Vitamin D levels: Sunlight, age, and toxicity

Calcidiol is a pre-hormone that is produced based on vitamin D3 in the liver. Blood concentration of calcidiol is considered to be a reliable indicator of vitamin D status. In the research literature, calcidiol is usually referred to as 25-Hydroxyvitamin or 25(OH)D. Calcidiol is converted in the kidneys into calcitriol, which is the active form of vitamin D.

The table below (from: Vieth, 1999; full reference at the end of this post; click on it to enlarge), shows the average blood vitamin D levels of people living or working in sun-rich environments. To convert from nmol/L to ng/mL, divide by 2.496. For example, 100 nmol/L = 100 / 2.496 ng/mL = 40.1 ng/mL. At the time of this writing, Vieth (1999) had 692 citations on Google Scholar, and probably more than that on Web of Science. This article has had, and continues having, a high impact among researchers.

The maximum average level of blood (or serum) vitamin D shown in the table is 163 nmol/L (65 ng/mL). Given that the human body produces vitamin D naturally from sunlight, it is reasonable to assume that those blood vitamin D levels are not yet at the toxic range. In fact, one of the individuals, a farmer in Puerto Rico, had a level of 225 nmol/L (90 ng/mL). That individual had no signs of toxicity.

Several studies show that pre-sunburn full-body exposure to sunlight is equivalent to an oral vitamin D intake of approximately 250 µg (10,000 IU).

In spite of claims to the contrary, vitamin D production based on sunlight does not cease after 40 years of age or so. Studies reviewed by Vieth suggest that among the elderly (i.e., those aged 65 or above) pre-sunburn full-body exposure to sunlight is equivalent to an oral vitamin D intake of 218 µg (8,700 IU).

Sunlight-induced vitamin D production does seem to decrease with age, but not dramatically.

Post-sunburn sunlight exposure does not increase vitamin D production. Since each person is different, a good rule of thumb to estimate the number of minutes of sunlight exposure needed to maximize vitamin D production is the number of minutes preceding sunburn. For a light-skinned person, this can be as little as 7 minutes.

Vitamin D accumulation in the body follows a battery-like pattern, increasing and decreasing gradually. The figure below, from Vieth’s article, shows the gradual increase in blood vitamin D concentrations following the start of daily supplementation. This suggests that levels start to plateau at around 1 month, with higher levels reaching a plateau after 2 months.

While sunlight exposure does not lead to toxic levels of vitamin D, oral intake may. Below is a figure, also from Vieth’s article, that plots blood levels of vitamin D against oral intake amounts. The X’s indicate points at which intoxication symptoms were observed. While typically intoxication starts at the 50,000 IU intake level, one individual displayed signs of intoxication at 10,000 IU. That individual received a megadose that was supposed to provide vitamin D for an extended period of time.

Non-toxic levels of 10,000 IU are achieved naturally through sunlight exposure. This applies to modern humans and probably our Paleolithic ancestors. Yet, modern humans normally limit their sun exposure and intake of vitamin D to levels (400 IU) that are only effective to avoid osteomalacia, the softening of the bones due to poor mineralization.

Very likely the natural production of 10,000 IU based on sunlight was adaptive in our evolutionary past, and also necessary for good health today. This is consistent with the many reports of diseases associated with chronic vitamin D deficiency, even at levels that avoid osteomalacia. Among those diseases are: hypertension, tuberculosis, various types of cancer, gingivitis, multiple sclerosis, chronic inflammation, seasonal affective disorder, and premature senescence.

Reference:

Reinhold Vieth (May 1999). Vitamin D supplementation, 25-hydroxyvitamin D concentrations, and safety. American Journal of Clinical Nutrition, Vol. 69, No. 5, 842-856.

Healthy Spirits: New Arrivals! Tyttebaer, Haandbakk and more!

Hey dudes.

Hope everybody is preparing themselves for beer week. Don't forget to check out 21st Amendment and Magnolia all month long for their strong beer releases! Last year's releases were fantastic, and I can only assume this year's are going to be even better. Anyway, here's the new stuff:

1. Haandbryggeriet Haandbakk (Vintage 2008)

2. Haandbryggeriet Wild Thing

3. Nogne-O Tyttebaer (collaboration with Mikkeller)

cheers,

dave hauslein

beer manager

415-255-0610

How much vitamin D? Vitamin D Council's recommendations

Since my recent post on problems related to vitamin D deficiency and excess I received several questions. I have also participated in several discussions in other blogs related to vitamin D in the past few days.

There is a lot of consensus about vitamin D deficiency being a problem, but not much about vitamin D in excess being a problem as well.

Some bloggers recommend a lot of supplementation, which may be dangerous because: (a) our body evolved to obtain most of its vitamin D from a combination of sunlight exposure and cholesterol, and thus body accumulation regulation mechanisms are not designed to deal with excessive oral supplementation; and (b) vitamin D, like many fat-soluble vitamins, accumulates in fat tissue over time, and is not easily eliminated by the body when in excess.

The Vitamin D Council has the following general recommendation regarding supplementation:

Take an average of 5,000 IU a day, year-round, if you have some sun exposure. If you have little, or no, sun exposure you will need to take at least 5,000 IU per day. How much more depends on your latitude of residence, skin pigmentation, and body weight. Generally speaking, the further you live away from the equator, the darker your skin, and/or the more you weigh, the more you will have to take to maintain healthy blood levels.

They also provide a specific example:

For example, Dr. Cannell lives at latitude 32 degrees, weighs 220 pounds, and has fair skin. In the late fall and winter he takes 5,000 IU per day. In the early fall and spring he takes 2,000 IU per day. In the summer he regularly sunbathes for a few minutes most days and thus takes no vitamin D on those days in the summer.

