Are You Absorbing Your Vitamin D?

By Ruth Ann Clayton, RD

An article, Dietary Fat Increases Vitamin D-3 Absorption, in the Journal of The Academy of Nutrition and Dietetics caught my eye recently.   This is what I always tell everyone about how to get the most benefit from fat soluble Vitamin D when taking it in supplement form.  It is always pleasing to see more research back this up.

Research helps you know when you are on the right road to getting the most benefit from your nutrients.  As Vitamin D deficiency is a real concern the more you know the better.

Here is a quick refresher on Vitamin D.  It is actually a vitamin/hormone.  If your skin is exposed to the sun Vitamin D is produced and sent to the liver which changes it into 25-hydroxyvitaminD or 25(OH)D. No other vitamin can be produced in this way.  As lifestyles have changed, so have Vitamin D levels.  When your doctor checks your Vitamin D levels he is measuring 25(OH)D in your blood.

Regular sun exposure is a must.  With less sun time and cloudy winter day’s exposure to the sun’s UVB rays is slim. This is the number one reason to take Vitamin D supplements.  Also rates of the metabolism of vitamin D may differ from one individual to another.

Vitamin D from food is absorbed in the gut and also sent to the liver for conversion.   Few foods provide us with Vitamin D-3, (cholecalciferol) and D-2 (ergocalciferol).  D-3 is found in cod liver oil, salmon, mackerel, sardines, and tuna.    Fortified foods provide only a small amount of D-3.    D-2, from plants is thought to be less effective.

This nutrient is a building block in the body.  Its contribution to health is staggering.  The benefits include supporting the brain, bones, blood calcium levels, heart, immunity, and much more. It also has the great task of regulating a vast number of human genes.

Vitamin D deficiency is common and the typical diet is usually insufficient in making up any shortfalls. Have your Vitamin D levels checked.  If levels are low your doctor will tell you how much and how long to take supplementation. A maintenance dose can keep blood levels adequate.

The Tufts University School of Medicine study mentioned above was testing the hypotheses that Vitamin D is absorbed better when taken with a meal containing fat versus a fat-free meal.  The results were conclusive that Vitamin D absorption is enhanced by the presence of fat in a meal.  The type of fat did not influence absorption.

What is the take home lesson? You will have better absorption and higher blood levels of 25(OH)D when you take your vitamin D-3 supplement with a meal containing fat.  Better absorption enables you to get more benefits from this valuable key to health.

Ruth Ann Clayton is the Registered Dietitian at Nature’s Way.  She has been featured in and interviewed by nationally published trade journals.   Reach her at  This information is not intended to diagnose, treat, or cure any disease.

Ruth Ann Clayton, Registered Dietitian, is active in both the American Dietetics Association and Dietitians in Integrative and Functional Medicine Dietetic Practice Group. Her nationally accredited Dietetic Internship and her years of experience in public health and hospital settings reflect her commitment to your health and well being.

As the co-owner of Nature’s Way, she uses her comprehensive background to research products, read labels, investigate manufacturers and provide information for her customers.