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I created this website so you would know
- why you need vitamin D3
- how best to take it.
It's a long story, but this is the short version:
Vitamin D3 will increase your quality-of-life and life-expectancy.
Best way to get D3? Sunlight, nature's own prescription.
But if we avoid the sun, we still have two choices:
- supplement an effective dose, or
- remain vitamin D-deficient.
Choose wisely!
Alex St Clair
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Recommended
Vitamin D3 capsules:
Vitamin D3 drops:
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This page contains...
Your vitamin D performance depends on body stores of vitamin D.
Raising your vitamin D level
Why such a large vitamin D reserve?
What happens if you take too much?
Taking the 25(OH)D vitamin D blood test.
Table of vitamin D blood levels.
Estimating your current vitamin D levels.
Free Download: D-Estimator
What to do next.
Vitamin D3 Capsules (5000 IU)
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Free Vitamin D Calculator
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D-Estimator
Vitamin D Calculator (Excel) Estimate your Vitamin D
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Healthy Vitamin D Levels
Why worry about vitamin D levels?
For a discussion on official vitamin D levels such as Adequate Intake Level and Safe Upper Limit, see Vitamin D RDA.
Most people think that if they take a big dose of vitamin D in the morning, they will have plenty of the active form of vitamin D available to them that day. That's how it works with vitamin B1 or vitamin C.
It doesn't work that way with vitamin D.
Vitamin D works differently
With vitamin D, the dose you take gets added to your vitamin D reserves - like a personal storage tank for vitamin D - held in your muscles, fat, tissues and blood.
The dose you take is quite tiny compared with the size of the tank, something like one drop of water in a barrel.
The tank is designed to hold enough vitamin D to last you all through the winter months when there is no sunshine.
So how much vitamin D gets activated? Well, that depends on the level in your tank. If it's low, vitamin D is conserved. If it's anywhere from about a third full to completely full, maximum activation of vitamin D can occur every day.
To put that differently, you only get maximum vitamin D health benefits if your tank is more than about a third full.
Doesn't sound like a problem. Why don't we fill your tank up to about half? That should be safe enough.
Why you need to know your Vitamin D Level
Not so fast. There are a couple of problems
- Since we are all different, we do not know how big your tank is
- If we get it wrong, and overfill your tank, you get sick from vitamin D toxicity
- One more thing we don't know is how full is your tank already?
As you can see, it's a bit tricky. If it was the car's gas tank we'd just look at the gauge and we would know how much gas to put in!
Well, we're in luck. There is a gauge, a way to measure how full is your vitamin D tank!
It's a vitamin D blood test, and you can use it to safely manage your vitamin D intake.
Vitamin D Blood Test
Specifically, you can use the blood test to
- find out if you are vitamin D deficient before you start supplementing
- monitor your vitamin D level after a few months of supplementation, to make sure you are nicely in the optimum range (or else you can adjust the dose).
The vitamin D blood test involves having a small amount of blood taken from a vein in your arm by a nurse or doctor, using a syringe.
It doesn't hurt, except for a momentary prick when the needle is inserted.
Which Vitamin D Blood Test?
The vitamin D blood test can be ordered through your doctor, or directly from a pathology lab. If you go to your doctor, you can discuss the results with her, and plan a dosage and testing strategy together. This is the route to follow if you are not in perfect health.
The correct vitamin D test is called a 25(OH)D blood test. It measures the amount of storage-form vitamin D (calcidiol) in your blood. (It shows you the level in your vitamin D tank.)
There is another kind of vitamin D blood test, usually called 1,25(OH)2D. This one measures the amount of activated vitamin D (calcitriol) in your blood.You don't want this test.
If your doctor orders the test for you, make sure she knows which one you want. Not all doctors are aware of the difference between the two tests.
Vitamin D Blood Test Results
Your pathology lab will report the result in either ng/ml or nmol/L like this:
Vitamin-D 25(OH)D 16.7 ng/ml (ref: 25 to 100 ng/ml)
The 16.7 ng/ml is the actual blood test result (this person was vitamin D deficient). The reference range indicates the range or spread of vitamin D values normally found in the whole population. Different labs show different ranges. The lab may go into more detail and give a table similar to the one below.
|
Table of 25(OH)D Blood levels |
||
|---|---|---|
|
Vitamin D Levels |
ng/ml | nmol/L |
| Severely Deficient | 0-10 | 0-25 |
| Deficient | 11-20 | 26-50 |
| Insufficient | 21-32 | 51-81 |
| Adequate | 33-49 | 82-124 |
| Optimum | 50-65 | 125-163 |
| High, but not toxic | 66-100 | 164-250 |
| Toxicity possible | above 100 | above 250 |
As you see, our optimum range is between 50 to 65 ng/ml (or 125 to 163 nmol/L). This is the level which is sustained naturally by healthy individuals who spend a proportion of each day in the sun, without much clothing. Just as our ancestors have been doing for the last two million years, or so.