For those who have problems with supplementation, here is what Dr. Cannell, President of the Vitamin D Council, has to say:

For people who have trouble with supplements, I recommend sunbathing during the warmer months and sun tanning parlors in the colder months. Yes, sun tanning parlors make vitamin D, the most is made by the older type beds. Another possibility is a Sperti vitamin D lamp.

One thing to bear in mind is that if your diet is rich in refined carbohydrates and sugars, you need to change that before you are able to properly manage your vitamin D levels. You need to remove refined carbohydrates and sugars from your diet. No more white bread, bagels, doughnuts, table sugar, sodas sweetened with high-fructose corn syrup; just to name a few of the main culprits.

In fact, a diet rich in refined carbohydrates and sugars, in and of itself, may be one of the reasons of a person''s vitamin D deficiency in the case of appropriate sunlight exposure or dietary intake, and even of excessive levels of vitamin D accumulating in the body in the case of heavy supplementation.

The hormonal responses induced by a diet  rich in  refined carbohydrates and sugars promote fat deposition and, at the same time, prevent fat degradation. That is, you tend to put on body fat easily, and you tend to have trouble burning that fat.

This causes a "hoarding" effect which leads to an increase in vitamin D stored in the body, and at the same time reduces the levels of vitamin D in circulation. This is because vitamin D is stored in body fat tissue, and has a long half-life, which means that it accumulates (as in a battery) and then slowly gets released into the bloodstream for use, as body fat is used as a source of energy.

It should not be a big surprise that vitamin D deficiency problems correlate strongly with problems associated with heavy consumption of refined carbohydrates and sugars. Both lead to symptoms that are eerily similar; several of which are the symptoms of the metabolic syndrome.

New Arrival: Supplication is here!

Supplication has finally arrived, this years release comes in 375ml bottles and is a blend of beer aged 12 and 15 months in Pinot Noir Barrels. You want this!




Come and get it


Nate

Roasted Veggies & Linguine with Optional Chicken

I found the original recipe for this in my Vegetarian Times Magazine this month, but I adapted it a bit and added some "optional chicken" for some protein. In the magazines Valentine's addition they recommended making this dish for the official LOVE Day because it brings the fire (with the red pepper flakes) and the romance (with the white wine), so make it for someone you love... or for yourself- you'll love it too!

Ingredients:

Grape Seed Oil (or Olive Oil)

2 cups mushrooms, sliced

1 bunch asparagus, chopped in 2 inch pieces

1 small onion, coarsely chopped

2 TBSP grape seed oil

2 cloves garlic, minced

1/4 tsp red pepper flakes

2 cups cherry tomatoes

1/2 cup white wine

1/4 cup chicken broth

1/2 cup basil, torn * optional, can make it without

pasta, whole wheat or brown rice ( I used 1/2 a package of Trader Joe's Whole Wheat Linguini)

Directions:

Pretty easy recipe, room for sloppy measuring and variations, so feel free to use what you have on hand and modify where you need to. First, bring your water to boil for your pasta and cook noodles per directions on the pasta package. Next, chop your asparagus, onion, and mushrooms and toss them in a bowl with some Grape Seed oil and red pepper flakes. (the original recipe called for 1/2 tsp pepper flakes, so if you like it hot, add more- I thought it was plenty spicy with 1/4 tsp). Spread the veggies on a roasting pan lined with parchment paper and bake at 400 for 12 minutes. Then add the tomatoes to the pan and let them roast for another 7-9 minutes until veggies get to your preference (the tomatoes will burst open and start to shrivel). Remove them and scoop them into a bowl. If you choose to add chicken, add some grape seed oil and a garlic clove to a frying pan and brown some chicken tenders. Remove them from the pan, and cut them into bit size pieces. Then drain the pasta and add to the bowl with the veggies and the chicken. Add everything pack to your frying pan, pour your wine and chicken broth in and use some s & p, mix everything up and let simmer for a 5 minutes, turning frequently to mesh all the juices and flavor. Serve up solo!

Healthy Spirits: Rated 27th best beer store in the world!

Healthy Spirits has placed 27th on Ratebeer's 2010 list of the best beer stores in THE WORLD. We're just that good. Thank you to all our supporters on Ratebeer, as well as all the other great online beer sites.

Here's a YouTube video made by Winton (a regular). It's a great overview of some of the top beer spots in the city.

http://www.youtube.com/watch?v=3QrFgp7gQrQ

Sauteed Mushrooms & Chicken

In a pinch for dinner one night I combined some ingredients I had on hand- it was yummy, fast, and required very little prep. Use it the next time your in a pinch!

Ingredients:

1/2 red onion

2 cloves garlic

1 TBSP parsley

1 package chicken tenders

1/2 cup white wine or sherry wine

1 package mushrooms, I used crimini

Directions:

First I sauteed the red onion and garlic in a drizzle of grape seed oil for about 2 minutes. Then I added my sliced mushrooms and 1/4 cup of white wine and let them saute for another 3-4 minutes (you could go wild and add a TBSP of butter if you wanted!). I then removed them from my pan onto a dish, and added another drizzle of grape seed oil that coated my pan along with the remains from the mushrooms. I added my chicken tenders, and let them brown on one side, turned them and browned them on the other side. Once they were fully cooked, I added another 1/4 cup of white wine to my pan and then added back the dish of mushrooms, and let them cook together for about 2 minutes, stirring them all together. I served it over a bed of brown rice pasta, but you could serve it over a bed of stemmed veggies or brown rice too!