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.