Proceedings of the Nutrition Society

Symposium on ‘Phytochemicals’

Biological effects of fruit and vegetables

Lars O. Dragsteda1a2 c1, Britta Kratha1, Gitte Ravn-Harena1, Ulla B. Vogela3, Anne Marie Vinggaard, Per Bo Jensena1, Steffen Lofta2, Salka E. Rasmussena1, The late BrittMarie Sandstroma4 and Anette Pedersena4

a1 Danish Institute for Food and Veterinary Research, Soborg, Denmark

a2 Department of Public Health, Panum Institute, University of Copenhagen, Copenhagen, Denmark

a3 National Institute of Occupational Health, Copenhagen, Denmark

a4 Research Department of Human Nutrition and Center for Advanced Food Studies, Royal Veterinary and Agricultural University, Frederiksberg, Denmark

Abstract

A strong and persistent effect of plant-derived foods on the prevention of lifestyle diseases has emerged from observational studies. Several groups of constituents in plants have been identified as potentially health promoting in animal studies, including cholesterol-lowering factors, antioxidants, enzyme inducers, apoptosis inducers etc. In human intervention studies the dose levels achieved tend to be lower than the levels found to be effective in animals and sampling from target organs is often not possible. A controlled dietary human intervention study was performed with forty-three volunteers, providing 600 g fruit and vegetables/d or in the controls a carbohydrate-rich drink to balance energy intake. Surrogate markers of oxidative damage to DNA, protein and lipids, enzymic defence and lipid metabolism were determined in blood and urine. It was found that a high intake of fruit and vegetables tends to increase the stability of lipids towards oxidative damage. Markers of oxidative enzymes indicate a steady increase in glutathione peroxidase (GPX1) activity in erythrocytes during intervention with fruit and vegetables but there is no effect on GPX1 transcription levels in leucocytes. No change occurs in glutathione-conjugating or -reducing enzyme activities in erythrocytes or plasma, and there are no effects on the transcription of genes involved in phase 2 enzyme induction or DNA repair in leucocytes. Fruit and vegetable intake decreases the level of total cholesterol and LDL-cholesterol, but does not affect sex hormones. In conclusion, it has been shown that total cholesterol and LDL-cholesterol, markers of peripheral lipid oxidation, and erythrocyte GPX1 activity are affected by high intakes of fruit and vegetables. This finding provides support for a protective role of dietary fruit and vegetables against CVD.

Correspondence:

c1 *Corresponding author: Professor Lars Dragsted, fax +45 2144 7699, email lod@dfvf.dk