May 2005

Vol. 4, No. 5

<<< Return to Newsletter Home Page

Printer Friendly Page

Subscribe to this newsletter at

Sunny Days, Keeping Those Clouds Away�

Have you ever wondered how something as natural and omnipresent as sunlight could hurt you?  Over eons of evolution (or by Divine creation, if you choose) people have been exposed to the sun�s radiation � you would think by now we would have adapted so as to live in harmony with this enveloping environment.  Yet, expert doctors warn us to avoid almost any exposure to these potentially damaging rays � the sun�s radiation is known to suppress our immune system, give us cancer, and cause us premature aging. 

However, there is a dilemma: we need this form of radiant energy for good health � in fact, without it our bodies become diseased with severe bone deformities (rickets).  Most recently, research has shown that without the sun�s life-giving energy we are at thirty times greater risk of death from cancer. 

Everyone feels better when the sun comes out.  In addition to the cosmetic effects of tanning � making people more satisfied with their appearance � sunlight causes people to feel more active, energetic, balanced, strengthened, and less nervous.1  Many people can identify with the low-sunlight, winter depression symptoms of fatigue, lowered motivation, sleepiness, increased appetite, weight gain, irritability, and decreased sociability.2  Nicely summarized, sunshine is health and happiness.


Sunshine Is a Potent, But Non-profitable Remedy

For centuries, doctors and natural healers relied on medical treatment by sunlight, called Heliotherapy, to help heal many common ailments.  Scientific research shows sunshine to be an effective treatment for rickets, osteomalacia, osteoporosis, acne, eczema, psoriasis, neonatal jaundice, and depression (Seasonal Affective Disorder).7-8  Most recently, solar energy has been found to prolong the life of people with our most common forms of cancer.6-7  All considered, when was the last time you heard of a doctor recommending an hour of afternoon sunning for a patient�s troubles?  And which pharmaceutical company sells sunshine?



Health and Healing from the Sun�s Energy3-7

A few known benefits of sunshine:

Lowers cholesterol
Lowers blood pressure
Promotes thyroid stimulation
Regulates the immune system
Stimulates insulin production
Improves heart muscle contractility



Currently prescribed for the treatment of:

Neonatal jaundice



Has a role in the prevention of:

Heart Disease
Type-1 diabetes
Multiple Sclerosis
Rheumatoid Arthritis
Crohn�s disease
Cancers of the:



Multiple myeloma
Non-Hodgkin�s lymphoma


Explanations for the benefits of the sun�s energy have focused almost exclusively on vitamin D.  The truth is the therapeutic effects from the sunlight are much broader than the simple synthesis of this important substance.  For example, the connection between sunlight and our well being is through the increased production of the feel-good brain chemical, serotonin.8   Motion of the sun, perceived through our eyes, from sunrise to sunset, sets our biological clock and determines our circadian rhythms.  Much is yet to be unraveled about the mysteries and miracles of sunshine.  However, for this moment let�s focus on vitamin D.

The �Vitamin D� Connection

The main function of vitamin D is to maintain the body�s calcium concentrations at a precise level.  This is accomplished by increasing the absorption of calcium from the intestines and the interaction with other hormones (like parathyroid hormone).   Almost all tissues and cells in the body have receptors for this hormone, and therefore are affected by its presence.

More than 90% of the vitamin D requirement of people is met by internal synthesis with the aid of sunlight, not from the diet.4 Very few foods naturally contain vitamin D.  Examples are: fatty marine fish (salmon, cod liver oil, mackerel, and  sardines); and a few foods are fortified with vitamin D, like cow�s milk sold in the United States, as well as some orange juices, cereals, and breads � the vitamin is added during manufacturing.  Vitamin supplements (pills) are also common sources of this active substance. 

In children, vitamin D deficiency will cause a disease characterized by the severe bone deformity called rickets.  In adults, osteomalacia (a weakening of the bones) may develop � along with muscle weakness, and aching bones and muscles.  A role for vitamin D in cancer prevention has recently become a topic of much discussion.  Since 1941 researchers have reported that common cancers, like breast, prostate, and colon, are less common where people get more intense sunlight, nearer the equator.7

