A range of data on the benefits produced by simple health interventions in late life suggests that many people are self-sabotaging to a point at which a significant fraction of age-related disease and mortality might be legitimately thought of as being self-inflicted. To pick one example, if programs of moderate exercise improve health and reduce mortality in old people, which they do, then the conclusion must be that older people are harming themselves by not undertaking sufficient exercise.
Cancer is one of the more important classes of age-related condition. It is age-related for a range of reasons, such as rising levels of chronic inflammation that make the tissue environment more hospitable to cancerous growth, and the progressive failure of the immune system to identify and destroy pre-cancerous and cancerous cells at the earliest stages. If people adopt better lifestyle choices or other simple interventions that reduce these and other issues, then how much of cancer might be avoided? Today's open access paper reports on study results suggesting the answer to that question is perhaps a larger fraction than one might have thought.
Mechanistic studies have shown that vitamin D inhibits the growth of cancer cells. Similarly, omega-3 may inhibit the transformation of normal cells into cancer cells, and exercise has been shown to improve immune function and decrease inflammation, which may help in the prevention of cancer. However, there was a lack of robust clinical studies proving the effectiveness of these three simple interventions, alone or combined.
Researchers conducted the DO-HEALTH trial: a three-year trial in five European countries (Switzerland, France, Germany, Austria, and Portugal) with 2,157 participants. The results show that all three treatments, vitamin D3, omega-3s, and simple home strength exercise program (SHEP), had cumulative benefits on the risk of invasive cancers. Each of the treatments had a small individual benefit but when all three treatments were combined, the benefits became statistically significant, and the researchers saw an overall reduction in cancer risk by 61%.
Generally healthy community-dwelling adults ≥70 years were recruited. The intervention was supplemental 2000 IU/day of vitamin D3, and/or 1 g/day of marine omega-3s, and/or a simple home strength exercise (SHEP) programme compared to placebo and control exercise. In total, 2,157 participants (mean age 74.9 years; 61.7% women; 40.7% with 25-OH vitamin D below 20 /ml, 83% at least moderately physically active) were randomized.
Over a median follow-up of 2.99 years, 81 invasive cancer cases were diagnosed and verified. For the three individual treatments, the adjusted hazard ratios (HRs) were 0.76 for vitamin D3, 0.70 for omega-3s, and 0.74 for SHEP. For combinations of two treatments, adjusted HRs were 0.53 for omega-3s plus vitamin D3; 0.56 for vitamin D3 plus SHEP; and 0.52 for omega-3s plus SHEP. For all three treatments combined, the adjusted HR was 0.39.