Dr. Davis,
As cholesterol in the skin is a precurser to Vitamin D, it makes sense that there'd be a seasonal fluctuation in circulating cholesterol.  In summer months, with skin exposure, the cholesterol in the skin is being converted and "used" and more has to come from the rest of the body to take it's place. Couldn't that naturally draw down the serum choesterol levels?

Zuleika's Vitamin D Experiment shows data from http://www.anaboliclabs.com/company_main/PDFS/Vit%20D%20telecon%20-%20Jan%202007.pdf

January 2007

Deficiency <50 nmol/L
Insufficiency 50-80 nmol/L
Optimal 80-250 nmol/L
Excess/Tox: >250 nmol/L

Great thought. It would make sense.

I'm uncertain if the quantity of cholesterol taken for conversion of inactive to active vitamin D in the skin is sufficient impact on blood levels. It will be interesting to see how this argument unfolds as the vitamin D experience grows worldwide.

Perhaps vitamin D raises HDL by improving glucose metabolism. There are vitamin D receptors in pancreatic beta cells, and vitamin D deficiency has been shown to impair insulin synthesis and secretion in humans and in animal models [1]. Vitamin D supplementation in women with type 2 diabetes increased first phase insulin secretion, and also reduced insulin resistance, though not significantly [2].

1. Mathieu C, Gysemans C, Giulietti A, Bouillon R. Vitamin D and diabetes. Diabetologia. 2005 Jul;48(7):1247-57. Epub 2005 Jun 22.

2. Borissova AM, Tankova T, Kirilov G, Dakovska L, Kovacheva R. The effect of vitamin D3 on insulin secretion and peripheral insulin sensitivity in type 2 diabetic patients. Int J Clin Pract. 2003 May;57(4):258-61.

I'm going to a new doc soon and want to have my vit d levels checked. I've been taking supplements and want to find out my level.

What test do I ask for? Is it just a blood level? or is there more to it?

I also am going to ask for CRP, hemocystine and ferritin in addition to all the normal labs for a 53 yr old woman.

I'm also concerned about the cholesterol testing. My levels are high, and I reacted badly to statins. What's the best thing to ask for with the cholesterol tests. I'm in the Duke system, so I'm sure almost everything is available, but can't afford anything that insurance won't cover.

Cindy--
Ask for a 25-OH-vitamin D3 level. Be certain it is NOT a 1,25-diOH-vitamin D3. They sound and look the same but are very different. The second is a measure of kidney function. Only the 25-OH form serves as a measure of vitamin D.

We suggest an NMR lipoprotein profile with lipoprotein(a), C-reactive protein, glucose, insulin, homocysteine (though you'll get some resistance on this one).

Dr. Davis

What about the seasonal differences of diet and physical activity on total cholesterol? Our winter and fall diets are heavier with foods that raise cholesterol whereas in the warmer spring and summer we tend to eat lighter and maybe more salads and fruits.  And the warmer weather of spring and summer also makes us more active, going outdoors for walks, working on our yards, going to the beach, etc.

I’ve seen it happen over and over. It doens't occur in everybody but occurs with such frequency that it’s hard to ignore or attribute to something else. What I’m not clear about is whether this effect only occurs in the presence of the other strategies we use to raise HDL, a “facilitating” effect, or whether this is an independent benefit of HDL that would occur regardless of whatever else you do. Time will help clarify.

Wonderful!  

Unless they have some particular questions, I suspect that many regular readers of your blog wouldn't need a consultation with you, as they're already pretty well-informed and/or in good health.

However, I can see that someone's less-informed mother, father, friend, or whatnot might benefit hugely from such a consultation.  It might make a great gift for Mother's Day or Father's Day!

you should also give your email ID and some weekly diet plan to be sent through email

The Video Teleconference is not meant to replace the opinion of your doctor, nor diagnose or treat any condition. It is simply meant to provide additional discussion about your health issues that should be discussed further with your healthcare provider. Prescriptions cannot be provided.

I's a good ideea.

But, can't we get ample vit.D3 from sun exposure? I'm nursing my second infant, and rather than supplemetning her with vit D, since breastmilk doesn't contain vit d, I expose her to sunlight often, for a few minutes at a time to prevent rickets. Why does anyone need vit D supplements in our food etc when it can be gotten for free in the sun?

Less than 1 in 20 people have sufficient vitamin D blood levels when they are checked in Wisconsin and other northern climates. Studies suggest that between 30-50% are deficient in southern or tropical climates, such as Florida and Hawaii. There are many racial and other reasons for this, but mostly it has to do with wearing clothes and living indoors. The only way to be certain is to have a blood level checked.

Soundhunter...breastmilk isn't deficient in vitamin d per se, it's deficient if the mother is deficient - so it's important you consume enough vitamin d in your diet (or supplements) and/or get enough exposure to sunlight.  One good source in the winter months is cod liver oil....vitamin d is also found in natural cheeses (with higher amounts in grass-fed, alpine cheese), eggs (in the yolk) and tuna in oil (as well as other fatty fish).

And what happen with people who are allergic to lactose there are substitutes for that?Generic Viagra  Buy Viagra

You'll note that the only naturally-occurring food sources of vitamin D are the modest quantities in fish, egg yolks, and liver. All the other vitamin D-containing foods like cereal, milk, and other dairy products have vitamin D only because humans add it.