Consumption of cow�s milk is believed to increase the risk of aggressive and advanced cancer, especially prostate cancer, by interfering with vitamin D activity.7  More specifically, the much-raved-about calcium in milk suppresses circulating levels of this hormone, encouraging cancer growth.  Anticancer effects of vitamin D are: regulation of cell growth, helping older cells die when they are supposed to (apoptosis), inhibiting the formation of new blood vessels that feed cancers, stopping the spread of cancer (metastasis), and helping to prevent out-of-control cellular proliferation � a hallmark of cancer.   The benefits are not just limited to prevention � there is good evidence that sunlight exposure can benefit those who have already been diagnosed with cancer.7

�Vitamin D� Is Not Really a Vitamin

 �Vitamin D� is a misnomer.  Vitamins, by definition, are not synthesized by our body, but are small organic substances which must be acquired through our foods.  Because we easily synthesize this biologically active substance, it is by definition a hormone � created by the action of sunlight on plant-derived sterols circulating through the exposed layers of our skin.  Thus, it is commonly referred to as the �sunshine vitamin,� but more correctly it should be called the �sunshine hormone.�   This hormone only becomes a �vitamin� under the unnatural living conditions of severe sunlight deprivation.  In this case, the only available source may be diet.  

The amount of this hormone needed by our bodies is very small.  The exposure of skin sufficient to cause a slight pinkness produces vitamin D levels equivalent to 20,000 IU (as supplied by pills).  This is 100 times greater than the RDA for adults under 50 years old, and 20 times greater than the highest recommendations for daily oral supplements.3   Vitamin D toxicity is never caused by excess sunlight exposure.  Sunscreen with an SPF of 15 or greater can reduce vitamin D production by 95%.4

Because vitamin D is fat soluble, it is effectively stored in the body�s own fatty tissues where it serves as a �sunshine battery� �for later use during the darker days of winter.  With obese people, this hormone is �sucked� so successfully into the body fat that much of it becomes essentially unavailable for future use � this is proposed as one reason obese people have more risk of cancer.  

Unquestionable Harms from Overexposure 

Sunlight is a form of powerful radiation, so it should not surprise you that there is a potential for harm.  This ultraviolet light suppresses our cancer fighting immune system and causes the formation of free radicals which damage our cells, including their genetic materials (DNA). Repeated, severe injuries to the skin�s elastic structures cause it to wrinkle, an unsightly sign of aging.  Years of overexposure can lead to precancerous, actinic keratosis, and then actual cancers � basal cell and squamous cell carcinomas.  Ultraviolet light is one of only 60 agents designated by the World Health Organization as a human carcinogen.6  More than 1 million cases of skin cancer annually are attributed to sun exposure. 6  This represents 55% of all cancers in the USA. Fortunately, these forms of skin cancer are rarely fatal. 

This dark side counters our love of the sun and all the scientific evidence that substantiates its benefits � so what went wrong?

Unnatural Living Causes the Sunshine Paradox

Three changes in our natural condition now place us in harm�s way:

The First Man-made Change: Migration

I (John McDougall) am of Scotch-Irish decent and my skin is fair with a very low level of pigmentation (melanin) which allows the sun�s vital radiation to easily penetrate its outer layers. Because of this efficiency, I can make all the vitamin D I need from as little as five minutes of exposure to my face, hands and arms (6% to 10% of my body) at noon, two to three times a week, while living at a latitude similar to Detroit�s. 

My sun exposure changed drastically in my mid-twenties when I migrated from Michigan (42 N latitude) to Hawaii (21 N latitude).  As a result, I became a �white boy� living in an environment fitted for much darker-skinned people.  I sunned my body on the beach, sailed on my boat, windsurfed, and hiked without a hat for 15 years, often at high noon in the summer months.  The result was sun damage to my skin that I live with to this day.  I also ate a high-fat, low-plant food diet during my early years in Hawaii.

Darker-skinned people � Africans, Middle-Easterners, and some Asians, for example � can develop just the opposite problem by migration.  Living for eons in lands of intense sunshine, their skins became heavily pigmented (lots of melanin) to block out the sun�s powerful radiation.  Over the last 400 years, millions of these people have relocated to lands of limited sunshine, like cloudy London or to an office building in New York City.  Dark skin requires as much as 10 to 50 times the solar energy to make the same amount of vitamin D as does fair skin.7  The consequence is too often vitamin D deficiency, which may be one reason that blacks living in the USA have so much more internal cancer than whites have.  Deficiency in their children also causes rickets.   It is estimated that over 50% of African-Americans in the USA are at risk of vitamin D deficiency, compared to only 5% of whites.4,7

The Second Man-made Change: Nutrition

Animal experiments reported as early as 1939 provided the first clues about the influence of our diet on the risk of skin damage from sunlight.9  Researchers discovered a diet high in fat increased the numbers of ultraviolet (UV) radiation-induced skin cancers in mice. In the 1980s, studies showed that switching from a high-fat to a low-fat diet immediately after the ultraviolet light exposure reversed the cancer-promoting effects of the high-fat diet.9 These findings suggested that changing a person�s diet, even after exposure to UV light, might prevent future skin cancers, and possibly reverse the effects of the sun�s damage.

