Understanding of the way osteoporosis relates to nutritional factors has been one of the successes of nutritional research over the last 50 years. However, as with all scientific research the gains that have been made have simply reflected common nutritional knowledge that was available to the practising nutritionist through books and anecdotal evidence. The traditional view is that osteoporosis is caused by calcium deficiency, and much of the early work on osteoporosis investigated the effects of calcium on bone tissue. While some beneficial effects for calcium supplements, along with vitamin D, have been reported, the studies are very inconsistent. This inconsistency suggests that calcium is not an effective treatment because calcium deficiency is not the cause of osteoporosis. In other words calcium is involved in the development of the disease, but the disease is not caused by a simple calcium deficiency. Clearly other factors are at play in the development of osteoporosis and understanding these is pivotal to effective treatment.
Hormones have also been extensively studies with regard osteoporosis. The rationale for such investigations is based on the sharp increase in the risk of developing osteoporosis after the menopause, an event characterised by a rapid change in the hormonal milieu of the body. In particular oestrogen levels drop significantly at this point, and this precipitous drop in oestrogen levels was investigated with regard its effects on bone density. Oestrogen replacement therapy has shown mixed results in the treatment of osteoporosis. While some rebuilding of bone tissue is evident, as would be expected from higher oestrogen levels, the detrimental side effects and long term usefulness of hormone therapy has been extensively questioned by experts. In particular, while the risk of osteoporosis decreases with oestrogen therapy, the risk of many forms of cancer increases. Oestrogen therapy can also cause psychological and behavioural changes. Both oestrogen and calcium in combination also show inconsistent results.
Although nutritionists have known for some time that acidification of the blood has detrimental effects on bone loss, it is only recently that science is catching up. Recent articles in mainstream journals have investigated the effects of blood pH on bone homeostasis and found that acidified blood, blood that has dropped in pH below its optimal range or fallen to the lower end of this range, is a primary driver of calcium loss from bones. This is because calcium is released (resorbed) from bone tissue in order to neutralise low blood pH thereby returning the range back to the optimal. Chronic consumption of foods that create acidified blood therefore causes a slow leaching of calcium from bone, and this creates a lower density bone tissue that develops the characteristic porosity seen in osteoporosis. Diets high in protein decrease blood pH and acidify blood because of the sulphur amino acids that protein contains, whereas plant based diets neutralise blood because of the high potassium content of plant foods.
Another factor that influences osteoporosis is weight bearing exercise. As we age, the amount of exercise we perform decreases and, in combination with hormonal changes, the stimulatory effects of stress on bone tissue diminishes significantly. As the requirement for strong bones decreases, the bones responded by restructuring themselves in a weaker configuration. Applying a stress to the bones is pivotal in creating and maintaining a strong skeleton, and this can be achieved only through weight bearing exercise. Many studies have shown benefits to exercise, but those which have used resistance training have shown by far the best results. In other words the larger the stress on the bones the quicker and more fully they respond by increasing their density. Heavy and frequent resistance training is therefore a requirement for anyone wishing to maintain bone density into old age. This may not necessarily require a gym, lifting, gardening, digging, cutting and jumping, all provide a large stressor to bones and joints.