How do we obtain vitamin D?
How much VITAMIN D do we need?
Vitamin D requirements are highly Individual – vitamin D status is dependent on numerous factors, such as your skin color, your location, and how much sunshine you’re exposed to on a regular basis. The ONLY way to be sure, is to get your blood level tested.
Measuring body’s vitamin D blood levels
Your body stores vitamin D for a few weeks or months – if you get enough sun exposure during the summer months, you may have enough to carry you through the winter, but without enough exposure to winter sun, taking a vitamin D supplement may be your best option during that cloudy season.
Conventional (woefully deficient) RDAs:
• 400 IU for infants, children and adolescents | • 200 IU for adults up to age 50 |
• 400 IU for adults aged 51 to 70 | • 600 IU for seniors over 70 |
Since the RDA for vitamin D was set in 1997 at 400-600 IU (International units), there have been more than 3000 studies finding that this level is barely sufficient to even prevent rickets (weakened bones) and does nothing to protect from cancer, heart disease and infections. To get a feel for vitamin D amounts, realize that under ideal conditions it is frequently possible to generate ~ 20,000 IU of vitamin D by exposing your skin to the sun.
Recommended daily vitamin D Intake for OPTIMAL health is 35 IU’s of vitamin D per pound of body weight. Based on the most recent research E.g. For a 40# child, the recommended average dose would be 1,400 IU /day, and for a 170# adult, the dose would be nearly 6,000 IU’s.
- An estimate is that the body uses a daily average of 3-5,000 IU of vitamin D. Barger-Lux MJ etal, 1998. PubMed
- Daily vitamin D intake of 10,000 is safe. Concluded R. Vieth concluded from his 1999 studies having observed no adverse effects in adults (assuming no hypersensitivity).
- Consume ~4000 IU daily vitamin D3 if we are not obtaining vitamin D3 from sun-exposure. Suggested Dr. John Cannell of the vitamin D Council and Robert Heany of Creighton University (author of the article “The vitaminD Requirement in Health and Disease”) to maintain a CALCIDIOL blood level of ~ 50 ng/ml. .
Blood CALCIDIOL levels
- As high as 46 ng/m appear to maximize the body’s ability to regulate blood sugar. Heaney Robert P, 2005
- Maintained at no less than ~30 ng/mL for maximum calcium absorption – Blood levels of CALCIDIOL, In the absence of UV-B light, this would require ~2600 IU per day of dietary vitamin D. (However, fracture risk continues to fall with higher levels of CALCIDIOL because people actually fall less often, suggesting a neuromuscular benefit to higher vitamin D levels).
Sources of vitamin D
Prefer to obtain vitamin D from sun and food
Sunshine-derived vitamin D
We are designed to be in the sun – ideally, we can produce vitamin D3 from UV-B spectrum sunlight acting on the skin which converts cholesterol precursor(7-DHC) in the skin into D3. UV-B rays occur when the zenith angle of the sun is > 45°, typically 10am to 2pm, and depends on latitude and season. Obtaining sun at these times optimizes skin’s vitamin D production, whilst minimizing UV-A damage to skin.
A light skinned person needs at least 30 minutes of ~ 1/3 body (arms, lower legs, face, hands) exposure, without sunscreen, and with clear skies (Up to 1 or more hours may be needed for darker skinned people and the elderly).
For more information on how to effectively and safely obtain vitaminD3 by exposing skin to sunlight:
Food sources of vitamin D
Food Sources of vitamin D3
Natural D is best – Since vitamin D levels are so critically balanced with other nutrients, prefer to obtain D3 from sun or food sources, rather than taking unnatural quantities of isolated D3 (or synthetically derived D2) as a supplement.
Vitamin D is not transferred in breast milk. The best source of Vitamin D for babies is by exposing skin to the sun – the same as for older children and adults.
- Cod or other fish liver oil. High vitamin D Cod liver oil -1150 IU / tsp.
- Oily fish – stored in their fat, is vitamin D made from the vitamin D precursor found in algae. Farm-raised salmon are probably poor sources of D, since they are unlikely to have eaten very much algae; Oily fish (E.g. mackerel, salmon, herring) -~400 IU / 3.5 oz
- Butter from grass-fed cows / Fat of vertebrate mammals. Vitamin D is made from precursors in lichen and green grass. Vitamin D is in the butterfat of ruminant animals that feed on green grass. Like humans, pigs that spend time in the sunlight convert sunlight to vitamin D in their skin and store it in their fat.
