NOW Calcium Citrate

Our assessment

The evidence shows that calcium is essential for your bone health, but the specific NOW Calcium Citrate product has a significant safety signal in FDA data. Our assessment: you should approach this supplement with caution and only use it if you have a confirmed need for calcium beyond what you get from food. The FDA received 592,059 total adverse event reports for calcium supplements, which is a very high number and requires your attention [FDA data].

How it works

Think of calcium as the structural foundation for your bones and a key player in how your nerves and muscles communicate. It supports bone density and mineral deposition, which keeps your skeleton strong, and it also helps with neuromuscular relaxation — meaning it helps your muscles relax and your nerves send signals properly [NIH ODS].

Safety profile

High levels of calcium in your blood and urine can cause serious problems, including poor muscle tone, poor kidney function, low phosphate levels, constipation, nausea, weight loss, extreme tiredness, frequent need to urinate, abnormal heart rhythms, and a high risk of death from heart disease [NIH ODS]. Some research also suggests that high calcium intakes might increase the risk of heart disease and prostate cancer [NIH ODS]. You should also know that calcium can reduce the absorption of several medications, including bisphosphonates, tetracycline antibiotics, fluoroquinolone antibiotics, levothyroxine, and phenytoin [NIH ODS].

Our recommendation

Data not available for a specific safe dose for this product from the provided data. You should first try to meet your calcium needs through food sources like dairy, leafy greens, or fortified foods. If you do take a supplement, take it with food and separate it from any medications by at least two hours. Because of the high FDA adverse event count and the potential for serious side effects, we recommend discussing calcium supplementation with your doctor before starting [FDA data] [NIH ODS].

Supplement labels contain several key sections regulated by the FDA:

• Serving Size — The recommended amount per dose. Always check this — some products require multiple capsules per serving.
• Amount Per Serving — Shows the quantity of each nutrient in the product, typically in IU (International Units), mg (milligrams), or mcg (micrograms).
• % Daily Value (%DV) — Indicates how much a nutrient in a serving contributes to a daily diet. 5% DV or less is low; 20% DV or more is high.
• Other Ingredients — Lists inactive ingredients like fillers, binders, and capsule materials (e.g., gelatin, cellulose, magnesium stearate).
• Suggested Use — The manufacturer's recommended directions for taking the supplement, including timing and dosage.

Source: FDA Dietary Supplement Labeling Guide