side effects of high dosages | blood test | 5,000 vs 10,000 IU daily | daily or weekly | guidelines
A daily vitamin D dosage of 4,000 IU is pretty safe in most cases. Moreover, even daily dosages of 10,000 IU can help people deal with vitamin D deficiency and it’s unlikely to cause vitamin D toxicity.
What vitamin D does in the body?
Vitamin D is vital for strong bones and may protect from osteoporosis. Also, vitamin D is necessary for many other functions of the human body. Vitamin D deficiency has been linked to increased risk of hair loss, dry skin & wrinkles, cancer, cardiovascular disease, depression, multiple sclerosis, diabetes, obesity, decreased testosterone levels, and constipation.[1]
Side effects of too much vitamin D from supplements
High dosages of vitamin D from supplements can be toxic. If you’re taking vitamin D supplements, you should consult your health care provider. You better have a blood test regularly, in order, to check your serum concentration of vitamin D.
Side effects of excess vitamin D may be increased calcium levels in the blood. Hence, side effects, such as nausea, vomiting, muscle weakness or pain, loss of appetite, dehydration, thirst, and kidney stones may occur.
Vitamin D toxicity may happen from extreme dosages from supplements. Vitamin D toxicity is rather difficult to be caused by food or sun exposure:
- sun exposure can’t result in vitamin D toxicity, as the hot skin limits the formation of D3. On the contrary, tanning may cause vitamin D toxicity. There are cases that often application of artificial UV radiation increased blood levels of vitamin D above 375–500 nmol/L (150–200 ng/mL)!
- cod liver oil is the richest dietary source of vitamin D. It contains 1,360 IU per serving! Other good dietary sources of vitamin D are fish, such as trout and salmon, as well as all fortified products.
What’s the normal range for vitamin D in a blood test?
As a rule of thumb, vitamin D levels in the blood should be between 50-75 nmol/L or 20-30 ng/mL. Analytically:
| nmol/L | ng/mL | Health status |
| less than 30 | less than 12 | severe deficiency |
| between 30-50 | between 12-20 | inadequate |
| between 50-125 | between 20-50 | adequate |
| higher than 125 | higher than 50 | potential side effects |
| higher than 150 | higher than 60 | may cause toxicity |
In any case, consult your doctor before starting vitamin D supplementation. Especially, if you’re on medication.
How much vitamin D do we need daily?
The recommended daily intake of vitamin D for most adults is 600 IU. Elderly people should take a higher dosage of 800 IU per day. Furthermore, the safest upper daily dosage of vitamin D is 4,000 IU per day.
Is a daily 5,000 IU dosage of vitamin D safe?
But, what’s the upper vitamin D dose per day for adults? Most vitamin D supplements contain 5,000 IU of vitamin D per pill. Is 5,000 IU a safe dosage for daily consumption?
The FNB recommends no more than 4,000 IU for adults a day.[1] That’s a pretty conservative dosage, though. Even daily dosages of 10,000 IU are considered safe with low risk of toxicity.[2]
If you’re taking vitamin D supplements for a long time, you should check your blood concentration. Above all, consult your physician. You shouldn’t exceed toxicity levels.
Vitamin D supplementation guidelines
Is it better to take vitamin D every day or once a week?
Taking vitamin D supplements every day is the most effective way to increase your serum vitamin D levels. Supplementation once a week or once a month was less effective.[3]
Furthermore, weekly vitamin D dosages of up to 100,000 IU are considered pretty safe, for treating vitamin D deficiency. In a study, vitamin D supplementation for a year with this dosage didn’t cause vitamin D toxicity.[4]
Certainly, you better limit your daily vitamin D dosage to 10,000 IU. Above all, check your vitamin D levels in your blood regularly and consult your physician for your own daily optimum vitamin D dosage.
How many times a week should I take vitamin D?
If you have severe vitamin D deficiency, you may need higher daily dosages of vitamin D. After a few months, you’ll probably need to decrease the daily dosage, in order, to prevent vitamin toxicity.
So, if you have serum vitamin D levels less than 20 ng/mL, you should start consuming 10,000 IU of vitamin D every day for 2 months. Then, check your vitamin D levels in your blood. If your vitamin D levels in the blood are above 30 ng/mL, you can limit your daily vitamin D dosage to 4,000 IU. 4,000 IU dosage is the daily upper limit for vitamin D.
Certainly, you may need to skip vitamin D supplementation. Especially, if you have serum vitamin D levels above 50 ng/mL. It’s important to have your blood levels checked regularly.
Is it OK to take vitamin D every day?
If you have low serum vitamin D levels, you can take a daily dosage of 4,000 IU of vitamin D which is pretty safe for most people. Moreover, even 10,000 IU daily are considered safe for most people. Certainly, you shouldn’t take 10,000 IU for a long time, without consulting your doctor and have your blood levels checked.
What’s the best time to take vitamin D?
You should take vitamin D supplements with a meal. As vitamin D is a fat-soluble vitamin, it’s best absorbed when we eat food that contains fat. Seeds and nuts are the healthiest sources of fat. Moreover, seeds and nuts are among the most nutrient-dense food you can have. For instance, walnuts and flaxseeds are the best dietary sources of the omega-3 fatty acids.
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