Mayo Clinic recommends that adults get at least the RDA of 600 IU. However, 1,000 to 2,000 IU per day of vitamin D from a supplement is generally safe, should help people achieve an adequate blood level of vitamin D, and may have additional health benefits.
Recent RCTs like the Vitamin D and OmegA-3 Trial (VITAL) gathered safety data on using 2000 IU of vitamin D/day in general adult populations who showed no signs of vitamin D toxicity for 5.3 years, indicating the safety of this daily dosage.
The main concern of vitamin D toxicity is a buildup of calcium in the blood. This is called hypercalcemia. Hypercalcemia can cause upset stomach and vomiting, weakness, and frequent urination. It also can lead to bone pain and kidney troubles such as kidney stones.
Unless your doctor recommends it, avoid taking more than 4,000 IU per day, which is considered the safe upper limit. Choose food over pills.
The dose of vitamin D you need to take to produce toxic signs and symptoms varies greatly. It can occur with as little as 2,000 international units per day (IU/d) in susceptible people. Healthy daily requirements for vitamin D include: People ages 19 to 50: 600 IU/d.
Neither normal nor excessively high intakes of vitamin D are associated with liver injury or liver test abnormalities.
The effect of equivalent oral doses of vitamin D3 600 IU/day, 4200 IU/week and 18,000 IU/month on vitamin D status was compared in a randomized clinical trial in nursing home residents. A daily dose was more effective than a weekly dose, and a monthly dose was the least effective.
Answer From Katherine Zeratsky, R.D., L.D. Vitamin C is an essential nutrient, but you can get too much of it. If you're an adult, limit yourself to no more than 2,000 milligrams (mg) of vitamin C a day. The recommended upper limit for children varies by age.
Too much vitamin D can be toxic. The recommended maximum intake is 25 mcg (1,000 IU) for infants and 50 mcg (2,000 IU) for children and adults with normal kidney function.
As described previously, the products of vitamin D metabolism are excreted through the bile into the feces, and very little is eliminated through the urine. This is in part due to renal reuptake of vitamin D metabolites bound to DBP, as mediated by the cubilin–megalin receptor system (Willnow and Nykjaer, 2005).
Safety and side effects
However, taking too much vitamin D in the form of supplements can be harmful. Children age 9 years and older, adults, and pregnant and breastfeeding women who take more than 4,000 IU a day of vitamin D might experience: Nausea and vomiting. Poor appetite and weight loss.
If you've been getting bone, muscle or joint pain, your symptoms are likely to get better when your vitamin D levels are normal again. This is usually after a few weeks or months.
There are quite a few differences between vitamin D and vitamin D3, but the main difference between them is that vitamin D is a fat-soluble vitamin that regulates calcium and phosphorous levels in the body, whereas the vitamin D3 is the natural form of vitamin D produced by the body from sunlight.
The best food sources of vitamin D are oily fish, including salmon, mackerel, and sardines. Other sources include egg yolks, red meat, and liver. Vitamin D is added to some foods too, including breakfast cereals, plant milks and fat spreads. Check information on-pack to see if this applies to the products you buy.
Mayo Clinic recommends that adults get at least the RDA of 600 IU. However, 1,000 to 2,000 IU per day of vitamin D from a supplement is generally safe, should help people achieve an adequate blood level of vitamin D, and may have additional health benefits.
Some water-soluble vitamins, if taken in very large doses, consistently can cause problems. The following can happen if you take three to 10 times above the recommended limit: Vitamin C - nausea, diarrhea, vomiting or headaches. Vitamin B3 - stomach pain, high blood pressure, vision problems and liver damage.
Fat-soluble vitamins (like A, D, E, and K) don't get flushed out in the urine, so they're the most likely to cause vitamin toxicity. Vitamins A and E may pose the greatest risk of toxicity, since they are so commonly taken and readily available.
Do not take more than 100 micrograms (4,000 IU) of vitamin D a day as it could be harmful. This applies to adults, including pregnant and breastfeeding women and the elderly, and children aged 11 to 17 years. Children aged 1 to 10 years should not have more than 50 micrograms (2,000 IU) a day.
Vitamin D toxicity is a known cause of hypercalcemia and renal failure.