Does aged garlic extract work?
A little, if your blood pressure is high. Trials found garlic pills cut the top number by 8 to 9 points. But there isn’t enough evidence they prevent heart attacks or strokes.
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Does aged garlic extract work?
A little, and mostly if your blood pressure is already high. Across 12 trials in 553 people with high blood pressure, garlic pills cut the top number by an average of 8.3 points (mmHg).
A separate review of 9 trials found a fall of about 9 points. But it said the trials were small and the evidence is not strong.
So think of it as a small step down. A top number of 150 might drop to about 142. That’s still above the NHS line for high blood pressure, which is 140/90 or higher when a health worker checks it.
| Claim | What trials found | How sure |
|---|---|---|
| Lower blood pressure | 8 to 9 points off the top number, in people with high blood pressure. | Small trials. The evidence is not strong. |
| Lower cholesterol | About 8% off total cholesterol, if it was raised and garlic was taken for over 2 months. | A small effect, says the US NIH. |
| Lower blood sugar | May fall a little in people with diabetes. | A small effect, says the US NIH. |
| Fewer colds | One trial of 146 people: 24 colds on garlic, 65 on dummy pills. | Not enough evidence, says Cochrane. |
| Fewer heart attacks or strokes | Not shown. | Not enough evidence, says Cochrane. |
Sources: Ried 2020; Rohner 2015; Ried 2013; NCCIH; Cochrane: colds; Cochrane: heart
Don’t know your number? Start there. See what your blood pressure reading means.
What is aged garlic extract?
It’s garlic left to age for about 20 months at room temperature. Ageing turns allicin, the sharp part of raw garlic, into steadier compounds. The main one is called SAC (S-allylcysteine).
Steady compounds mean each capsule can hold the same measured amount. Both trials below used the same brand.
| Daily dose | Trial | Top number, compared with dummy pills |
|---|---|---|
| 240 mg (1 capsule) | 79 people whose blood pressure wasn’t under control, despite medicines | No clear difference. |
| 480 mg (2 capsules) | Same trial | Fell 11.8 points more. |
| 960 mg (4 capsules) | Same trial | Fell 7.4 points at 8 weeks. Could have been chance. |
| 1.2 g (2 capsules) | 88 people whose blood pressure wasn’t under control | Fell 5 points more, on average. |
Sources: Ried 2013, dose trial; Ried 2016, AGE at Heart
One research group ran both trials. The maker funded the larger one, and another firm supplied the capsules for the dose trial.
So treat 11.8 as the best case. In the larger trial, the average fall was 5. If you buy a pack, check it gives the dose in mg, so you can compare it with the table.
Does garlic prevent heart attacks or strokes?
Nobody knows. That’s the missing proof behind every garlic claim. A Cochrane review found just 2 trials, with 87 people between them.
That’s not enough to tell if garlic cuts heart attacks, strokes or deaths. The review also said the blood pressure falls in those trials were within normal reading-to-reading change.
So garlic isn’t a swap for blood pressure tablets. Never stop or change a prescribed medicine without your prescriber.
The NHS says lowering your blood pressure even a small amount can help cut your risk. Its own list is all habits.
Six NHS changes that help lower blood pressure
- Eat a healthy, balanced diet.
- Aim for at least 150 minutes of exercise a week.
- Lose weight if you’re overweight.
- Avoid salty food and adding salt to your meals.
- Avoid drinking more than 14 units of alcohol a week on a regular basis.
- Don’t smoke, and go easy on caffeine from coffee, tea and cola.
Source: NHS: high blood pressure
For how much exercise moves the number, see exercise and blood pressure.
Do garlic tablets lower cholesterol?
A little, if yours is raised. A review of 39 trials found garlic cut total cholesterol by about 8% in people with high cholesterol. That was only when they took it for more than 2 months.
Picture a total of 6. An 8% cut takes it to about 5.5.
LDL, the main bad cholesterol, fell too. Good HDL rose only slightly, and triglycerides, another blood fat, didn’t clearly change. The same research group led this review.
For other ways to bring it down, see how to lower cholesterol.
Are garlic supplements safe?
Mostly, yes. Garlic by mouth has been used safely in studies lasting up to 7 years.
Side effects include bad breath and body smell, tummy pain, wind and feeling sick. Some people are allergic to garlic.
Aged garlic isn’t free of side effects either. In one trial, about 40% of people had minor ones such as reflux (acid coming back up) and burping. So did about 40% on dummy pills.
The bigger risk is bleeding. Garlic pills may raise your risk of bleeding.
Before you take garlic capsules
- On warfarin, another blood thinner or aspirin? Talk to your doctor before you start.
- Having surgery? Tell your care team you take garlic pills.
- Already on any medicine, even one bought without a prescription? Check with a pharmacist first.
- Pregnant or breastfeeding? Stick to the amounts of garlic found in food.
- Have kidney or liver problems? The NHS says don’t take herbal medicines.
- Don’t give herbal medicines to children. Not enough is known about their safety.
Sources: NCCIH; NHS: herbal medicines; NHS: warfarin
Other medicines that may not mix with herbal ones include statins (for cholesterol), antidepressants, metformin (for diabetes), ramipril (for blood pressure) and the combined pill.
Weighing up other pills too? See which supplements are worth taking.
When to speak to a GP
High blood pressure does not usually cause symptoms. Get help if:
- You’re 40 or over and haven’t had your blood pressure checked for more than 5 years. You can get it checked at a pharmacy or GP surgery. Some pharmacies may charge.
- Your readings are high: 140/90 or higher when a health worker checks, or 135/85 or higher at home.
- You take warfarin, another blood thinner or aspirin and want to try garlic pills.
- You often have headaches or blurred vision, chest pain that comes and goes, or other symptoms you’re worried could be caused by high blood pressure. Get help from NHS 111.
- You get sudden chest pain that doesn’t go away. It can feel like squeezing, pressure, burning or indigestion. Or pain that spreads to your arm, neck, jaw, stomach or back, or chest pain with sweating, feeling sick, light-headed or short of breath. Call 999.
Checking at home? See how to measure blood pressure at home.