Fruits and Vegetables Increase Plasma Carotenoids and Vitamins and Decrease Homocysteine in Humans

Abstract

Observational epidemiologic studies have shown that a high consumption of fruits and vegetables is associated with a decreased risk of chronic diseases. Little is known about the bioavailability of constituents from vegetables and fruits and the effect of these constituents on markers for disease risk. Currently, the recommendation is to increase intake of a mix of fruits and vegetables ("five a day"). We investigated the effect of this recommendation on plasma carotenoids, vitamins and homocysteine concentrations in a 4-wk dietary controlled, parallel intervention study. Male and female volunteers (n = 47) were allocated randomly to either a daily 500-g fruit and vegetable ("high") diet or a 100-g fruit and vegetable ("low") diet. Analyzed total carotenoid, vitamin C and folate concentrations of the daily high diet were 13.3 mg, 173 mg and 228.1 microg, respectively. The daily low diet contained 2.9 mg carotenoids, 65 mg vitamin C and 131.1 microg folate. Differences in final plasma levels between the high and low group were as follows: lutein, 46% [95% confidence interval (CI) 28-64]; beta-cryptoxanthin, 128% (98-159); lycopene, 22% (8-37); alpha-carotene, 121% (94-149); beta-carotene, 45% (28-62); and vitamin C, 64% (51-77) (P < 0.05). The high group had an 11% (-18 to -4) lower final plasma homocysteine and a 15% (0.8-30) higher plasma folate concentration compared with the low group (P < 0.05). This is the first trial to show that a mix of fruits and vegetables, with a moderate folate content, decreases plasma homocysteine concentrations in humans.

Six carotenoids in plasma used to assess recommended intake of fruits and vegetables in a controlled feeding study

“…Our findings are in accordance with two other published intervention studies that have used mixed fruit and vegetable diets Broekmans et al, 2000), although a direct comparison may be hampered by focus on different research questions and different length of interventions. The differences in the magnitude of relative response observed in the three studies could be explained by the difference in amounts and type of fruits and vegetables included in the high and low diets of these studies.…”

“…The proportion of carotenoid intake between the low and the high diet varied between the three studies. As an example, in the study by Broekmans et al (2000) the high diet contained 4.9 times more a-carotene than the low diet, whereas in the present study the difference in a-carotene content between the high and low diet was 2.5 times. The relative differences for b-carotene intake are similar in the three studies, and this is probably because b-carotene is present in a greater range of vegetables than a-carotene.…”

“…However, in a regular industrialized diet several different fruits and vegetables are usually eaten in varying amounts daily. Only a few fully controlled interventions have focused on how plasma concentrations carotenoids are affected by a mixed fruit and vegetable intake Broekmans et al, 2000).…”

Effects of enhanced consumption of fruit and vegetables on plasma antioxidant status and oxidative resistance of LDL in smokers supplemented with fish oil

“…Mean estimated folic acid intake also significantly increased in weeks 3-6. Deficiency of this nutrient has been linked to hyperhomocysteinaemia, an independent risk factor for coronary heart disease (Broekmans et al, 2000). Increased intakes of fruit and vegetables have been shown to decrease plasma homocysteine concentration although this was not measured in the present study.…”

Erratum to: Patients with mild hypertensive heart disease and left ventricular outflow tract obstruction: treatment with angiotensin II antagonists

“…However, as fruit consumption decreased, the effect of coffee on homocysteine became significant even when lower quantities of coffee were consumed (Table 4). It has been suggested that at least 5 servings of fruits and vegetables a day are necessary in order to observe a decrease in homocysteine levels, 15,16 and this agrees with our findings. It has been suggested that this protective effect of fruit against the homocysteine-raising effect of coffee could be due to folic acid that may affect the homocysteine concentration.…”