This may surprise you, but even more than animal (saturated) fat, polyunsaturated oils derived from vegetables (like corn and safflower oils) are found to be the strongest promoters of skin cancers in people and experimental animals, of any foodstuffs that we eat.10  This danger only applies to free oils, like those found in a bottle.  Please understand that when the oil is still in its natural state, as part of the components of the fruit or vegetable, it is perfectly safe, and as you know, health-promoting.

The most serious warning about the sun comes from the fear of developing the very deadly skin cancer, melanoma.  This fear is unfounded.  Research clearly shows that sun exposure has little to do with the cause of this kind of cancer � in fact, there is good evidence that sunshine can help prevent this vicious cancer, and can even slow its growth � doubling a patient�s chances of surviving.11,12  Melanoma is believed to be due to a diet high in fat, especially vegetable oils, and low in fruit and vegetables.13

Even if you have skin damage, it is not too late to change your eating habits.  An experiment published in 1994 in the New England Journal of Medicine reported that people with actinic keratosis (precancerous, dry, scaly, rough-textured patches) were able to reduce the chances of development of new actinic (sun damage) lesions, 3 to 6-fold, by switching from a high fat (38% of calories) to a relatively low-fat (21% of calories) diet � this diet was also more plentiful in plant foods.14  Furthermore, during the last 8 months of the study the incidence of skin cancers was 10 times less in the low-fat group than the high fat dieters.15  (The McDougall Diet is 7% to 10% fat and made of only plant foods.)  

The Third Man-made Change: Atmosphere

The intensity of the sun�s radiation delivered to our skin is increasing because of industrial damage to our atmosphere.  Of the types of radiation emitted by the sun, ultraviolet radiation is believed to be almost entirely responsible for the deleterious effects sunlight can have on our systems.  The amount of ultraviolet radiation that actually reaches the earth�s surface depends on latitude, altitude, and weather conditions, and on the amount of ozone, water vapor, oxygen and carbon dioxide in the atmosphere. However, the ozone layer is becoming chemically depleted because of the presence of chlorofluorocarbons (CFCs) in the stratosphere. CFCs are used in air conditioners, and as cleaning and spraying agents in the chemical industry. In 1985, it was reported that there is a hole in the ozone layer over Antarctica and there is additional evidence that ozone is being lost at nearly all latitudes outside of the tropics. 

Action for You to Take 

My observations of the world affirm for me that Nature makes few (if any) mistakes and all forms of life are supported by natural surroundings, which exist in delicate balances.  Unfortunately, the equilibrium has been upset and in some ways sunshine has been turned from a friend to a potential foe.  Your first response must be to take every step to put things back into balance by making adjustments to receive the proper amount of sun you need based on your skin pigmentation.  This may mean at one extreme hours of exposure for dark-skinned people living in low-light conditions, and at the other extreme great efforts to minimize exposure in fair skinned people living near the equator.

Because of the recent worsening atmospheric conditions, especially if you are fair skinned, you may need to wear protective clothing, avoid sun exposure during peak hours of radiation, and use sunscreens.  Use of protective agents is a must for areas of skin that have already been damaged � commonly, your face, neck, shoulders, and hands.  However, you can still choose to increase sun exposure to undamaged areas of skin such as your legs, abdomen and back in order to obtain the health benefits of this radiant energy.  The safest way to benefit from the healing powers of sunlight may be to build your exposure slowly throughout the year and to avoid burning from impulsive intense exposures.

Regardless of skin tone, occupation, present geographic location, or current health, a change to a low-fat, plant-based diet (the McDougall Diet) is always recommended for better skin � the benefits are almost limitless and there are no added costs or adverse effects from this simple step.  This kind of eating is so powerful that it actually provides some of the same biochemical benefits as sunlight without any of the risks.5

I do not recommend vitamin D supplements, except in those extremely rare cases (such as confinement to a nursing home or exile to the Arctic) where you cannot get the most reliable and beneficial source of vitamin D � sunshine.