- Eggs – From chickens whose diet contains vitamin D (e.g. insects or fishmeal). 1 large fried egg – 17 IU
Food Source of vitamin D2
Sun-exposed / dried mushrooms can provide a significant source of D2. Sun-exposed, sliced and dried mushrooms retain their high vitamin D2 content for many months and provide a good, NATURAL, supplemental source those who do not see the sun too much during those winter months.
Vitamin D from Supplements / Fortified Foods
Fortified whole-fat milk. 1 cup whole milk (vitamin D added, look for the D3 form, not D2) -98 IU
D2 vs. D3. The two manufactured forms typically used to fortify food, such as milk, orange juice, bread and cereals, and used in vitamin supplements are:
- Vitamin D3 (cholecalciferol). Typically made by irradiating lanolin from sheep’s wool with ultra-violet light.
- Vitamin D2(ergocalciferol) Synthesized in a lab setting, usually by irradiating ergosterol (plant D2 precursor) extracted from yeast.
Studies conclude that vitamin D3 is considerably more potent than D2 (conservatively stated at 4 times more potent). In one particular study, although both D2 and D3 initially produced a similar rise in blood CALCIDIOL, after 3 days it then fell rapidly to baseline within 14 days, while D3 treated people continued to rise to a peak by 14 days, and then stayed high. Armas LA et al, D2 is much less effective than D3 in humans. J Clin Endocrinol Metab 2004;89:5387-91] Abstract/FREE Full Text
It is suggested that this reflects the different affinities of D2 and D3 for the vitamin D binding protein. Also, D2 is broken down more rapidly than D3, and has a shorter shelf-life. One study estimated D2 at 20-40% as efficient as D3 at raising blood CALCIDIOL levels. Trang HM, Cole DE, Rubin LA, Pierratos A, Siu S, Vieth R: Evidence that vitamin D3 increases serum 25-hydroxyvitamin D more efficiently than does vitamin D2. Am J Clin Nutr 1998, 68:854-858. PubMedAbstract | PublisherFullText
Since the drug companies have a license for the use of the patented D2 form of D, expect to find that form in prescription supplements.
Daily Supplemental Dosages of vitamin D3 (preferred to D2)
Due to many factors, vitamin D Dosage is highly individual and the only way to know for sure if you are getting the right amount is to test your blood CALCIDIOL (25(OH)D) level
| Age | Dosage |
| Under 5 | 35 IU/#/day |
| Age 5-10 | 2500 IU |
| Age 18-30 | 5000 IU |
| Pregnant Women | 5000 IU |
( 1 µg vit. D = 40 IU )
The vitamin D council recommends ~ 4000 IU from dietary intake in the absence of UV-B light
- D3 Supplementation increases CALCIDIOL blood level – increasing D3 intake increases the liver’s CALCIDIOL production, boosting the CALCIDIOL blood level. The kidneys and other body cells must produce CALCITRIOL (the active form of vitamin D) from CALCIDIOL. Blood CALCIDIOLlevels do not plateau until after about 3-4 months of consistent supplementation. Vieth R, et al, 2001.
- Under stress or treating disease condition, ensure maximize dosage
- Because vitamin D is fat-soluble, it is better utilized when taken with fat-containing meals
Tanning Bed / Full spectrum lighting
- Tanning increases blood CALCIDIOL levels – a study showed that those who use a full-spectrum tanning bed at least once a week at the end of winter measured healthy blood CALCIDIOL levels of 40-50 ng/ml. Tangpricha V, et al, Tanning is associated with optimal VITAMIN D status and high bone mineral density, Am J Clin Nutr, 2004, 80:1645-1649
- Installing full-spectrum light bulbs in your home or workplace is another way to obtain beneficial UV-B radiation – full-spectrum light bulbs can be ordered from Amazon. Walmart, Home Depot etc
Cofactors required to utilize vitamin D
It is important to realize that vitamins A and D work hand-in-hand. Both protecting and supporting one another. Human studies not taking this into account produce skewed results, and animal studies show that even moderate amounts of vitamin D (from any source)increases the body’s need for vitamin A. Vitamin A will help protect you from an excess of vitamin D. The best food source of vitamin A is beef liver, at least 3-4 oz eaten once per week. Alternatively, take 50,000 units of vitamin A concentrates from fish once or twice a week; Beta-carotene does not provide enough vitamin A to balance vitamin D.