This is the vitamin D level we want to reach, and maintain all year round.
Once you take the blood test you will know if you are vitamin D deficient, or not, and can plan your dosage strategy accordingly.
Estimating your vitamin D levels
If you haven't taken a vitamin D blood test, you can estimate your vitamin D levels.
It's easiest to estimate your levels at the end of summer and then work forwards from there. You'll see what I mean in a moment.
By the end of summer:
- People who spend a great deal of time in the sun, for example lifeguards, may reach the High-but-not-toxic range.
- People who work or play outdoors in the sun almost everyday, with at least arms and lower legs exposed to strong sunlight, without sunscreen, may reach the Optimum range.
- People who make no conscious effort to avoid the sun (by covering up or applying sunscreen) and who expose at least arms and lower legs to direct sunlight for several minutes most days, but who do not have daily outdoor work or hobby activities, may reach the Adequate range.
- People who tend to avoid the sun, stay indoors at lunchtime, put on sunscreen when they go out at weekends, but eat a good diet and take a daily multivitamin supplement containing 400 IU of vitamin D, may reach the Insufficient range.
- People who carefully avoid the sun at all times and do not take even 400 IU per day of vitamin D in a multivitamin or other supplement, may reach the Deficient range.
These end-of-summer vitamin D levels are for people who are young and trim. Overweight people, and those over 50 years of age may maintain a level one below that of slim, younger people.
No matter what your condition, from the end of summer onwards you can expect your vitamin D levels will decline by one band of the table, every two months or so. The decline will continue (unless you supplement with an effective dose of vitamin D) until you are able to obtain sunlight again.
This rough estimate of your vitamin D level has not taken into account your skin-type, the latitude where you live, or variations in individual vitamin D absorption and metabolism.
But it is a good starting point for estimating your vitamin D status. It may also help you to understand why most people are vitamin D deficient for at least part of the year.
There is another, more accurate way to estimate your vitamin D levels.
Free Vitamin D Calculator
It is our vitamin D calculator called D-Estimator.
It takes into account your age, body mass, sun exposure, clothing coverage, skin type and geographic latitude, as well as how much vitamin D you take in from food and supplements.
D-Estimator is a useful educational tool, and you can use it to predict your own vitamin D blood level.
But because individuals' vitamin D metabolism varies, your actual blood level may be different from the predicted value. So it does not replace a blood test!
Another use for D-Estimator is to calculate a vitamin D dosage tailored to your measurements.
D-Estimator is a small (45kb) Excel file which downloads quickly. It's also free, with my compliments. Download D-Estimator.
After downloading, save it to your hard drive so you can use it whenever you wish. To use it, just click on the file. It will open in Excel. You will need to know your geographic latitude (see infoplease) and body mass.
If you use D-Estimator and also take a 25(OH)D blood test, feel free to contact me (Alex St Clair) and let me know how D-Estimator's prediction compared with your blood test.
Vitamin D Action Plan
So if you know your vitamin D blood level, and you're ready to take action, what should you do?
|
25(OH)D Blood levels - and what to do about them |
|||
|---|---|---|---|
|
Vitamin D Levels |
ng/ml | nmol/L |
Action |
| Severely Deficient | 0-10 | 0-25 |
Take Deficiency-Correction Dose |
| Deficient | 11-20 | 26-50 |
Take Deficiency-Correction Dose |
| Insufficient | 21-32 | 51-81 |
Take Deficiency-Correction Dose |
| Adequate | 33-49 | 82-124 |
Take Maintenance Dose |
| Optimum | 50-65 | 125-163 |
Take Maintenance Dose |
| High, but not toxic | 66-100 | 164-250 |
Take no vitamin D |
| Toxicity possible | >100 | >250 |
Take no vitamin D - See Doctor |
If you need to take a Deficiency-Correction dose, see Vitamin D Deficiency
If you need to take a Maintenance dose, see Vitamin D Dosage
