Take, as an example, the groundbreaking work of Dr Frank Apperly, from the University of Melbourne, who discovered in 1941 that sunlight could have a protective effect against many cancers, including breast, lung, prostate and colon. By studying cancer statistics for North America, he noted that people who live nearer to the equator have far lower incidence of cancer.
Over the 65 years since, many studies have confirmed and added detail to Dr Apperly's initial observation. Not surprising as sunlight is the richest source of vitamin D, which is an essential anti-carcinogenic.
Two studies, published last week, confirm the vital role that the vitamin plays in preventing breast cancer. In the first, carried out by Imperial College London, women who had higher intake of vitamin D - from sunlight, cod liver oil or milk - between the ages of 10 and 29 had a 40 per cent reduced risk of developing breast cancer later in life. They think that the protective effect may happen during puberty when the breasts are developing.
In the second study, from the University of California, women with high levels of vitamin D in their blood halved their risk of developing breast cancer.
However, the greatest protective effect occurred when levels were 52 nanograms per millilitre of vitamin D, which equates to a daily intake of 1,000 IU, a level that is hard to reach by dietary means alone. The best food sources of vitamin D include eggs, liver, fish, liver oils, and oily fish such as salmon, sardines, trout and tuna - but sunlight is by far the best.
Meanwhile, our health guardians continue to hammer on about the harmful effects of sunlight, a topic that Dr Apperly also addressed. He discovered that it was not sunlight per se that caused skin cancers, it was the temperature associated with it that did the damage. High exposure to sunlight in cooler climates with mean temperatures below 5.5 degrees C (42 degrees F) didn't raise the incidence of skin cancer.
And as we've outlined in previous E-news bulletins, you know you're getting a beneficial exposure to sunlight if it slightly reddens the skin.
(Sources: Journal of Clinical Pathology, 2006; 17 October. Published online at: www.jcp.bmjjournals.com (Imperial College study). Nutra-Ingredients, USA, published online on 17 October 2006 at: www.nutraingredients-usa.com (University of California study)).
E-news broadcast 26 October 2006 No.304 [Subscribe]