When you research, read, and watch the news as much as I do, you can see the new nutrient and supplement trends coming a mile away. Sometimes they’re valid, other times they aren’t. I can say for certain to buckle up and hop on the D-train because it’s here to stay. In fact, this isn’t a newly found miracle baby; this is an age old savior that we’ve been neglecting.
What is Vitamin D?
Vitamin D is a fat soluble steroid hormone (and if we weren’t playing fast and loose with the terminology, it technically isn’t a vitamin at all). The main job of vitamin D is to maintain normal blood levels of calcium and phosphorus. Note that’s the main job. It’s said that over 200 genes are affected by vitamin D. It doesn’t matter where you turn, its uses are everywhere. Bone, heart, insulin, depression, pain, happiness, cancer, fibromyalgia, thyroid… you name it, vitamin D plays a role.
Michael F. Holick, a leading researcher on the importance of vitamin D, has said that “Vitamin D deficiency is the disease of neglect.”
And he couldn’t be more right.
The cure for rickets — a widespread epidemic in the children of the softening of the bones — was found by sticking children on the roof of a building. Can you sit there and take that in for a moment? An illness that was making the limbs of children turn into mush was cured by the sun.
You may wonder what this has to do with you, but bones should be your pride and joy. Not to mention the fact that recent studies show an alarming rate of newborns and mothers are becoming more and more deficient. Are past problems coming back to bite us in our vitamin-deficient rears?
Beyond just bones, being too low in vitamin D can lead to a decrease in thyroid function. Although not directly involved in synthesis or secretion, a deficiency can produce increases in the levels of parathyroid hormone.
On the wellbeing side, an increased occurrence of depression and a decrease in mental focus have been found time and time again. There are also links that have shown women who supplement with vitamin D may lose fat easier than those who don’t.
Currently, the desired levels are 30 to 75 ng/mL-nmol/L, and anything less is seen as deficient, though higher doesn’t necessary mean you’re at a toxic level. The concern is for consistent levels above the 200 range.
The bottom-out number should really be 30; however, we’re seeing study after study show that levels are constantly hitting below this all around the world, and the aftereffect is becoming an epidemic.
| ng/mL | nmol/L | Status |
| <> | <> | These levels suggest severe illness, usually seen in rickets or sick infants. |
| <> | <> | While not directly or instantly crippling, these levels overtime may contribute to illness both acute and chronic. |
| ≥ 30 | ≥ 75 | Seen by some to be the desired range and achieving of optimal health. |
| Consistently > 200 | Consistently > 500 | Could be toxic and lead to hypercalcemia and hyperphosphatemia. |
Serum 25-hydroxyvitamin D [25(OH)D] concentrations and health
How Do You Get It?
Vitamin D is the “sun vitamin,” meaning that you should receive 80 to 100% of your intake from the sun. When ultraviolet (UV) rays hit the skin, they’re absorbed and converted, setting into motion your body’s process of creating vitamin D. In truth, this should be the end all for receiving your daily intake.
However, things just aren’t that simple.
What About Food Intake?
Vitamin D can be found in small amounts in certain fishes, fortified milks, and egg yolks.
The problem is that the intake would have to consist of very high levels and multiple times daily to give you the effects you need. It also would depend on the quality of your food. With fish, for instance, it’s been shown that farmed salmon (fish raised in tiny boxes eating crappy fish food) held at least 25% less vitamin D than wild-caught salmon.(1)
Take-home point being, if you think that the Wal-Mart fish nutrients are doing something for you, think again. What they eat is what you eat. As well, the fortified milk and cereal claims of vitamin D can be off by as much as 80% of what the label says.
Here’s a chart that gives you a general rundown of food sources for vitamin D:
| Food | IU per serving | Percent DV |
| Cod liver oil, 1 tablespoon | 1,360 | 340 |
| Salmon, cooked, 3.5 ounces | 360 | 90 |
| Mackerel, cooked, 3.5 ounces | 345 | 90 |
| Tuna fish, canned in oil, 3 ounces | 200 | 50 |
| Sardines, canned in oil, drained, 1.75 ounces | 250 | 70 |
| Milk, nonfat, reduced fat, and whole, vitamin D-fortified, 1 cup | 98 | 25 |
| Margarine, fortified, 1 tablespoon | 60 | 15 |
| Ready-to-eat cereal, fortified with 10% of the DV for vitamin D, 0.75-1 cup (more heavily fortified cereals might provide more of the DV) | 40 | 10 |
| Egg, 1 whole (vitamin D is found in yolk) | 20 | 6 |
| Liver, beef, cooked, 3.5 ounces | 15 | 4 |
| Cheese, Swiss, 1 ounce | 12 | 4 |
Selected food sources of vitamin D (2,3)
Differences in Vitamin D
Vitamin D comes in two main forms: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). There’s a D1, D3, and D5, but in short, their importance and our control of them isn’t the main topic here.
Vitamin D2 is made by the UV irradiation of ergosterol in yeast, and vitamin D3 is made by the irradiation of 7-dehydrocholesterol from lanolin and the chemical conversion of cholesterol.
