By Ralph Golan, MD

There has been a plethora of new vitamin D research in the last few years, and it is becoming evident that it is one of the most important vitamins. Low vitamin D levels put one more at risk for colds, the flu, osteoporosis, cancer of the breast, prostate, colon and several more types of cancer, autoimmune diseases such as multiple sclerosis and rheumatoid arthritis, and other serious conditions. It has been reported recently that infant rickets is on the rise (a frank vitamin D deficiency incurred in utero. And cases of autism are now being linked, in part, to the inability of the body to excrete toxic metals and chemicals as an indirect result of vitamin D insufficiency.

The vitamin D Council puts out a newsletter with the most recent research and clinical findings regarding this all important nutrient. And I am sure you have seen a lot in the news and in health newsletters that you may receive on this subject, so I am going to keep my discussion here brief and emphasize only a few points.

Many sources suggest that sunlight exposure is the very best source for this vitamin, and there are very safe ways to achieve adequate vitamin D levels from the sun and from tanning booths. (You can never overdose with vitamin D this method, but you certainly can overdose your skin and eyes with UV radiation!) However, with our shortening days and not that much sun this summer anyway (at least in the Seattle area), and for all those who live in northern latitudes or spend the majority of the day indoors, our opportunity to make our own vitamin D from sunlight exposure is restricted. Furthermore, the older we get, our sun-induced vitamin D synthesis capability diminishes.

So vitamin D is a critical supplement to take. Most adults and even children over one year old can safely take 1000 to 2000 IU (international units) a day of vitamin D 3 or cholecalciferol according to the recommendations of the US Institute of Medicine of the National Academy of Sciences. (Those with chronic kidney disease and other metabolic disorders need some physician dosing supervision.) Although I agree that most of us need a lot more vitamin D than the 400 IU stated as the minimal daily requirement on most multivitamin bottle labels, I am uncomfortable making a general recommendation of 2000 IU a day for a 2 year old or even a 10 year old. Too much vitamin D can have serious consequences.

An excess of vitamin D in our bodies can cause vomiting, constipation, weight loss, kidney failure, and calcifications in the arteries. These problems may not become evident until long after your body has reached toxic levels, and it takes months of discontinuing vitamin D before the levels come back down to normal. Furthermore, it has been suggested that the vitamin D receptors in our cells that control over 1000 genes can dysfunction with too little or too much vitamin D. So, like with many supplements that are good for us, too much vitamin D can become problematic.

I am not providing this information to discourage you from supplementing with vitamin D. In fact, the majority of us is deficient, and we need to supplement to protect and optimize our health. I have read reports that suggest during the fall-winter months, most adults can safely take 5000 IU daily of vitamin D 3. Just realize that more is not always better.

But how can we determine just what is the best dose?

According to the Vitamin D Council which reports all of the latest vitamin D research, all of us taking vitamin D should have our blood levels of vitamin D measured (actually 25 hydroxy vitamin D, also known as 25 OH vitamin D). In this way we can assure that we are in an optimal range – which is not only a safe, non-toxic level but one that affords us all of vitamin D's protection. Although the normal range is quite broad (20-56 ng/ml) the optimal range is 45-50 ng/ml. Reported in different units, 115-128 nmol/l is optimal whereas 50-140 nmol/l is normal. If we want to be optimal, testing is essential.

And to deepen the issue a bit more, the test needs to be run at a lab that performs the DiaSorin RIA or Diasorin Liaison method. If the lab uses the old LC-MS/MS method (the most popular one) and has not calibrated the test to the Diasorin results, then results usually will look 25-40% higher than they really are. This discrepancy has serious implications about dosing. It may suggest your levels are normal when in fact they are low, and your doctor may then mistakenly tell you your current dose is adequate, when in fact it is not high enough. Or he or she may tell you your levels are high and that you need to lower your dose, when in fact your level may be optimal and your current dose is perfect. So if you want to assure optimal vitamin D levels, you need a blood test for 25 OH vitamin D, and from a lab that provides the right test. (In our office, we use labs that offer the Diasorin method.

I know that a lot of you will reject the idea of doing a blood test for vitamin D level. After all you have probably not done tests to assure optimal levels of other vitamins you have taken. I consider vitamin D an exception because it is really more a hormone, and also it has been shown to be so vital for health protection.

If you still insist on "winging it" and just supplementing with vitamin D and not testing, using 2000 daily of D 3 is likely fine for an adult and high schooler, and in the fall-winter months if you do not live in southern latitudes, then use up to 4000 to 5000 IU daily.

Cod liver oil is a fine way to get in vitamin D. It is the natural form (whereas the vitamin D-3 in capsules is synthetic). Cod liver oil also contains vitamin A –also an immune fortifier, as well as the omega 3 oils EPA and DHA so useful for brain and eye and heart health. Omega 3's also function as a natural anti inflammatory. I like Carlson's Norwegian Cod Liver Oil right out of the bottle (it is flavored so it is not fishy tasting), or their capsules of Super 1000 Cod Liver Oil. Carlson's tests and verifies that their cod liver oil is free of ocean pollutants ( mercury, lead, DDT, etc) and is fresh (very low levels of lipid oxidation).

Most adults and high school age kids can safely take 1 tablespoon a day of the oil which provides 1200 IU of vitamin D and up to 3600 IU of vitamin A. 2 tablespoons daily may be a better dose. Or take up to 5 capsules of the Super 1000 capsules which provides 1250 IU of vitamin D and 10,000 IU vitamin A. Much younger kids should probably not get much more than 5000 IU daily of vitamin A, and unless blood tested, not more than 800 IU a day of vitamin D (I may change my opinion on this in the near future). So for younger kids, they can take still up to 1 tablespoon of the oil, less if under 75 pounds, and as the Super 1000 caps are rather large, Carlson's offers a smaller gel cap that has less amounts of everything. Be sure you do not dose it over 5000 IU daily for the vitamin A for kids under 75 pounds.

You can find plain vitamin D capsules in health food stores. Be sure you use vitamin D 3 (cholecalciferol) and not vitamin D 2 (ergocalciferol), as the latter converts in the body to the active form 500 times slower than D 3. It comes usually in 400, 800, 1000, and 2000 IU sizes. Vitamin D also comes in drops.

I personally need 5000 IU of vitamin D 3 daily to keep my levels up in the high 40's, so I take some Cod Liver Oil and some extra vitamin D drops.

If you are not over 50 years old generally, and you spend a fair amount of time in the sun, you may require a smaller dose in the summer months, possibly a much smaller dose. The same applies as well if you live in southern latitudes where the sun is shining year around.

Again, I recommend vitamin D testing to determine if you need to supplement at all (very likely) or if you need to supplement any more than you currently do. Retesting (using the right lab) will help you find your best dose. This simple test and supplement can protect your future health in very major ways.

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