. Those with the lowest steps taken had greater odds of having metabolic syndrome and its risk components. Probably, daily walking is a marker of a healthful eating profile and increasing daily walking is one of the healthful ways to decrease the metabolic syndrome and its risk components.