Onions- A Global Benefit to Health
Gareth Griffiths, Laurence Trueman, Timothy Crowther, Brian Tomas and Brian Smith
Onion FAQ.
• Bulb onions likely originated in central Asia, but are not found in the wild.
• Onions are grown in every part of the world where plants are farmed.
• Onion is the second most important horticultural crop world wide.
Two Chemical Classes With Perceived Health Benefits.
Flavonoids:-Anthocyanins (Red) -Quercetins (Yellow)
Alkyl cysteine sulphoxides (ACSOs):-Flavor precursors cleaved by alliinase enzyme
ACSOs and Associated Breakdown Products
• Three ACSOs are present in intact onion tissue.
• Upon hydrolysation by alliinase, and subsequent spontaneous reactions with each other and nearby compounds, ACSOs give rise to ~50 sulphur containing compounds.
• This wide array of sulphur containing compounds contribute to onion flavor and are reported to provide benefits to human health.
Factors Affecting final composition of ACSO breakdown products.
• Initial concentration and ratios of the three ACSO species.
• Availability of alliinase enzyme (tissue disruption).
• Type and concentration of other compounds in the environment with witch ACSO breakdown products react.
• pH & temperature of the environment.
ACSO Breakdown
Reported Health Benefits of ACSO breakdown products in Onion
• Anticancer activity through modulation of enzymes involved in metabolization of carcinogenic compounds.
• Possible lowering of serum cholesterol.
• Lowering systolic blood pressure & thinning the blood (only compounds found in uncooked pungent cultivars).
• Antiasthmatic activity, suppressing reactions leading to bronchial restriction.
• Antifungal and antibacterial properties.
Flavonoid Compounds in Onion
Flavonols:• Yellow compounds concentrated in the skin of
the onion.• Sixteen flavonol compounds have been
identified in onion.
Anthocyanins:• Red compounds.• Four anthocyanin compounds have been
identified in onion.
Reported Health Benefits of Flavonoids in Onion
• Antioxidant effects of flavonoids help to protect cells from oxidative stress resulting from free radical damage, as well as reducing cancer rates by protecting DNA from oxidative damage.
• Possible lowering of serum cholesterol by quercetin compounds.
• Phenolic flavonoid compounds may provide some antibiotic activity.
Garlic as an Antioxidant: The Good The Bad and The Ugly
S.K. Banerjee, Pulok K. Mukherjee and S.K. Maulik
Garlic Health FAQ.
• Garlic has played an important dietary and medicinal role for centuries.
• The sale of medicinal garlic preparations is on par with that of many prescription drugs.
• A wide array of health claims are made for garlic and its various preparations.
Health Benefits Attributed to Garlic
• Prevention of Cardiovascular disease.
• Reduced Cancer Risk.
• Treatment of microbial infections.
• Antidote for heave metal poisoning.
• Hepatoprotective.
Garlic and Human Health
• Garlic consumption has been recognized in reducing rates of cancer and Cardiovascular disease.
• This effect is thought to be largely due to the antioxidant properties of the many organosulphur compounds found in garlic preparations.
Various Garlic Preparations Examined for Health Effects.
• Raw Garlic
• Heat Treated Garlic
• Garlic Powder
• Aged garlic Extract
• Garlic Oil (steam distilled, oil macerated, ether extract)
• Garlic Protein
Garlic preparation method, effects on various oxidative stress conditions.
Garlic Organosulphur Compounds
• When Garlic is crushed Allinase enzyme acts on Alliin to form allicin.
• Allicin has both antioxidant and oxidative properties.
• The many breakdown products of Allicin vary across different preparation methods.
• Different garlic preparations are reported to have varying antioxidant and disease fighting properties.
Garlic Organosulphur Compounds
Garlic Organosulphur Compounds Reported Effects.
• Antioxidant (free radical scavenging) protecting DNA, Proteins, Lipids, and other compounds from oxidative damage.
• Increased endothilial cell NO production, making blood vessels more elastic.
• Decreased hepatic cytochrome P450, protecting the liver from toxin (acetominophen) induced injury.
Negative Effects Resulting From large Doses of Garlic.
• Bad Breath
• Anemia.
• Weight loss.
• Lysis of red blood cells.
• Altered cellular architecture in the heart, liver and kidneys.