Effectiveness of vitamin D supplementation requires the simultaneous / balanced dietary inclusion of calcium, magnesium, phosphorus, and vitamin K :
- High levels of vitamin D will demineralize bone with insufficient calcium present
- Vitamin D enhances uptake of toxic metals (E.g lead, cadmium, aluminum, strontium) if calcium, magnesium and phosphorus are not present in adequate amounts
You need the right fats for efficient use of vitamin D
- Increasing dietary polyunsaturated and monounsaturated fatty acids decreases the binding of to vitamin D binding proteins – key to both local and peripheral actions of vitamin D. Saturated fats, such as in butter, tallow and coconut oil, do not have this effect. U.S. intake of polyunsaturated oils (from commercial vegetable oils) and monounsaturated oils (from olive oil and canola oil) have dramatically increased, and saturated fat (also supplying varying amounts of D) intake has decreased over the past 100 years, contributing to the current widespread D deficiency.
- Trans fatty acids can interfere with the enzyme systems the body uses to convert vitamin D in the liver –these damaged fats are found in margarine and shortenings (used in most commercial baked goods)
Vitamin D toxicity
VITAMIN D toxicity is considered to exist when one has very high blood levels of vitamin D and calcium AND calcium deposits in soft tissues. Studies on this complex subject are much debated, and it is difficult to draw solid conclusions. To avoid toxicity, it would seem that VITAMIN D levels need to be in the “just right” range, neither too little, nor too much. Evidence also suggests vitamin D toxicity may result from a relative deficiency of vitamins A and K. Symptoms of vitamin D toxemia, such as excessive calcium levels, are not generally observed until CALCIDIOL levels reach ~150 ng/mL. Koutkia P, et al, 2001. Note: Robert Heany reports toxicity at 250 nmol/ L, which is 100 ng / mL, produced from >10,000 IU D / day.
Overdose of vitamin D from the sun is prevented by two inbuilt mechanisms:
- Excess vitamin D produced in the skin by UV-B rays – is further converted to various inactive forms of vitamin D;
- Pigment melanin (i.e. a tan) – begins to accumulate in skin tissues after exposure to UV-A rays, which decreases VITAMIN D production.
Measuring body's vitamin D blood levels
Recommended Testing Lab – Lab Corp in the US; if the test is done by Quest Diagnostics Lab, then divide your result by 1.3 to get the "real" number.
Ng / ml vs. nmol/l -ng / ml are the units of measure in the U.S., However, much of the world uses nmol/l. Test results measured in nmol/l, are multiplied by 2.5 to get ng/ml.
Normal vs. Optimal CALCIDIOL Levels
- The "normal" 25(OH)D lab range is between 20-56 ng/ml. This conventional range is really a sign of deficiency, and is too broad to be ideal. Dark-skinned, tropical agricultural workers typically have blood levels of ~ 60 ng/mL.
- The OPTIMAL value of 25 (OH) D for EVERYONE (children, adolescents, adults and seniors) is 50-65 ng/ml. Your vitamin D level should never be below 32 ng/ml;
- A level below 20 ng/ml is considered seriously deficient – increasing your risk of as many as 16 different cancers, including breast and prostate cancer, and also auto-immune diseases, such as rheumatoid arthritis and MS.
|
25 (OH) D CALCIDIOL LEVELS |
|||
|
Deficient |
Optimal |
With Cancer |
Too High |
|
<50 ng/ml |
50-65 ng/ml |
65-90 ng/ml |
>100 ng/ml |
References
Barger-Lux MJ, Heaney RP, Dowell S, Chen TC, Holick MF: Vitamin D and its major metabolites: serum levels after graded oral dosing in healthy men. Osteoporos Int 1998, 8:222-230. PubMed
