Re: Lack of Vitamin D - The Real Reason Flu Hits In Winter

Thanks to Adeha, for these comprehensive and important comments regarding the Lack of Vitamin D - The Real Reason Flu Hits In Winter post. Natural Vit D from foods is metabolized differently than that found in supplements. Often Vit D in Cod Liver Oil is synthetic as the natural variety is destroyed from the processing. Obviously all good things need to used sensibly. This is a must read!

Chris Gupta

Hi Chris,

I'm also very impressed with the potential benefits of vitamin D supplementation, but I understand there are caveats. If you get too much, the consequences are serious. Krispin Sullivan, CN, has been researching vitamin D for years and has written a book, Naked at Noon, that is just about to be published. She has found that, while many people are very vitamin D deficient, some are not, and supplementation for those that are not deficient disturbs calcium metabolism, and can be very dangerous. Dr. Mercola was also very enthusiastic about vitamin D supplementation. However, through personal experience, he discovered it's easy to get too much, both from cod liver oil and from supplementation. Mercola is now very clear that testing is critical if you want to reap the benefits of vitamin D supplementation. Krispin lives in Ca, where people get varying amounts of sun. Mercola lives in Chicago, where there is practically no UVB in the winter. Most of his patients were severely deficient, and for awhile he was recommending high dosages for everybody. Then he found his own blood levels of D skyrocketed when he went south to the sun after doing long term cod liver oil supplementation. How much sun you get is critical, and how much UVB is in the sun you get is also critical. Another factor is the color of your skin. Dark skined people need 10 times more sun to make vitamin D, so are almost always deficient if they live out of the tropics. Each person's situation is different. The upshot is, for supplementation higher than 800-1000 iu, testing is critical! Sullivan's web article, Miracle of Vitamin D, and the website excerpt below give some idea of the complexity of the subject and how to supplement safely.

All the best,

For Krispin's fascinating introduction to the topic, please read The Miracle of Vitamin D at 

Below is an excerpt from Krispin's site that explains some of her concerns about high dose supplementation. Folks can order a relatively inexpensive blood test for vitamin D at

Sample Question: Do I have to worry about not getting enough UV-B exposure (for Vitamin D), during the winter, since I live in Denver, which, obviously is 5,280 above sea level?   I apologize for  bothering you, but, I could not find this answer anywhere on the Internet.  Obviously this answer will make a big difference on how much Vitamin D supplements I need to take.

The Answer: Yes and no. Each 1,000 feet in elevation equals about 1 degree closer to the equator (from where you are) so Denver, latitude 39.46? at altitude 5,280 ft would have a similar UV-B to a location at 33-34?, not all that UV-B rich. Reflective snow in winter would make mid-day more intense but as to available D it just isn't all that much because UV-B is less in winter in all locations more distant from the equator. Only locations 30? or closer to the equator have consistently intense UV-B.

Any supplemental D should not be based on location because your need for D depends on much more than that; your skin color, your age, your sunning habits, your diet, your genes, your weather (clouds, fog and some urban pollution, aka urban ozone, block UV-B). The only way to know how much D you have and how much D or sun you need and if the D or sun you are using is working is TESTING.

The book, Naked at Noon, does not contain detailed instructions on how to maximize vitamin D safely. For all vitamin D enthusiasts- Please do not take D in amounts larger than 800 IU daily from all sources (including sun exposure) without clinical testing, physician guidance, and continuing support. Read the excerpts from the book. If you believe you need more D please order the Preliminary Report, see below, to make sure you are using D safely.

Harm can occur from excess D as well as insufficiency. Taking D when it is not needed is potentially dangerous no matter what form of D you may be taking.  Do not self treat.

Various websites and 'experts' state high doses of A and D are safe. The information on which this suggestion (not fact, not science) is based is faulty information (including the references and links to a particular vitamin D 'foundation' where you will find more faulty information). The references being presented are based on illogically conceived and executed research published with unsupportable conclusions.  A primary focus of my book is a review of research  which shows  that studies being cited as the basis for claiming high doses of vitamin D are safe were wrong when they were first published. The conclusions drawn by the 'safe vitamin D' research proponents (including the researchers themselves) overlook major flaws in the studies. To mention just one of the flaws (there are many), no study has been done using high dose vitamin D for longer than 6 months. D toxicity (or, for that matter, vitamin A toxicity) may take a year or longer to develop putting the trusting user (victim) at great risk.

For an overview of why caution is advised do read the book excerpts, and  Caution- Living Systems are Complex Systems.

I would say from experience most benefit from extra D, especially D from sunlight, but we are all individuals and what is right for one may not be right for another.

Enthusiastic promoters of 'natural' vitamin D or cod liver oil suggest that, as it is natural, it is safe in high amounts. Some 'experts' use references to 'prove' their claims. These references are outdated, not verifiable, or are from studies using supplementation for short periods of time, less than a year. Most vitamin D studies are less than 6 months due to the high cost of such studies and do not reflect safety or toxicity over time. Clinical data strongly and definitively contradicts any belief that high doses of vitamin D, whatever the form, are safe. This issue is exhaustively addressed in the book. There have been a number of cases reported to me of severe vitamin D excess with serious and debilitating results, including significant bone loss. Wait for the book or order the Preliminary Report.

