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Red Onions: A Weapon Against Heart Disease?

People are often confused by conflicting information in health-related stories in the press. What on one day is the latest breakthrough in health may be highlighted as harmful two weeks later. This creates concerns and questions about how to eat properly for long-term health, while managing everyday challenges such as children’s eating habits or the stresses of modern-day living. To help you through this maze, this column will take a topic reported in the press or published in a book and examine it. Sometimes we may agree, while other times we will document concerns. Either way, we hope you find this useful and interesting.

A recent headline in the British Daily Mail online read, “The humble red onion could be the answer to reducing bad cholesterol.” The article stated that researchers at the Chinese University of Hong Kong found red onion helps lower bad cholesterol while retaining the body’s levels of good cholesterol. The research was carried out on hamsters that had been put on a high-cholesterol diet and were then fed crushed raw red onion for eight weeks. Cholesterol measurements showed that low-density lipids (LDL), or “bad” cholesterol, were reduced in the animals by an average of 20 percent, while high-density lipid (HDL) or “good” cholesterol levels stayed the same. LDL cholesterol is implicated in the narrowing of arteries that can cause heart attacks; HDL cholesterol is associated with healthy hearts.

Results from animal experiments are not automatically true for humans, and research needs to be carried out with humans to validate these preliminary findings. To date, studies linking onion consumption to specific conditions tend to focus on cancer rather than on cholesterol levels.

However, some human studies indicate that onions are heart-healthy, and the benefits attributed to eating onions are extensive. Their pungent smell is due to sulfur-containing compounds, which help the detoxification process in the liver. They are thought to help prevent heart attacks and strokes due to their effect of making blood less sticky and thus less liable to clot. Onions are high in a variety of phytonutrients – substances in plants that provide health benefits – including quercetin and rutin.

Quercetin is a powerful antioxidant, anti-inflammatory, antihistamine, antibacterial and possible anti-cancer agent. Rutin helps strengthen capillaries and thins the blood, both of which improve circulation. These substances strengthen immunity as they “feed” the good bacteria in your gut that aid the body’s natural defenses. Onions also may be a good source of chromium (depending on soil quality), which supports insulin function and can thus influence blood sugar levels. Lastly, a relatively new study reports that regular consumption of onions can improve bone density in older women.

Overall, the evidence points to onions being a beneficial addition to your diet. When preparing them, do not overpeel, as nutrients are concentrated in the outer layers. Use immediately after chopping, be generous with portion sizes, and remember that cooking reduces the health benefits. Try adding raw red onion to salads and dips. If you can’t bear the thought of raw onion, cook it slowly over low heat.n

Sources: “Super Foods Super Fast,” by Michael van Straten and Barbara Griggs; National Center for Biotechnology Information (; American Journal of Physiology (; British Medical Journal (

Julie Godfrey is a nutritional therapy practitioner and a full member of the British Association of Applied Nutrition and Nutritional Therapy (BANT). For information, see

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