Positive Health Online

This is an authoritative and exceedingly politically incorrect book, with hundreds of references to the scientific literature. Dr Hobday, in addition to challenging many mainstream holy grails regarding the pivotal role of the sun to our health, has presented a quite refreshing juxtaposition of many diverse topics – epidemiology of cancer, heart disease, and multiple sclerosis, treatment of tuberculosis and wounds by helio(sun)therapy, Chinese martial arts, and architecture.

Against the well-accepted mantra that sun and sun tanning is harmful and causes skin cancer, and that exposure to the sun must be avoided at all costs, Dr Hobday begins with the quite remarkable statement that there is a considerable body of scientific evidence demonstrating that 'sunlight may play a key role in preventing and ameliorating a number of serious degenerative and infection diseases, including cancers of the breast, colon, ovaries and prostate; diabetes; high blood pressure; heart disease; multiple sclerosis; osteoporosis; psoriasis; rickets and tuberculosis.'

He describes the components of sunlight – visible light, ultraviolet radiation and infra-red radiation, and the two wavelengths which affect the skin – ultraviolet A (UVA – 320-400 nm) and ultraviolet B (UVB – 290-320 nm). Whereas until recently, UVA was considered to be relatively safe, it has now been shown that UVA rays penetrate deeply into the skin. Repeated exposure to the sun over many years leads to premature ageing, atrophy of the skin and even skin cancer. However, exposure to the sun is beneficial to certain skin disorders, including psoriasis, certain types of acne, some bacterial and fungal infections and the rare malignant skin cancer mycosis fungoides.

The author explores the complex biochemical cascade arising from sunlight, including interactions affecting the synthesis of vitamin D, hormones including melatonin, the pigment melanin, the minerals calcium and magnesium, blood pressure and cholesterol levels, even evidence that exposure to sunlight protects individuals from internal organ cancers, osteoporosis, multiple sclerosis and jaundice.

In these days of acceptance of the role of antioxidants to prevent diseases including cancer, I found impressive the less publicized epidemiological evidence showing strong relationships between distance from the sun and death rates of colon and breast cancers. In those countries farther away from the equator, the higher the death rate; in those closer to the sun, the lower the rate. In European countries such as the UK, Netherlands, Germany and Austria, colon death rates, per 100,000 people, published in 1999, are about 16; in Spain, Greece, Chile, Florida, Mexico and Hawaii, they are between 5.5 and 8.5. Similarly breast cancer rates in European countries are about 26-29; in more southern countries they are about 12-15. Similar evidence also exists for prostate and ovarian cancers, heart disease, diabetes (sunlight has a similar effect to insulin in that it lowers blood concentrations of glucose) and multiple sclerosis. Not only are the precise mechanisms behind the sun's protection of these conditions not known; there appears to be a lack of research into even, for instance, vitamin D levels across the UK population.

Some of the most interesting aspects of this book relate to the historical use of sunlight therapy proving not only that sunlight can kill bacteria, but also describing the clinical application of heliotherapy to cure tuberculosis and war wounds by British and European scientists and physicians of the 19th and 20th centuries. The photos of the afflicted children which were cured of tuberculosis are astonishing! Not sunbathing in any sense of the word, these doctors employed a totally systematic regime of exposing, very gradually (5 minutes per day to start) very restricted regions of the bodies to the sun, usually early in the morning in cool temperatures, until a tan was established. There was also an emphasis upon a wholefood diet of fresh fruits and vegetables, grains and pulses.

Discussed in the book are depression, SAD, hydrogenated and trans-fatty acids, possible links between fluorescent lighting and malignant melanoma, and the possible role of vitamin D in the inhibition of malignant melanoma and other cancers. Dr Hobday is exceedingly responsible in not advocating that people go out in the midday sun in hot weather; he advocates that we eat a high quality diet, engage in moderate outdoors exercise in cool temperatures (such as Tai chi at sunrise) and live and work in buildings that let in adequate and healthful amounts of natural sunlight. Here is an important book whose messages we ignore at our peril.