Serum vitamins and fruit and vegetable intake

Daucher et al , 20008, Relationships between different types of fruit and vegetable consumption and serum concentrations of antioxidant vitamins Brit Journal of Nutrition vol 100, 633-641

There is evidence of an inverse relationship between fruit and vegetable consumption and health . Many countries now recommend the consumption of at least five portion of fruits and vegetables (400 g) per day. Several mechanisms have been proposed to explain this positive association, including the increased intake of antioxidant compounds that are widely found in fruits and vegetables. Yet trials in which antioxidant micronutrients were taken at high doses over long periods have not confirmed a potential beneficial effect and even suggested harmful effects.

This study looks at the effect of different types of fruits and vegetables on serum vitamin antioxidant levels would be useful. Blood samples from 3521 subject (1487 men and 2034 women), aged 35-60 years participants were analysed for l3-carotene, vitamin C and a-tocopherol and completed at least six dietary records during the first 2 years of the study. Women had higher mean l3-carotene and vitamin C serum concentrations than men, but lower a-tocopherol serum concentration. Serum l3-carotene and vitamin C concentrations were positively correlated with consumption of both fruit and vegetable, as well as with most of the fruit and vegetable groups tested. These relationship persisted after adjustment for confounding factors. Regression analysis showed a linear dose-response relation hip. Root vegetables and citrus fruits were particularly associated with l3-carotene serum status as were citrus fruits for vitamin C. Fruit and vegetable consumption was either not or weakly associated with a-tocopherol serum concentrations.

The authors conclude that the association between fruit and vegetable intake were too weak to allow serum concentrations to be used as a measure of fruit and vegetable intake.

Martin Eastwood
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