It’s suggested that D3 is far superior to D2 at raising levels in the body and holding them higher for extended periods of time.(4,5) Because of this, if you’re going the supplement route for your intake of vitamin D, D3 is the winner of the group.
The overall goal of vitamin D is to raise serum levels in the body and do so as best as possible. To date, both D2 and D3 supplements at prescription-grade levels have shown to do this. D2, however, has been shown to be toxic at higher levels. (It should be noted that you can’t achieve toxic levels of D in the body with just the sun.)
How Long is Too Long in the Sun?
This is the tricky part and most often misunderstood. Obviously, there’s plenty of data to back up that being in the sun too long without protection can lead to skin cancers. The flipside is that being in the sun too little might lead to cancer as well.
You may think that applying some sunscreen will get you the best of both worlds, but sadly sunscreen has been shown to block upwards to 95% of vitamin D uptake from the sun.(6)
What are you to do?
A good solution is to spend fifteen minutes in the sun and then apply your sunscreen. It’s suggested that fifteen minutes a day can be enough. However, for a lot, that isn’t the case. And unless you’re living below 42 degrees North latitude (a line approximately between the northern border of California and Boston), in the wintertime you aren’t going to get it at all.(7)
Studies also show that if you’re African America or Hispanic then you need near double what Caucasians need.(8,9)
The Do’s and Don’ts of Vitamin D
If you find yourself stuck inside, above the magic line, or of darker skin, then you might need to look at better options of getting vitamin D.
1. Don’t be obese: Obesity blocks vitamin D intake by as much as 55%.
2. Don’t be scared of the sun: We’re a culture of extremes and look at where it’s got us. You need some sun, so don’t be afraid of it. Just call it quits before you burn like a lobster.
3. Do eat cod liver oil: Cod liver oil in supplement form is a really simple and easy way to get in lots of D3 during those months when you may not be able to.
4. Don’t be scared of the tanning bed: If you’ve ever known a friend with an iguana or turtle, then you know that in order to survive they need those ultraviolet exposures. Well, so do you!
Exposure to tanning beds resulted in a 100% increase in blood concentrations of vitamin D.(10) The problem is, just as with the sun, people take things too far. It’s a great way to get what you need in the winter months, but the same “don’t overdo it” rules apply.
5. Do get tested: In general, you should be getting a full vitamin and mineral testing every six months. Is it time for a checkup?
6. Do hit the numbers: While 400 IU is the recommend dosage, there’s nothing wrong with getting 1,000 IU, especially from D3, and namely during the “off season.”
7. Do take this seriously: I’m not usually one for dramatics, but there are so many low level health problems that can lead to higher level problems, and issues from a vitamin D deficiency can be really simple to solve.
Take it seriously; get in your sun, get in your oils, and take advantage of the problems you can fix every chance you get.
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References
1. An evaluation of the vitamin D3 content in fish: Is the vitamin D content adequate to satisfy the dietary requirement for vitamin D?
2. Nutrition Coordinating Center. Nutrition Data System for Research (NDS-R). Version 4.06/34. Minneapolis: University of Minnesota, 2003.
3. U.S. Department of Agriculture, Agricultural Research Service. USDA Nutrient Database for Standard Reference, Release 16. Nutrient Data Laboratory Home Page, 2003.
4. Houghton LA, Vieth R. The case against ergocalciferol (vitamin D2) as a vitamin supplement. Am J Clin Nutr 2006;84:694-7.
5. Nesby-O’Dell S, Scanlon KS, Cogswell ME, Gillespie C, Hollis BW, Looker AC, et al. Hypovitaminosis D prevalence and determinants among African-American and white women of reproductive age: third National Health and Nutrition Examination Survey, 1988-1994. Am J Clin Nutr 2002;76:187-92.
6. http://www.ajcn.org/cgi/reprint/80/6/1678S.pdf
7. Cranney C, Horsely T, O’Donnell S, Weiler H, Ooi D, Atkinson S, et al. Effectiveness and safety of vitamin D. Evidence Report/Technology Assessment No. 158 prepared by the University of Ottawa Evidence-based Practice Center under Contract No. 290-02.0021. AHRQ Publication No. 07-E013. Rockville, MD: Agency for Healthcare Research and Quality, 2007.
8. Nesby-O’Dell S, Scanlon KS, Cogswell ME, Gillespie C, Hollis BW, Looker AC, et al. Hypovitaminosis D prevalence and determinants among African-American and white women of reproductive age: third National Health and Nutrition Examination Survey, 1988-1994. Am J Clin Nutr 2002;76:187-92.
9. Yetley EA. Assessing vitamin D status of the U.S. population. Am J Clin Nutr. In press.
10. Holick, M. F. (2004). Vitamin D: importance in the prevention of cancers, type 1 diabetes, heart disease, and osteoporosis. American Journal of Clinical Nutrition, 79, 362-371.
Source: http://avidityfitness.net/2008/10/13/vitamin-d-the-real-factstruths-and-sources-of-the-sun-vitamin/
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