ProCaps Laboratories Vitamin D3-4000

Our assessment

The evidence shows that this product contains 4,000 IU of vitamin D3 per serving. For most adults, the recommended daily allowance is 600 IU, with a safe upper limit of 4,000 IU [NIH ODS]. You should be aware that taking 4,000 IU daily is the maximum safe intake for adults, and you should not take additional vitamin D supplements without consulting your healthcare provider [NIH ODS]. Data not available for specific clinical studies on this exact product.

How it works

Think of vitamin D as a master regulator for calcium absorption. It works alongside calcium to support bone mineralization and neuromuscular function [NIH ODS]. The 4,000 IU dose is designed to help maintain adequate vitamin D levels, especially if you have limited sun exposure or absorption issues [NIH ODS].

Safety profile

FDA received 592,059 total adverse event reports across all supplement categories. For vitamin D, side effects from excessive intake include 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 [FDA data] [NIH ODS]. Calcium in this product can reduce absorption of bisphosphonates, tetracycline antibiotics, fluoroquinolone antibiotics, levothyroxine, and phenytoin [NIH ODS]. Some research suggests high calcium intakes might increase risk of heart disease and prostate cancer [NIH ODS].

Our recommendation

Start with a blood test to check your current vitamin D level before taking 4,000 IU daily. If your levels are adequate, a 600-800 IU maintenance dose is safer for long-term use [NIH ODS]. Take this supplement with food for better absorption, and separate it from thyroid medication or antibiotics by at least 4 hours [NIH ODS]. Do not exceed one serving per day, as 4,000 IU is the upper tolerable limit for adults [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