Short answer

We found no documented interaction between Calcium and L-theanine in the sources below. That isn't proof the combination is right for you: check each one's cautions, and ask your pharmacist if you take medication.

Calcium

What it is: The body's most abundant mineral; it builds bones and teeth and helps muscles, nerves and blood vessels work.

What the research says: Calcium supports bone health, especially when diet falls short. Vitamin D helps the body absorb it.

Cautions

• Upper limit from all sources: 2,500 mg a day for adults 19 to 50, and 2,000 mg from age 51.
• Some research links very high intakes to heart disease and prostate cancer risk.

Medicines to check

• Levothyroxine (thyroid medicine): keep doses apart
• Quinolone antibiotics: keep at least 2 hours apart
• Dolutegravir (HIV medicine) and lithium

In Holitro: Calcium Citrate (160 mg per capsule)

Source: NIH Office of Dietary Supplements: Calcium: Fact Sheet for Consumers (updated September 2023)

L-theanine

What it is: An amino acid found in green tea, taken for calm and sleep.

What the research says: Small studies suggest it may improve sleep; results for anxiety are mixed.

Cautions

• No side effects have been reported for the supplement.
• It may not be safe in pregnancy or while breastfeeding.

Medicines to check

• Sleep medicines and sedatives (such as lorazepam, diazepam or zolpidem): may add to drowsiness

In Holitro: Theanine 200mg (200 mg per capsule)

Source: Memorial Sloan Kettering Cancer Center, About Herbs: L-Theanine (updated July 2026)

Check with your doctor or pharmacist, especially if you take medication.

Check your stack — free

Educational information only, not medical advice. This reflects general ingredient overlap, not a personalized safety review. Always check with your doctor or pharmacist before combining supplements, especially if you take medication, are pregnant or nursing, or manage a health condition. These statements have not been evaluated by the FDA.