Vitamin B9 (folic acid) may strengthen the bones

Folic acid prevents spina bifida which is a serious and relatively frequent congenital malformation. Moreover, it is assumed that the vitamin counteracts coronary thrombi, strokes, and other sequelae from atherosclerosis. Folic deficiency is quite a common suffering. One of the results of folic acid deficiency is that the blood level of the amino acid homocysteine is higher than normal.
In the Netherlands, a group of 2,406 people above the age of 55 located in Rotterdam and Amsterdam were followed over a period of up to nine years.
In the American study which was part of the well-known Framingham study, 1,999 elderly people participated and were followed for 15 years. In addition to fractures, a large number of other significant factors in the development of osteoporosis were registered: Smoking habits, age, height and weight, consumption of coffee and alcohol, calcium- and vitamin D intake, oestrogen supplements, etc.
The two studies demonstrated that a high level of homocysteine was linked to an increased risk of suffering hip fractures. Both studies showed that people who belong to the top 25% with regards to high homocysteine levels in their blood have twice as large a risk of breaking their hip as the ones who have much lower levels of homocysteine.
Several conditions point towards a cause and effect relationship here. For example, it was statistically rejected that the risk was related to and biased by other known causes of osteoporosis, such as smoking, a lack of dietary calcium, etc. It is also known that osteoporosis is a pronounced phenomenon in the hereditary disease homocystinuria in which the levels of homocysteine are particularly high. Finally, it has been demonstrated in laboratory experiments that homocysteine weaken the cross-links in the wickerwork of connective tissue around which the bones are built.
According to the Dutch results, a high level of homocysteine - and thereby a resulting lack of folic acid - might be the cause of approximately 19% of all hip fractures!
References:
1. Van Meurs Joyce B J et al. Homocysteine levels and the risk of osteoporotic fracture. N Engl J Med 2004;350:2033-41
2. Mc Lean Robert R et al. Homocysteine as a predictive factor for hip fracture in older persons, N Engl J Med 2004;350:2042-9
3. (Editorial) Raisz LG. Homocysteine and osteoportic fractures - culprit or bystander? N Engl J Med 2004;350:2089-90.