Theanine for Fibromyalgia & Chronic Fatigue Syndrome

Lots of Possible Benefits

Tea steeps in a glass mug.
Theanine comes from the tea plant. Jasmin Awad / EyeEm / Getty Images

Theanine Medicinal Uses:

Theanine is an antioxidant in tea leaves. It hasn't been studied specifically for fibromyalgia and chronic fatigue syndrome but is shown to be effective at treating many symptoms of the conditions.

Research shows theanine may:

  • Increase alertness
  • Boost energy
  • Relieve anxiety
  • Aid relaxation without drowsiness
  • Protect brain cells
  • Raise dopamine and norepinephrine
  • Lower glutamate activity
  • Balance glutathione
  • Boost T cell production
  • Prevent memory impairment due to improper blood flow (ischemia)

Theanine may also lower blood pressure and bad cholesterol, increase anti-tumor activity, and help regulate the sleep-wake cycle.

Theanine Dosage:

Studies have shown that theanine does cross the blood-brain barrier and that dietary levels of 50 mg per day can start to have a therapeutic effect. Depending on the quality and strength of the tea, that's about 3 cups per day.

Theanine is also available in supplement form, frequently as l-theanine or under the brand name suntheanine. A typical recommended dosage is 100 to 200 mg per day, but some studies have used up to 600 mg per day.

Theanine in Your Diet:

To get more theanine through your diet, you can drink black, green or white tea. The decaffeination process does not appear to lower theanine levels significantly, so decaf teas are an option as well.

(Theanine isn't in herbal teas, however.) The only other place theanine has been found in nature is in the Bay Boletus mushroom, which is native to parts of Europe and North America.

Side Effects of Theanine:

So far, researchers don't know of any significant negative side effects or drug interactions associated with theanine.

A short-term study on rats showed that repeated, extremely high doses cause few or no apparent harmful effects. (Watch your caffeine consumption, though!)

Theanine's safety during pregnancy and breastfeeding has not been established.

More Supplement & Neurotransmitter Information:


Amino acids. 2009 Jan;36(1):21-7. "Theanine, gamma-glutamylethylamide, a unique amino acid in tea leaves, modulates neurotransmitter concentrations in the brain striatum interstitium in conscious rats."

Asia Pacific journal of clinical nutrition. 2008;17 Suppl 1:167-8. "L-theanine, a natural constituent in tea, and its effect on mental state."

Current opinion in clinical nutrition and metabolic care. 2009 Jan;12(1):42-8. "Tea and health: preventive and therapeutic usefulness in the elderly?"

Journal of neuroscience research. 2008 Jun;86(8):1846-56. "Theanine, an ingredient of green tea, inhibits glutamine transport in neurons and astroglia in rat brain."

Journal of nutrition. 2008 Jan;138(1):1-4. "Bioactive food components that enhance gammadelta T cell function may play a role in cancer prevention."

Journal of pharmacological sciences. 2007 Oct;105(2):211-4. "Involvement of GABA(A) receptors in the neuroprotective effect of theanine on focal cerebral ischemia in mice."

Neurotoxicology. 2008 Jul;29(4):656-62. "Protective effect of the green tea component, L-theanine on environmental toxins-induced neuronal cell death."

Phytotherapy research: PTR. 2008 Jan;22(1):65-8. "Theanine prevents memory impairment induced by repeated cerebral ischemia in rats."

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