The Vitamin D Debates Continue

I was doing some research on a topic that my brother-in-law, an MD who works in university research, mentioned to me over the holidays. Every time I see this guy, he always gives me ideas! I came across a startling introduction to an article written by John Cannell which I thought I would steal:

What rat poison is safer than water?

The answer is … Vitamin D.

Turns out, there's a lot of new research on this vitamin and, as my brother in law said, the research is indicating that many of us need much more of this vitamin than we are getting. Apparently, vitamin D plays a role in the prevention of much more than just bone loss. Receptors for vitamin D are found in most of the cells of the body. It has been shown to contribute to a healthy immune system, muscle strength and hormone production.

The major function of vitamin D is to maintain normal blood levels of calcium and phosphorus. Vitamin D aids in the absorption of calcium, helping to form and maintain strong bones. Recent research also suggests it may provide protection from osteoporosis, hypertension, heart disease, certain cancers and several autoimmune diseases including diabetes.

But here's speculation that I found really interesting: vitamin D may help in weight control. You might have heard of the study that cites that folks with more calcium in their diets tended to have lower body mass indices (BMI). Well, given that vitamin D is responsible for controlling calcium levels in the blood, it follows that this vitamin plays a role in the high calcium, low BMI phenomenon.

Researchers have also found that obese people have an impaired ability to synthesize vitamin D from sunlight. And, they are looking into the connection between excess calcium deposits in the arteries (cardiovascular disease) and low blood levels of vitamin D. Hmmm..

Vitamin D also plays a role in blood sugar regulation. Swings in blood sugar signal our body's fat storage mechanism and signals our brain to eat or not.

Don't we get vitamin D from sunlight?

Vitamin D is often called the sunshine vitamin because the body synthesizes it from sunlight - specifically, from UV-B rays. Yep, these are the ones we know as the burning rays. In places further from the equator, these rays are most available between 10 am and 2 pm. Most of us avoid spending much time in the sun at these times because we get sunburned which increases our risk of skin cancer and premature skin aging. UV-B rays are blocked well by sunscreens and by glass (glass doesn't block UV-As). Depending on the pigment in your skin, it takes different bodies different amounts of time in the midday sun to get adequate levels of vitamin D. The darker your skin, the more time you need in the sun to get enough of the vitamin.

So, now on to dietary vitamin D: Cod Liver Oil has a lot of vitamin D, followed by some oily fishes, lard (pork fat), butter, dairy fat and egg yolks. Beyond that, it's pretty difficult to get enough of this vitamin from dietary sources alone. So, if you work inside and wear sunscreen, or live at latitudes far from the equator, supplementation may a good thing.

But even supplementation recommendations are now under fire by the researchers. The most common recommendations that I have seen is 400 IU per day for kids, 200 IU per day for adults under 50 years old and 400 IU per day for those over 50. Some researchers are advocating MUCH higher doses – in the 1000 IU to 2000 IU per day range! There is even a lot of debate about toxicity levels of this vitamin among them. Some say more that 2000 IU per day can be toxic, some say 20,000 IU per day is not!

I took a look at my super-duper Women's Multivitamin that I buy at the health food store. It yields 400 IU per day. I am 47 years old, live on the equator where there's lots of UV-B rays much of the day, but work mostly inside and do wear sunscreen every day. So, I have decided to be on the safe side to increase my daily dose of vitamin D supplements to 600-800 IU. This is below what researchers are saying but above recommendations for my age. Remember that when looking at this vitamin, it's important to keep in mind the amount of midday sun exposure you normally get on average, how far you live from the equator, how dark your skin is and how much vitamin D your multivitamin supplies.

Of course, I will keep checking in with my brother in law and published research to keep track of any updates....and will keep you posted.

Sources: The Vitamin D Newsletter 08/20/05. John Cannell http://www.thaifoodandtravel.com/features/vitaminD.html The Micronutrient Information Center, Linus Pauling Institute, Oregon State University. http://lpi.oregonstate.edu/infocenter/vitamins/vitaminD/index.html The Mayo Clinic Newsletter, Drugs and Supplements Section. http://www.mayoclinic.com/health/vitamin-d/NS_patient-vitamind "The Miracle of Vitamin D" by Krispin Sullivan CN. http://www.westonaprice.org/basicnutrition/vitamindmiracle.html

Copyright (c) 2007 Ainsley Laing

Are you getting enough Vitamin D? What is enough Vitamin D? Research is fueling many debates.

About the Author: Ainsley Laing, MSc. has been a Fitness Trainer for 25 years and writes exclusively Body for Mind eZine. She holds certifications in Group Exercise, Sports Nutrition and Personal Fitness Training. To see more articles by Ainsley visit http://www.bodyformind.com

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