Sudu Lunu (Allium sativum): Garlic, the Kitchen Medicine With 80 Clinical Trials

Sudu lunu (Allium sativum) is the rare traditional medicine that modern science has tested to exhaustion and largely vindicated. Garlic has more randomised clinical trials behind it than almost any other plant on this website, and by 2025 the meta-analyses agree on a modest but real conclusion: it lowers blood pressure a little, lowers cholesterol a little, and the effect is dose-dependent. In the Sri Lankan kitchen it never needed the proof; no curry, sambola or tempered dhal is complete without it.

Botanical and Cultural Background

Garlic is a bulbous perennial of the onion family, grown in Sri Lanka's cooler up-country districts and imported in bulk from India and China. Each bulb divides into cloves; the pungency arises only when a clove is cut or crushed, which lets the enzyme alliinase convert alliin into allicin, the sulphur compound responsible for the smell and most of the medicinal activity. Every Ayurvedic text lists garlic (lasuna) as a heating, cleansing rasayana, and village practice uses it for everything from ear pain to worms.

Traditional Uses in Sri Lankan Medicine

• Colds and chest congestion — crushed cloves in hot water, coriander tea, or warmed garlic oil rubbed on the chest.
• Digestion and worms — raw cloves with a little bee honey before breakfast.
• Joint and ear pain — garlic warmed in coconut oil, applied externally or as ear drops.
• Heart health — daily raw garlic for "blood thickness", an intuition modern trials support.

What the Research Shows

The trial record is deep. An updated meta-analysis found garlic lowered systolic blood pressure by roughly 8–9 mmHg in hypertensive people, comparable to a low dose of standard medication, and reduced total cholesterol in those with raised levels (Ried, 2016). A 2023 meta-analysis of randomised trials in BMC Complementary Medicine and Therapies confirmed improvements across components of metabolic syndrome, including blood pressure, triglycerides and fasting glucose. A 2025 dose-response meta-analysis of 19 trials of aged garlic extract in Phytotherapy Research reported smaller but consistent effects — about 2.5 mmHg systolic and 4.4 mg/dL LDL — and a 2025 Frontiers in Nutrition analysis judged long-term garlic supplementation safe as an add-on for hypertension. The immune-stimulating and antimicrobial effects seen in the laboratory are real but less well quantified in people.

Evidence updated September 2026.

How Sudu Lunu Is Prepared

For medicinal effect, crush or chop a clove and let it stand ten minutes before eating or cooking, which maximises allicin. One to two raw cloves a day is the traditional dose; garlic tempered in oil at the end of cooking keeps more benefit than garlic boiled for an hour. For a cold, crush two cloves into a cup of hot koththamalli (coriander) tea with a spoon of bee honey.

Safety and Precautions

Garlic mildly thins the blood: people on warfarin, aspirin or other anticoagulants, and anyone facing surgery within two weeks, should limit medicinal doses and inform their doctor. Large raw amounts can cause heartburn and stomach upset. Culinary use is safe in pregnancy; concentrated supplements are best avoided without advice. And garlic supplements do not replace blood-pressure medication — they are an addition to it.