A CANCER DIETARY-APPROACHES PROBLEM
There is a problem with some dietary approaches like Gerson therapy. Whilst in some ways the diet (at least, without the coffee enemas) could be regarded as healthy, it may be unsuited to some types of cancer patients. For example, patients with pancreatic cancer tend to lose weight rapidly. Following a diet that will tend to bring about weight loss in healthy individuals is thus actively harmful when weight loss is part of the problem being faced. Also, as already noted, many patients tend to ‘mix and match’ the conventional with the alternative. Treatments such as chemotherapy can lead to digestive problems and promote weight loss. It is thus easy to see that a very high-fibre diet, relatively low in calories, may not be ideal in such circumstances. The alternative practitioner would, of course, argue that the problem here is the conventional not the alternative part of the treatment. This would be an acceptable line to run if these treatments were subject to proper scrutiny with proven efficacy. For Gerson therapy, despite 90 years of use, many published case reports, and reviews by academics, there is still not a single published clinical trial. Rather as with drugs, I feel it is for the proponents of such treatments to arrange trials, just as the drug companies have to demonstrate effectiveness to obtain a licence for their products. There may well be patients who do benefit from ‘alternative’ dietary approaches, but at present, the evidence is lacking.
Closely linked to alterations in a diet are nutritional supplements based on either vitamins and minerals or herbal mixtures (sometimes called ‘nutriceuticals’). These therapies are potentially more amenable to conventional clinical evaluation than the complete lifestyle change advocated by groups such as the Gerson therapists. The simplest version of dietary supplementation is with either vitamins or minerals. Vitamins (a derivative of the compound words ‘vital amines’) are chemicals present in tiny amounts in foodstuffs and are essential for the body to maintain normal functions. A good example is vitamin C, derived from various fruits, particularly citrus ones. Shortage of vitamin C leads to that scourge of ancient mariners, scurvy, a condition in which wound healing is impaired, tissues become fragile and bruise and bleed easily, gums bleed, and teeth fall out – the body’s so-called ‘connective tissue’ fails to connect things properly. Clearly, therefore, vitamin C is essential for life, but if we have sufficient, is there any benefit in taking more? The Nobel prizewinner Linus Pauling became convinced that there was the benefit in so-called ‘mega-doses’ of the vitamin, and he vigorously advocated the practice for various ailments from the common cold to cancer (it should be noted that he got the Nobel for physics, not medicine). Now here we have a readily testable hypothesis – vitamin C can be put in tablets and assessed like any other medicine. This was duly done in various settings and the answer was a resoundingly negative one – dietary supplementation of vitamin C above normal levels did not help fight cancer (or anything else). Nonetheless, hard evidence of lack of efficacy in no way prevents the alternative practitioners from continuing to promote the use of the agent, as the most cursory of online searches will confirm.
Even doing trials with simpler substances – minerals – turns out to be very difficult. For example, selenium is present in vegetables and is an essential component of tissues, being involved in the maintenance of the integrity of epithelial membranes – the lining cells of the body’s various tubes and glands. It is these cells that give rise to the common cancers, and thus a lack of selenium would seem a potential candidate for a dietary top-up. Further studies demonstrated that populations with lower selenium levels had a higher risk of cancer. This prompted trials of selenium supplementation in patients with cancer, and one famous study in skin cancer showed that the patients receiving the extra selenium had a lower risk of getting second cancer – of the prostate. The problem was, this was not what the trial was studying, but nonetheless, it was sufficient to trigger the mass consumption of selenium by men concerned about their prostates. To confirm the effect, a huge trial called SELECT was set up in the USA looking at two supplements – selenium and vitamin E. After recruiting 30,000 men, who were allocated, either one or other supplement, both, or neither in a blinded fashion, the trial was stopped by the Data and Safety Monitoring Committee. By this point, the men had been followed for an average of 5 years. The Committee found that not only was there no suggestion of any benefit from either agent but, more troublingly, there was the possibility that there was a slight increase in the risk of prostate cancer with selenium and, unexpectedly, the possibility of an increased risk of diabetes with vitamin E.