For the past number of years clinicians, physicians, national media, and the National Institute of Health have been warning Americans to stay out of the sun. The purpose of this warning is intended to prevent melanoma, a serious form of skin cancer. In spite of the ever-increasing use of sunscreens and intentional reduction of sun exposure, incidence of this cancer continues to rise. There is evidence that the advice to avoid sunlight may be contributing to the increased incidence of melanoma. One possible reason for this may be issues relating to genetics and extended exposure to UV-A light. When sunscreen is used sun burning is reduced or eliminated and the sunscreen user's time in the sun is extended. While UV-A is not as strong as UV-B it does cause damage over time and most sunscreens either do not block or poorly block UV-A no matter what the SPF may be. Whatever the cause, the expected reduction in skin cancer with sunscreen use has not occurred.  Also see: Melanoma Melodrama

One of the known protectors of skin cells from pre-cancerous changes is vitamin D and your skin actually contains the enzyme that converts sunlight D into active 1,25(OH)2D, calcitriol. For most Americans the primary source of vitamin D is sunlight. UV-B, the only band of light producing vitamin D, is significantly present only midday during summer months in most of the U.S., the exact time we are advised to avoid sunlight. UV-B is blocked by sunscreen. We have an international disaster in progress due to a misunderstanding of the nature of and need for UV-B and vitamin D.

A blood test for 25(OH)D, 25-hydroxyvitamin D, is the only way to tell if you have or are taking the correct amount of vitamin D, need to take any D or if your sun habits are sufficient. Too little vitamin D contributes to many degenerative diseases but excess vitamin D is equally undesirable. Because of the varied ethnicities, latitudes and lifestyles in the United States (and most of Europe too) the only way to safely use vitamin D is test, test and retest. Click on the Vitamin D Testing link for a relatively inexpensive way to monitor your D.

Low D needs to be corrected, carefully. Moderately high levels of 25(OH)D, greater than 70 ng/ml (175 nmol/l) have been associated with  bone loss, heart disease, and other soft tissue calcification. When chronic intake of excessive amounts of vitamin D raise serum 25(OH)D further irreversible damage may occur. It is likely for most the optimal range of vitamin D is 35-65 ng/ml (88-162 nmol/l). In locations greater than 30? latitude, north or south, values are naturally higher at the end of summer and early fall and lower in winter and spring. There is no evidence values higher than 60 ng/ml provide any added benefit.

TESTING: Reasonably priced testing is available for anyone in the US from the Life Extension Foundation. Click on the little sun to reach the test ordering page.  The test is $47 for LEF members and $63 for non-members. Test results are provided directly to you through the Foundation. Testing sites are easily accessible in most states.

Do not supplement in amounts greater than 800 IU (total from all sources) unless you are being tested and treated by a healthcare professional who understands clearly both the benefits and dangers of vitamin D. Minimum testing should not be less than every four months the first two years and every six months the third and fourth years. Excess intake of vitamin D may not show up in elevated 25(OH)D until as long as 2-3 years after starting a dose seemingly safe initially.

Sunlight is a safe source for most persons in the US with the exception of light skinned persons living in Hawaii, Florida or other locations with elevated levels of UV-B. If you have light skin and live in an area with high UV-B, sunning should be very limited. Combining sunlight and supplements can rapidly overload the D endocrine system in summer months. If you regularly sun in summer and have skin types 1-4 it is unlikely any supplementation is needed during all or most of the year. For dark skins the only US location likely to provide adequate sunlight is Hawaii (this is yet to be determined) and supplements may be a requirement for long term health. As response to supplementation is difficult to gauge testing should be mandatory. The Preliminary Report below and the book explain how to determine your need and how to use supplements and sunlight safely.

 Vitamin D, the kind you make on your skin, get in fortified milk, or take in a vitamin supplement, is not a vitamin. It is more appropriately classified as a pro-hormone. Not only is it a pro-hormone it is a sunlight derived pro-hormone. The active hormone D, calcitriol, controls calcium in vertebrates and invertebrates. Calcium controls innumerable processes in the human body including responses in muscles, bones and glands. Calcitriol is a major player in genomic actions determining how our cells express themselves and regulating production of numerous substances including enzymes, hormones and neurotransmitters

 We all need sunlight and/or vitamin D. Clinical studies demonstrate the need for sunlight and vitamin D is genetically variable. At the present time many persons world-wide suffer from D deficiency or insufficiency. Testing is the only way to know how much D you have and testing is the only way to monitor D supplementation. As actions of a pro-hormone are essential to health and life,  'guessing' or 'assuming' is not a wise way to determine optimal levels.

In northern California 80% of clients tested during winter months have serum vitamin D deficiency or insufficiency. This problem increases dramatically in persons living at latitudes more distant from the equator and in persons living in all US latitudes with darker skins. In Texas there has been an increase in the number of children with black and Hispanic parents suffering from rickets. Even in sunny southern California vitamin D deficiency or insufficiency is prevalent in part due to avoidance of midday sunlight and the use of sunscreens which block vitamin D production .

Getting enough vitamin D, from sunlight or supplements, is important to health and longevity but too much supplemental D or sunlight can be disease producing. Too much, too little- the only way to know how much D you have and how much sunlight or D you need to maintain D sufficiency is to test.

 Every body needs sunlight and vitamin D. Deficiency or insufficiency has been associated with: