Steam Cooking Destroys the Anti-Platelet Activity of Onions

Onion inhibits the blood platelets from clogging together and forming a thrombus, which may be harmful to the human body. Steam cooking, on the other hand, reverses this action of the onion.

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 life-threatening diseases.

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A blood clot (thrombus) in the deep venous system of the leg leads to deep vein thrombosis (DVT). DVT is a major cause of morbidity and mortality.

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. Patients suffering from thrombosis should consider consuming raw onions than cooked ones.

Total polyphenolic concentration and total dissolved solids content were, however, not affected by steaming time.

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.

Reference: Steam-cooking rapidly destroys and reverses onion-induced antiplatelet activity; Emilie Hansen et al; BMC Nutrition Journal 2012

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Source-Medindia