Indications
Catechins are natural plant antioxidants found mainly in green tea, and also in cocoa, apples and grapes. The best known is EGCG (epigallocatechin gallate). Green tea catechin extracts are included in supplements to provide antioxidant support, including some products intended to support reproductive health, and are also promoted for weight management and heart health. Evidence for these benefits in people is limited and mixed.
How It Works
Catechins neutralise harmful molecules called free radicals that can damage cells (oxidative stress). Oxidative stress is thought to affect egg and sperm quality, which is the reason catechins are included in some fertility support products. They may also have mild effects on fat metabolism and blood vessel function.
Dosage and Administration
Take as directed on the label, usually with food, as taking concentrated green tea extract on an empty stomach increases the risk of side effects. Do not take more than the recommended amount, and avoid combining several products that contain green tea extract.
Interactions
Green tea catechins can reduce the blood levels and effect of Nadolol and possibly other beta blockers, and may interfere with the cancer medicine Bortezomib. They can reduce the absorption of iron, so take iron supplements at a different time. Extracts that contain caffeine may add to the effects of other stimulants. Tell your doctor about all medicines and supplements you take.
Contraindications
- Liver disease.
- Allergy to green tea or other ingredients.
- Iron deficiency anaemia, unless a doctor agrees.
Side Effects
Possible effects include nausea, stomach upset and, if the product contains caffeine, sleeplessness, restlessness or a fast heartbeat. High doses of concentrated green tea extract, especially 800 mg or more of EGCG a day, have been linked with rare but serious liver injury.
Get urgent medical help if you notice yellowing of the skin or eyes, dark urine, pale stools, severe tiredness, pain in the upper right tummy, or signs of a severe allergic reaction such as swelling of the face or difficulty breathing.
Pregnancy and Lactation
Drinking moderate amounts of green tea is generally acceptable, but concentrated catechin supplements in high doses may reduce the body’s use of folic acid and contain caffeine. During pregnancy and breastfeeding, use only products designed for that stage or as advised by a doctor.
Precautions and Warnings
Stop taking it and see a doctor if signs of liver problems appear. People with anaemia, heart rhythm problems or anxiety should be cautious, especially with caffeine-containing extracts. Fertility problems need proper medical assessment.
Overdose
Very large amounts may cause vomiting, liver damage and, from caffeine, a racing heart and restlessness. Seek medical help and take the pack with you.
Therapeutic Class
Antioxidant plant extract (food supplement ingredient)
Storage
Store below 30°C in a dry place, away from light and out of the reach of children.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.