Foods that can prevent
diseases are being highly researched in the recent years. Onion is an important
ingredient in the cuisine world wide and the demand for onions has seen an
upward trend in the last three decades. This food is known for its many health
benefits including 'anti-platelet activity, anti-microbial activity,
anti-inflammatory and anti-asthmatic effects', according to nutritionists.
Although a lot of anti-platelet drugs are available in the market, using onions
as an alternative would be a healthier, safer option, and a boon to patients
suffering from thrombosis.
Thrombosis is basically
a disease wherein the blood platelets clot together, either due to some genetic
factor, or due to the presence of some auto-immune disease, making the patient
more vulnerable to strokes, heart attacks and many other potentially
Raw onions are blessed
with the ability to prevent platelet aggregation (clumping together of blood
platelets), but when steamed they lose their ability to do so, found Emilie
Hansen at the Department of Health Professions, Metropolitan State University
of Denver, Denver, USA and her colleagues, in this study.
The main objective of
this study was to examine how cooking affected the antiplatelet activity of
onion in multiple human blood donors. They also studied the polyphenol
concentration and change in soluble solids after cooking of onions.
Onions were quartered
and steamed for 0, 1, 3, 6, 10 and 15 minutes respectively and using in vitro
blood aggregometry, their efficiency at exhibiting anti-platelet activity was
tested. The results showed that the onions
steamed for 3 and 6 minutes demonstrated low or no anti-platelet activity
However, anti-platelet activities of onions were reversed at after 10 minutes
of steaming, and the onions actually stimulated platelet activity and
encouraged possible thrombus formation.
It was thus, concluded
that onions managed to retain their
anti-platelet activity only till a few minutes of cooking.
suffering from thrombosis should consider consuming raw onions than cooked
concentration and total dissolved solids content were, however, not affected by
The researchers thus
suggested that in order to preserve the antiplatelet activity of onions,
cooking time of onions must be minimized and preferably raw onions may be
consumed on a regular basis.
rapidly destroys and reverses onion-induced antiplatelet activity; Emilie
Hansen et al; BMC Nutrition Journal 2012