The benefits to the heart of garlic and onions has long been recognised, but the effects of different onions available commercially and the doses required had not yet been studied, said the researchers at the Victorian Institute of Animal Science in Australia.
Using pigs, the scientists studied the functional properties of two onion cultivars grown in different environments and agronomic conditions.
Twenty-five female (Large White x Landrace) pigs were used for for the experiment and they were fed a standard grower diet supplemented with 100 g tallow/kg with the addition of Allium cepa variety cavalier or variety destiny at 0, 10 or 25 g/MJ digestible energy for six weeks.
The researchers report that overall, the consumption of onions resulted in significant reductions in plasma triacylglycerol with the reductions most pronounced in pigs fed destiny onions. But total plasma cholesterol and LDL:HDL ratios were not significantly different.
'Onion supplementation, regardless of the variety, resulted in dose-dependent reductions in erythrocyte counts, while the white blood cell concentrations, particularly lymphocytes, were increased in pigs that consumed onions,' write the authors of the study, concluding that daily onion intake of more than 25 g/MJ digestible energy could be detrimental to erythrocyte numbers.
In addition, according to the study findings, published in the February 2004 issue of the British Journal of Nutrition, blood clotting was largely unaffected by onion consumption.
The paper, 'Consumption of brown onions (Allium cepa var. cavalier and var. destiny) moderately modulates blood lipids, haematological and haemostatic variables in healthy pigs,' by E. Ostrowska, N. K. Gabler, S. J. Sterling, B. G. Tatham, R. B. Jones, D. R. Eagling, M. Jois and F. R. Dunshea was published in the British Journal of Nutrition (2004) 91:211-218.