Dietary onion intake as part of a typical high fat diet improves indices of cardiovascular health using the mixed sex pig model.

The aim of this study was to evaluate the potential health benefits of onions consumed at two levels of intake, using the pig model. The dietary fat content was set at a level typical of a "western" diet (25% w/w). Fifteen female and fifteen male pigs (Large White x Landrace) were allocated to one of three dietary treatments in a randomised block design. Treatments consisted of control diet (no onion) and onion supplementation at either 8.6 or 21.4 g of onion/MJ DE fed for six weeks. Onion consumption reduced plasma triglyceride levels by 15% (P=0.030) regardless of sex and onion dose. Total plasma cholesterol and cholesterol fractions were unaffected by onion supplementation (P>0.050). The bioactivity of onion was evident in haematocrit measures, where red blood cell and haemoglobin were significantly reduced in a dose dependant manner (P<0.001 and P=0.011, respectively), while other cell counts, with exception of segmented neutrophils (-18%, P=0.012), were largely unaffected. Serum oxidative status was improved (P=0.007) in pigs consuming onions. These data demonstrate that consumption of onions can have positive health effects in both male and female pigs consuming a high fat diet.

Consumption of brown onions (Allium cepa var. cavalier and var. destiny) moderately modulates blood lipids, haematological and haemostatic variables in healthy pigs.

Although garlic and onions have long been associated with putative cardiovascular health benefits, the effects of different commercially available onions and level of intake have not been studied. Therefore, the aim of the present study was to evaluate the potential health benefits of raw onions using the pig as a biomedical model. Twenty-five female (Large White x Landrace) pigs were used in a (2 x 2)+1 factorial experiment. Pigs were fed a standard grower diet supplemented with 100 g tallow/kg with the addition of Allium cepa var. cavalier or var. destiny at 0, 10 or 25 g/MJ digestible energy for 6 weeks. Overall, the consumption of onions resulted in significant reductions in plasma triacylglycerol; however, the reductions were most pronounced in pigs fed destiny onions (-26 %, P=0.042). 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 and Hb levels, while the white blood cell concentrations, particularly lymphocytes, were increased in pigs that consumed onions. Furthermore, indices of blood clotting were largely unaffected by onion consumption. In conclusion, dietary supplementation with raw brown onions has moderate lipid-modulating and immunostimulatory properties. However, daily onion intake >25 g/MJ digestible energy could be detrimental to erythrocyte numbers.