McCarrison's heroic studies, whatever may be thought of the suffering of the animals involved, have provided a basis for understanding a relationship between nutrition and health and can help us to see the relevance of Weindruch and Walford's research more clearly. There is a direct correlation between diet and disease, and the restricted patterns of eating which this research has looked into (in contrast to what might commonly be eaten in industrialized societies) are seen to have clear benefits to offer in terms of reduced levels of disease. But, what effect on everyday ability to function does a restricted diet have in humans?

Do Kuratsune's dietary experiment on himself and his wife
Interesting results emerged when Professor Masanore Kuratsune, former Head of the Medical Department of the University of Kyushu in Japan, decided to see what would happen if he followed a restricted dietary intake similar to that provided to concentration camp inmates, using the same food content, sometimes cooked and sometimes raw.

He and his young breast-feeding wife continued with their activities and normal lives during the length of the three periods of restricted feeding involved (120 days, 32 days and 81 days). The quantities of food consumed daily were between 22 and 30 grams of protein, 7.5 to 8.5 grams of fat, and 164 to 207 grams of carbohydrate. This amounted in total to between 729 and 826 calories daily (whereas the recommended minimum would be 2,150 calories for their body size).

In camp conditions there was often a rapid onset of ill-health, with infection and anemia common, while nothing of the sort occurred during these three periods of restricted diet, apart from when the intake of food was switched from raw to cooked food. The diet of fresh and raw food (consisting entirely of whole grain rice (soaked not cooked) plus shredded greens and fruit, with no animal protein at all) kept the couple healthy and active, with the wife finding her milk supply increased rather than decreased. But, when the experiment switched to cooked food (same ingredients) they both developed symptoms of hunger, oedema and weakness, which vanished when the eating of raw food was reintroduced.

This personal study was recounted in a 1967 monograph written by Dr Ralph Bircher of Zurich, and entitled Way to Positive Health and Vitality published by Bircher-Benner Verlag, Switzerland.

Raw food diet applied to rheumatoid arthritis at London Hospital
Dr Ralph Bircher also outlines the application of a raw diet, restricted in calories, to people with chronic disease, citing the dozen classic cases documented on film, in which the dietary approach developed by his father Dr Max Bircher-Benner was used at the Royal Free Hospital in London just before the Second World War.

One of these cases is outstanding in its demonstration of just what can happen when dietary restriction is applied to a serious crippling degenerative disease like rheumatoid arthritis. This involved a 55-year-old woman who had been afflicted with this condition for over two years and who was bed-ridden, unable even to sit up, and quite unable to stand, walk or use her arms or hands. She was dependent upon two people for all her needs.

For two weeks she consumed nothing but raw food, salads and fruit, following which she was allowed a liffle lightly cooked vegetable food as well as the raw food. For six weeks there was no change apart from the development of even more severe pains, and finally a high temperature. This was seen as the turning point, following which improvement was seen month by month until after five months she was walking with sticks. By ten months she was pain-free and had regained most of her mobility. One year after beginning the programmed she was fully mobile. Ten years later, still following a 75 per cent raw food diet she was digging her garden and growing her own food.