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Guava

Psidium guajava

Fruits. Latin American & Amazon, Caribbean, African and Pacific & Southeast Asia.

Also called Common guava, Guayaba, Goiaba, Bayabas

Pinyin: fān shí liú

Spanish: Guayaba

Leaf tea may lower sugar

Guava is a tropical fruit with a sweet, musky smell, and its leaves are brewed as a folk tea. The fruit is one of the richest food sources of vitamin C.

Did you know? Guava is one of the richest fruit sources of vitamin C, with several times the amount found in an orange by weight.

What it may help, and how strong the proof is

Blood sugar. A 2026 review found four small randomized trials of guava fruit or leaf that measured blood sugar among other outcomes. The trials were short and small, so results are not firm. Larger trials are needed.See the research: 6 studies in people
Promising proof
Colds, flu & immunity. The fruit is very high in vitamin C, which the body needs for normal immune function. Trials of the fruit for colds are lacking.See the research: 2 studies in people
Traditional proof
Digestion & gut health. Used in folk medicine for diarrhea in India, China and Latin America. A few small studies in children have been run, but their quality is unclear and good trials are lacking.See the research: 5 studies in people
Traditional proof

Parts of the body

Pancreas & blood sugar, Immune system, Gut & intestines, Stomach

Traditional use

Folk healers in Latin America, the Caribbean, Africa and parts of Asia brewed guava leaves as tea for diarrhea and stomach upset. Fruit and leaves are part of everyday cooking in many tropical countries.

How it is classified

Herbal actions: Nutritive, Astringent, Antioxidant. Energy: neutral.

How people take it

Eat the fruit fresh or as juice, or drink leaf tea. Leaf extract capsules are also sold. Studies of leaf tea have used varied amounts, and no standard dose has been proven for blood sugar.

Food, tea, juice and capsule.

Where to get it

A small tree grown across tropical and subtropical regions of Latin America, the Caribbean, Africa, Asia and the Pacific. Fresh fruit is sold in markets, dried leaf is sold as tea, and leaf extract is sold as capsules.

Be careful

Guava fruit is safe for most people as food. Large amounts of seed-heavy fruit may upset the stomach. Leaf tea may lower blood sugar, so check with a doctor if you take diabetes medicine. Little is known about leaf tea and extracts in pregnancy, so talk with a clinician first.

Avoid if: pregnancy; diabetes medicines; low blood sugar.

Mixing with other things

Use caution
Diabetes medicine (metformin, insulin, glipizide, Ozempic)
Leaf tea may lower blood sugar and add to diabetes medicines, raising the risk of lows.
Worth knowing
Blood pressure medicine (lisinopril, amlodipine, losartan)
Guava leaf has been tested for blood pressure in animals and in a few small human studies, with no firm result. Check with a doctor if you take blood pressure medicine.

Adds up with others that may lower blood sugar: , , , , , , , , , , , , , and 54 more.

The honest take

Guava is a real food with a lot of vitamin C, and that part is well established. The leaf tea has only a few small human trials, with mixed results, and its use for diarrhea rests on tradition. Eat the fruit freely, but check with a doctor before using leaf tea or extracts if you have diabetes.

Sources

Each “See the research” link opens PubMed, the U.S. National Library of Medicine's index of medical studies, showing only trials and reviews done in people. The number tells you how much a use has been tested, not whether it worked. The proof rating tells you that.

Study counts checked October 2026.