Taking multivitamins is a quick and efficient way to replenish your nutrient reserves. However, contrary to popular belief, our bodies don’t completely absorb all vitamins from a multivitamin supplement.
So, let’s check out the absorption rates.
What Percentage of a Multivitamin Is Absorbed?
Our bodies absorb only roughly 10% of vitamins from multivitamin capsules or tablets. This is because our stomachs usually break down vitamins before they get a chance to get absorbed due to the nature of multivitamin tablet/capsule casing.
Eye-Opening Stats and Facts on How the Body Absorbs Multivitamins
Now that we established that the body only absorbs a fraction of vitamins from multivitamin supplements let’s find out what influences the absorption rate and how it varies in different vitamins.
The absorption rate of vitamin B12 varies inversely with quantity.
Vitamin B12 has an absorption rate of 50% at a 1–2 mcg dose. The absorption gets drastically lower at higher doses. For example, only 2% of cobalamin gets absorbed at doses of 500 mcg, and the rate gets even lower (1.3%) at 1,000 mcg.
The absorption rate of vitamin C varies from 50% to 90% based on quantity.
The absorption rate of vitamin C is roughly 70–90% when taken in daily doses of 30–180 mg. However, when taking doses of over 1 g/day, the absorption rate falls below 50%, and the remaining unmetabolized fraction gets eliminated through urine.
Vitamin E’s typical absorption rate is 10–95%.
Vitamin E absorption rate depends on many factors, including food matrix, age, gender, the individual’s general health, etc.
The body absorbs about 80% of vitamin K from supplements.
While the absorption rate of vitamin K in its free form (from supplements or oils) is impressive, it’s not as noteworthy when this vitamin is obtained from food sources (e.g., spinach). This is likely because phylloquinone in plants is more tightly bound to chloroplasts.
Certain medical conditions and procedures can reduce the absorption rate of vitamin D.
- Celiac disease
- Chronic pancreatitis
- Cystic fibrosis
- Crohn’s disease
- Liver or kidney disease
- BMI over 30
- Radiation treatment
- Weight loss surgery
Certain medications can reduce the absorption rate of vitamin D.
They include oral steroids, statins, orlistat, and diuretics.
The intake of certain substances can reduce vitamin A absorption.
For example, cholestyramine and neomycin are two popular drugs that may reduce vitamin A absorption. Additionally, prolonged use of mineral oil and high infection rates (especially diarrhea) may also interfere with the absorption of this nutrient.
Vitamins’ absorption rate depends on various factors. They include the consumers’ general health, their medication intake, the type of vitamin, dosage, etc.