There are a number of variables that determine what vitamin D dosage would be best for you. It's really not possible to recommend the same amount for everyone. Fortunately, there are many clues to look for that will give you a pretty good idea whether or not you should supplement, and how much you should take.
How much sun exposure do you get every day? Twenty or thirty minutes in the middle of the day, a few times a week, are all that you need in the summer.
What time of the year is it? Unless you live in the tropics, the sun's rays are too weak to manufacture vitamin D for about 6 months out of the year. By spring, your levels are at their lowest for the year.
How far from the equator do you live? The further away you are, the less vitamin D you're able to manufacture from sun exposure.
What is your age? Your capacity to manufacture vitamin D diminishes with age.
Is your skin light, dark or very dark? Darker-pigmented skin acts like a sunscreen and inhibits the manufacturing of vitamin D.
Are you overweight? People with lots of body fat don't manufacture vitamin D as well as most people.
Do you have any chronic illnesses? If your immune system is overloaded, your vitamin D levels can become depleted.
Find out more about factors that influence your vitamin D dosage at
Causes of Vitamin D Deficiency
Dr. John Cannell of the Vitamin D Council suggests that you take 1,000 IU per 25 pounds of body weight as a starting vitamin D dosage. A person who weighs 150 pounds, for instance, would take 6,000 IU per day.
Do this for at least eight weeks, and then get a vitamin D test. Perhaps this dose will put you in the ideal range, but there's no guarantee, since we are all different. The idea is to hopefully get somewhere in the ballpark and then tweak your daily dose from there.
If your blood levels are still low, Dr. Cannell estimates that each 1,000 IU increase in your vitamin D dosage will produce about a 10 ng/ml increase in the vitamin D blood level. For example, if you have been taking 5,000 IU per day for 8+ weeks, and your results come back at 40 ng/ml, you would want to increase your dose to at least 7,000 IU to achieve a minimum of 60 ng/ml.
Again, keep in mind that this is just a generalization; additional blood testing periodically will verify it, if necessary.
Generally Recommended Dosages for Preventive Health. If you just want to use supplements for general health benefits, the typical vitamin D dosage calls for at least 1,000-2,000 IU daily. 5,000 IU per day is not unreasonable in the winter months. It's also a good dose if you get little or no sunlight, live in northern latitudes, or are dark-skinned or overweight.
The only way to know your exact vitamin D dosage is by testing your blood. Fortunately, testing vitamin D is not expensive, as blood tests go. You can set one up with your doctor, order a test online and get blood drawn at a local lab, or order a vitamin D home test kit.
Make sure you get the correct test. There are two vitamin D tests currently being offered: 1,25(OH)D, and 25(OH)D. The correct test to order is 25(OH)D, also called 25-hydroxyvitamin D, which is the better indicator of overall D status. Surprising as it may seem, many doctors are unfamiliar with the different vitamin D tests.
See my page on Vitamin D Blood Test
for more information.
Vitamin D toxicity seems to be a very common notion today, especially among physicians. If you examine it closer, though, it's a theory based on very flimsy evidence and often misinterpreted observations taken from a handful of unusual cases.
Cholecalciferol/vitamin D is certainly toxic in excess. However, vitamin D toxicity is virtually unheard of until the dose exceeds 10,000 IU per day. In adults, taking 50,000 IU/day for more than a few months can produce toxicity. However, there would be no reason for anyone to do this, unless they are being treated for vitamin D deficiency by a health care provider.
See my page on Vitamin D Toxicity for more details.
In order to achieve consistent and predictable results, the best form is an oil-based vitamin D product. Vitamin D is fat soluble, and needs to be taken with fat in order to be properly absorbed.
There are two common types of vitamin D: Vitamin D3 (cholecalciferol) and Vitamin D2 (ergocalciferol). You want to avoid supplementing with vitamin D2, which is a synthetic product. D3 is what your body naturally uses and prefers.
I recommend getting vitamin D drops because they're so easy to keep on hand.
Other great resources for vitamin D information:
Grassroots Health A consortium committed to solving the worldwide vitamin D deficiency epidemic.
Dr. Mercola's Video Lecture on the latest science on vitamin D.
How Much Vitamin D Do You Need? Also by Dr. Mercola.
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