Q & A Library

Print this page | Sign up for free e-bulletins
 | Bookmark This Page

Vitamin D Deficient?

My oncologist told me that I am severely vitamin D deficient, and has prescribed 50,000 IU once a week for 4 weeks, and then every other week for 6 months. What causes this deficiency? 

Answer (Published 2/8/2010)

You're not alone. Most adults in the United States are not getting enough vitamin D, which we need for bone health. In addition, more and more research suggests we need this hormone for protection against a number of serious diseases, including many types of cancer. The principal reason for widespread deficiencies in vitamin D is not spending enough time in the sun. Our bodies synthesize vitamin D with exposure to sunlight, but it's tough to get optimal exposure, particularly in northern latitudes during the dark winter months. If you live north of the latitude of Atlanta, Georgia, the sun is not high enough in the sky half of the year to stimulate vitamin D production in the skin. Even in southern Arizona, where I live, vitamin D deficiency is common because dermatologists have made everyone so paranoid about sun exposure that most people here use sunscreen all the time, and sunscreen blocks vitamin D synthesis. What's more, the older you get, the greater the risk of vitamin D deficiency. With advancing age, the skin cannot synthesize vitamin D as efficiently as it once did and the kidneys are less able to convert vitamin D to its active hormone form.

Related Weil Products
Dr. Weil's Vitamin Advisor for Supplements & Herbs - If you are interested in supplementing your diet, and want to take the mystery out of choosing vitamins, try Dr. Weil's Vitamin Advisor. Visit today for your free, personalized Dr. Weil's Vitamin Advisor Recommendation.

It also isn't easy to get enough D from your diet. The best sources are fortified milk and cereals, eggs, salmon, tuna, mackerel and sardines. (Unfortunately, most fortified foods provide vitamin D2, a form which is less well utilized by the body than the D3 you make with sun exposure.)

For all these reasons, I recommend that everyone take 2,000 IU a day of vitamin D3. Although current methods don't always yield accurate results, I also recommend that everyone get their vitamin D level tested. Look for results in the normal range, from 30.0 to 74.0 nanograms of 25-hydroxy vitamin D per milliliter (ng/mL) of blood. (Normal value ranges may vary slightly among different labs.)

Treatment for a vitamin D deficiency is 50,000 IU of vitamin D per week, usually for eight weeks, followed by 50,000 IU once or twice per month thereafter.

Andrew Weil, M.D.

Creative Commons License Some Rights Reserved Creative Commons Copyright Notice
A portion of the original material created by Weil Lifestyle on (specifically, all question and answer-type articles in the Dr. Weil Q&A Library) is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License.

The Weil Vitamin Advisor
Get your FREE personalized vitamin recommendation & supplement plan today!

Dr. Weil on Healthy Aging
Your Online Guide to the Anti-Inflammatory Diet. Start eating for your health - begin your free trial now.

Dr. Weil's Spontaneous Happiness
Achieve emotional well-being
in just eight weeks!
Start your 10-day free trial now!

Vitamin Library
Supplement your knowledge with Dr. Weil's essential vitamin facts. Learn why they are necessary and more.

Dr. Weil's Optimum Health Plan
Your 8-week plan to wellness.
Begin your journey today!

Dr. Weil's Head-to-Toe
Wellness Guide

Your guide to natural health.
Use the Wellness Guide today!

Dr. Weil's Anti-Inflammatory Diet Food Pyramid
Our interactive tool can help improve overall health through diet.

Condition Care Guide
Learn about health conditions from acne to vertigo, and Dr. Weil's view of the best treatment options for each.

Healthy Recipes
Discover a treasure trove of healthy, healing foods and creative, delicious ways to prepare them.

Q&A Library
Over 2,000 questions from you
and their corresponding answers
from Dr. Weil.

Copyright © 2015 Weil Lifestyle
Information on this web site is provided for informational purposes only and is not intended as a substitute for the advice provided by your physician or other healthcare professional. You should not use the information on this web site for diagnosing or treating a health problem or disease, or prescribing any medication or other treatment.

Ad Choice
Advertising Notice

This Site and third parties who place advertisements on this Site may collect and use information about your visits to this Site and other websites in order to provide advertisements about goods and services of interest to you. If you would like to obtain more information about these advertising practices and to make choices about online behavioral advertising, please click here