Ingestion of a high-fat meal impairs flow-mediated vasodilation of the brachial artery for at least 4 h; however, co-ingestion of vitamin antioxidants or a green salad has been shown to prevent this effect. Flow-mediated brachial artery reactivity test (BART) both before and 3 h after a 900 calorie 50 g fat meal was evaluated in 38 healthy volunteers. Subjects were randomised to 4 weeks of daily supplementation with a powdered fruit vegetable juice concentrate (Juice Plus) along with a complex supplement providing nutritional antioxidants and various herbal extracts (Vineyard), Juice Plus alone, or a matching placebo. At 3 weeks and 4 weeks, BART was repeated both before and after the high-fat meal. Serum nitrate/nitrite concentrations were measured at baseline and at 4 weeks. Four weeks of the Juice Plus–Vineyard combination blunted the detrimental effect of the high-fat meal. Four weeks of Juice Plus alone had a similar beneficial effect, whereas there was no substantial effect of the placebo. In the subjects treated with supplements, concentrations of serum nitrate/nitrite increased from 78 ± 39 to 114 ± 62 μmol/l. The authors concluded that daily ingestion of modest amounts of a fruit/vegetable juice concentrate with or without adjunctive phytonutrient supplementation can reduce the immediate adverse impact of high-fat meals on flow-mediated vasoactivity and increase nitrate/nitrite blood concentration.