The components of life that provide radiant health for you are:  clean air, water, and food, adequate rest, moderate exercise and sunshine.   These are cost-free and side-effect-free.  But also profit-free, so don�t expect much outside encouragement for their liberal use. 

Effective, Scar-free Treatment for Sun-Damaged Skin

If you develop actinic keratosis, basal cell or squamous cell carcinomas, there is a simple, highly effective, low-cost treatment.  The cosmetic results are excellent; rarely leaving scars, such as would be expected following surgery.

Aldara (imiquimod) 5% cream is by prescription only, but it is self-administered.  Results are exceptionally effective � even the cancers disappear.  Cream is applied every day or every other day until an eruption occurs (like poison oak).  The eruption heals, leaving normal skin in most cases.  Only sun-damaged cells are affected by this treatment.  See prescribing information for details.


1)  Gambichler T, Bader A, Vojvodic M, Bechara FG, Sauermann K, Altmeyer P, Hoffmann K.  Impact of UVA exposure on psychological parameters and circulating serotonin and melatonin.
BMC Dermatol
. 2002 Apr 12;2(1):6.

2)  Magnusson A.  Seasonal affective disorder: an overview.  Chronobiol Int. 2003 Mar;20(2):189-207.

3) Holick MF.  Vitamin D: importance in the prevention of cancers, type 1 diabetes, heart disease, and osteoporosis. Am J Clin Nutr. 2004 Mar;79(3):362-71.

4) Holick MF.  Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers, and cardiovascular disease.  Am J Clin Nutr. 2004 Dec;80(6 Suppl):1678S-88S.

5)  McCarty MF.  A moderately low phosphate intake may provide health benefits analogous to those conferred by UV light - a further advantage of vegan diets. Med Hypotheses. 2003 Nov-Dec;61(5-6):543-60.

6)  Egan KM, Sosman JA, Blot WJ.  Sunlight and reduced risk of cancer: is the real story vitamin D? J Natl Cancer Inst. 2005 Feb 2;97(3):161-3.

7)  Giovannucci E.  The epidemiology of vitamin D and cancer incidence and mortality: A review (United States).  Cancer Causes Control. 2005 Mar;16(2):83-95.

8)  Hoekstra R.  Effect of light therapy on biopterin, neopterin and tryptophan in patients with seasonal affective disorder.  Psychiatry Res. 2003 Aug 30;120(1):37-42.

9)  Black HS.  Influence of dietary factors on actinically-induced skin cancer.  Mutat Res. 1998 Nov 9;422(1):185-90.

10)  Harris RB, Foote JA, Hakim IA, Bronson DL, Alberts DS.  Fatty acid composition of red blood cell membranes and risk of squamous cell carcinoma of the skin. Cancer Epidemiol Biomarkers Prev. 2005 Apr;14(4):906-12.

11)  Berwick M, Armstrong BK, Ben-Porat L, Fine J, Kricker A, Eberle C, Barnhill R. Sun exposure and mortality from melanoma. J Natl Cancer Inst. 2005 Feb 2;97(3):195-9.

12)  Christophers AJ.  Melanoma is not caused by sunlight.  Mutat Res. 1998 Nov 9;422(1):113-7.

13)  Millen AE, Tucker MA, Hartge P, Halpern A, Elder DE, Guerry D 4th, Holly EA, Sagebiel RW, Potischman N. Diet and melanoma in a case-control study.  Cancer Epidemiol Biomarkers Prev. 2004 Jun;13(6):1042-51.

14)  Black HS, Herd JA, Goldberg LH, Wolf JE Jr, Thornby JI, Rosen T, Bruce S, Tschen JA, Foreyt JP, Scott LW, et al.  Effect of a low-fat diet on the incidence of actinic keratosis.  N Engl J Med. 1994 May 5;330(18):1272-5.

15)  Black HS.  Influence of dietary factors on actinically-induced skin cancer. Mutat Res. 1998 Nov 9;422(1):185-90.

16)  Burns CA, Brown MD. Imiquimod for the treatment of skin cancer.
Dermatol Clin. 2005 Jan;23(1):151-64, vii.

<<< Return to Newsletter Home Page

Email this page to a friend or coworker

  You may subscribe to this free McDougall Newsletter at
  Newsletter archive

2005 John McDougall All Rights Reserved