What it does, and how sure we are
Garlic's effects trace to allicin and its sulfur cousins. Unusually for a kitchen ingredient, one benefit is genuinely well-evidenced in people.
- Lowers blood pressureStrong · trials
- Modestly improves cholesterolEmerging
- May reduce colds' frequency & lengthEmerging
- "A natural antibiotic that cures infection"Not supported
Meta-analyses of trials show garlic gives a real, if modest, drop in blood pressure, most in people who are hypertensive, which is why this is one of our few Strong ingredient ratings. Allicin is a powerful antimicrobial in a test tube, but that does not mean eating garlic treats an infection in the body.
The one thing to know
A whole garlic clove barely smells. Its active compound, allicin, is made on demand: crushing or chopping breaks cells so an enzyme meets a precursor and, over about ten minutes, produces allicin. And that enzyme is fragile, heat destroys it. So the worst thing you can do is crush garlic and throw it straight into hot oil. Crush it, let it rest, then cook.
Crushed, then rested
full allicin
Ten minutes between crushing and heat lets the allicin form, so it survives the cooking that follows.
Straight into hot oil
far less
Immediate heat kills the enzyme before it works, so you get garlic flavour but much less of the compound.
How to cook with it
Garlic is a base, a finish and a flavour in its own right. The one rule that always applies: it burns easily, and burnt garlic is bitter.
Ginger-garlic paste
Pounded with ginger, it is the aromatic foundation of countless curries.
Add it after the onions
Garlic scorches faster than onion. Add it once the onions have softened, and keep the heat in check.
Crush and wait
Prep the garlic first, then the rest, so it has its ten minutes before it hits the pan.
Raw for punch
A little raw garlic in chutney or a tempering at the end keeps the most bite, and the most allicin.
Traditional use
Garlic is one of the oldest home remedies there is, taken raw with honey for coughs and colds, and long regarded as a warming tonic for the heart and circulation. On the cardiovascular front, tradition and modern trials happen to agree; on curing infection, they do not. We label each claim by its own evidence.
Is it safe?
As a food, yes, and enjoyed widely. A few honest notes: large amounts of raw garlic can cause heartburn, wind or a burning mouth, and it famously lingers on the breath and skin. Because it has a mild blood-thinning effect, people on anticoagulants or heading into surgery should mention high-dose garlic supplements to a clinician. In normal cooking, it is simply good, useful food.
Sources
- Ried K. Garlic lowers blood pressure in hypertensive individuals, regulates serum cholesterol, and stimulates immunity: an updated meta-analysis and review. J Nutr. 2016;146(2):389S–396S.
- Lissiman E, Bhasale AL, Cohen M. Garlic for the common cold. Cochrane Database Syst Rev. 2014;(11):CD006206.
- Bayan L, Koulivand PH, Gorji A. Garlic: a review of potential therapeutic effects. Avicenna J Phytomed. 2014;4(1):1–14.