Summer 2013/14 True Natural Health Magazine – Your Questions Answered
By Roger French



  1. The best way to get vitamin D is from sun exposure, but some vitamin D is formed on the surface of the skin and soap washes this off, so we lose some of the sun-produced vitamin. This view is presented in your book, How a Man Lived in Three Centuries, and also in the article in the Summer 2009/10 issue of Natural Health and Vegetarian Life, page 16. If this is true, we either have to shower every third day or not use soap.
  2. Does shampoo have the same effect as soap?
  3. Why do we need a daily dose of vitamin D, considering it is fat soluble and can be stored in the body?
  4. Is it possible to tan the skin too much, so that the sun’s rays can’t penetrate it?
  5. Irregular sunbathing is said to contribute to melanoma. If I sunbathe every third day, it this too irregular?
  6. Skin cancer may be contributed to by omega-6 oils. Would the same apply to omega-9 and saturated fat?
  7. Can a person get enough vitamin D sunbathing during winter?
  8. If eating vegan, the diet is cholesterol free. Would the liver be able to produce enough to enable adequate vitamin D synthesis?
  9. Elderly people have less ability to synthesise vitamin D. Should they also take supplements?



1. Soap washes away vitamin D

This subject has been studied by John Cannell, MD, of The Vitamin D Council, a not-for-profit organisation, educating the public on vitamin D and sun exposure. His account, given on 31st January 2012, is as follows

Professor N. Binkley and his colleagues found that surfers and skate-boarders in Hawaii had lower blood levels of vitamin D than very dark-skinned hunter-gatherers in Africa. They wondered, why would light-skinned, sun-drenched outdoor sport enthusiasts, having 11 hours of full-body sun exposure per week with no sunscreen, have lower levels than the Africans who probably wouldn’t be out in the sun in the middle of the day anyway? Latitude could explain some of the difference, but there is another likely explanation. (Binkley N, et al. ‘Low vitamin D status despite abundant sun exposure’. J Clin Endocrinol Metab. 2007 Jun;92(6):2130-5.)

Researchers way back in 1937 had concluded that washing the skin by the usual methods removes vitamin D and its precursors from the outer layer of the skin (Helmer AC, Jensen CH: ‘Vitamin D precursors removed from the skin by washing’. Studies Inst Divi Thomae 1937, 1:207-216).

What they showed is this. Some of the vitamin D we make is on the surface of the skin, and water can wash it off. How much humans make on the surface and how much inside the skin, no one knows. However, the vitamin D levels of the African tribesmen are consistent with the proposition that humans living in a natural state make a significant proportion of vitamin D on the surface of their skin for later absorption. Assuming the African hunter-gatherers did not take showers daily the way so many cosmetically brainwashed Americans and Australians do, then we can conclude that plain water, but especially with soap, routinely washes off the skin oils containing vitamin D, a fat-soluble steroid hormone.

Numerous authorities agree with the views of Dr John Cannell. One of them is the highly respected Dr Mercola who holds the view that soap does wash the vitamin D off the skin.  

Another group is the Skeptics Stack Exchange, a question and answer site for scientific scepticism (website The view of this group is as follows.

When the skin is exposed to UVB radiation from the sun, a cholesterol derivative in and on the skin is converted into vitamin D3. However, the vitamin D3 formed on the surface of the skin is not absorbed immediately, but takes up to two days to be fully absorbed.

Therefore, a shower with soap will wash away much of the vitamin D3 that was generated on the surface of the skin. So to retain most or all of the sun-generated vitamin D, we need to delay washing with soap for about two full days after sun exposure. But few people are going to go without bathing for two full days. The compromise is to use soap in armpits and groin area, but avoid soaping up the larger areas of the body that were exposed to the sun.

Also, people who have very dry skin with little oil may make less vitamin D than people with oily skin.

 Although the washing-and-soap theory has not actually been proven, and we don’t yet know how much vitamin D is produced on the surface of the skin or inside it, this vitamin is so important for disease prevention that it might be a very good idea to assume that the theory is trueThis issue raises the question – why use soap at all, unless there is grease or dirt on the skin? About 40 years ago, a Texas dermatologist, Prof. Knox, warned that soap is a harsh, alkaline, irritating chemical that washes the natural oil off the skin and leaves it prone to becoming dry, cracked and scaly. Water alone is usually enough to get us clean and remove the source of body odour. If there is dirt or grease on the skin, such as after gardening, painting or working on the car, then soap is, of course, necessary, although only on the hands and other unclean parts.


2. Shampoo

This is designed to remove oil the same way as does soap, so it will have a similar effect.


3. Why do we need a daily dose of vitamin D?

We don’t. The body does store it, the best evidence being that the vitamin produced in summer can complement our supply in winter. The fact that it is stored in body fat is why excess can be toxic. 


4. Can we tan too much?

If an extreme tan could prevent the sun’s rays penetrating the skin and preventing vitamin D production, then all tropical native people with dark skins would be deficient in D. If anything, the opposite is the case. Multiple sclerosis is prevented by vitamin D, and its incidence is lowest at the Equator – indicating plenty of D in tropical peoples – and highest towards the Poles.


5. What frequency of sunbathing is irregular?

I can only assume that sunbathing every third day rates as regular. Irregular sunbathing is when we have so little tan that when we sunbathe, we burn easily. Sunburn is the danger for melanoma and other skin cancers.


6. Omega-6 oils and skin cancer

The problem with omega-6 oils is that, being highly unsaturated, they are very prone to oxidation, and oxidised fat is very carcinogenic and artery damaging. This does not apply to omega-9 or the saturated fat in plants. Coconut fat is highly saturated, but is very safe and healthy to consume or to apply topically.


7. Vitamin D during winter

Can a person get enough vitamin D sunbathing during winter? In Qld yes, but  in Tassie probably not. The solution is to take a supplement of vitamin D3 but only after blood tests to ensure that a top-up is necessary. After taking the supplement for a number of months, blood tests are virtually essential to check that levels have not gone too high into the toxic range.


8.  Vegan diet supplies no cholesterol

This doesn’t matter a scrap because the liver normally makes all the cholesterol we need. In animal protein diets supplying cholesterol, the liver simply learns to make less. So on a vegan diet, vitamin D synthesis should be unaffected.


9. Elderly people and vitamin D.

Elderly people have less ability to synthesise vitamin D, so should they take supplements? The only sure answer is to do as above under ‘Vitamin D during winter’ – have blood tests and take supplements if the need is indicated.