Negative dietary practices

Alcohol

Moderate alcohol intake is not thought to be harmful to bone. In contrast, higher levels of alcohol intake – more than two standard units of alcohol daily – are been found to produce a significant increase in the risk of hip and other osteoporotic fractures (28).

Excessive alcohol intake is known to have direct detrimental effects on bone-forming cells and on the hormones which regulate calcium metabolism. In addition, chronic, heavy alcohol consumption is associated with reduced food intake (including low calcium, vitamin D and protein intakes) and overall poor nutritional status, which will in turn have adverse effects on skeletal health. Excess alcohol use also increases the risk of falling, thereby increasing the opportunity for fracture.

Weight loss diets and eating disorders

Being underweight is a strong risk factor for osteoporosis. Very low body weight is associated with lower peak bone mass development in the young, and increased bone loss and risk of fragility fractures in older persons. In a large data analysis of 60,000 men and women worldwide (29), the risk of hip fracture almost doubled in people with a body mass index (BMI) of 20 kg/m2, compared with people with a BMI of 25 kg/m2.

Lactose maldigestion and intolerance

When people are unable to digest all the lactose they have eaten, they are said to have lactose maldigestion. It results from a deficiency in the enzyme lactase, produced in the small intestine, which is responsible for breaking down lactose into simpler sugars, which are then absorbed by the body.

Lactose maldigestion does not necessarily result in lactose intolerance. Most people with lactose maldigestion can still consume at least some lactose-containing foods without experiencing symptoms of lactose intolerance. Lactose maldigestion and intolerance are more common among Asians and Africans than among people of northern European descent, although supplementation studies in postmenopausal Chinese women demonstrated that additional milk intake was well tolerated and slowed the rate of bone loss (35, 36). Lactose intolerance is a potential risk factor for bone loss and osteoporosis, due to the avoidance of dairy products and possibility of lower calcium intakes.

Carbonated beverages

Concerns have been raised that consumption of carbonated soft drinks, notably cola drinks, may adversely affect bone health. Although a few observational studies have shown an association between high carbonated beverage consumption and either decreased BMD (37) or increased fracture rates (38) in teenagers, there is no convincing evidence that these drinks adversely affect bone health.

It has been suggested either the phosphorus content or the caffeine content of cola beverages may have a negative impact on calcium metabolism, but this has not been demonstrated in experimental studies (39). Phosphorus is a key constituent of bone mineral along with calcium, and there is no evidence for detrimental effects of phosphorus intake on bone health or osteoporosis risk in healthy individuals (40).

If there is any negative effect of carbonated beverages, it is more likely to be due to the fact that these drinks displace milk in the diet, and hence impact on calcium intake.

Salt

A high sodium (salt) intake promotes urinary calcium excretion, and is therefore considered to be a risk factor for bone loss. The DASH bone study showed that lowering sodium intake was beneficial for bone metabolism, but this was in the context of other dietary changes (26). Studies in teenage girls have shown that salt loading decreased the amount of calcium taken up by the bones, apparently via a decrease in calcium absorption (42). One study showed a small association between sodium excretion (a measure of salt intake) and bone loss in postmenopausal women (43). However, there is no clear evidence that lowering sodium intakes would reduce fracture rates in populations, although there may be other public health benefits from such a strategy, primarily a reduction in population blood pressure levels which in turn could reduce the risk of stroke and cardiovascular diseases.

Caffeine

Caffeine is often implicated in the development of osteoporosis, but again without any convincing evidence that this is the case (44). Caffeine does produce a small increase in urinary calcium excretion and a very small decease in calcium absorption, but the body appears to balance this out by reducing calcium excretion later in the day, therefore the net effect is negligible (39, 44). Studies examining the effects of caffeine on rates of bone loss in postmenopausal women showed that as long as calcium intake was sufficient (above about 800 mg/day), caffeine intake had no detrimental effects. However, if calcium intake was low, caffeine intake equivalent to about 3 cups of brewed coffee per day was associated with more bone loss (45).

References

28.Kanis JA, Johansson H, Johnell O, et al. (2005) Alcohol intake as a risk factor for fracture. Osteoporos Int 16:737-42.
29.De Laet C, Kanis JA, Oden A, et al. (2005). Body mass index as a predictor of fracture risk: a meta-analysis. Osteoporos Int 16:1330-38.
35.Lau EM, Woo J, Lam V, et al. (2001) Milk supplementation of the diet of postmenopausal Chinese women on a low calcium intake retards bone loss. J Bone Miner Res 16:1704-09.
36. Chee WS, Suriah AR, Chan SP, et al. (2003) The effect of milk supplementation on bone mineral density in postmenopausal Chinese women in Malaysia. Osteoporos Int 14:828-34.
37.McGartland C, Robson PJ, Murray L, et al (2003) Carbonated soft drink consumption and bone mineral density in adolescence: the Northern Ireland Young Hearts project. J Bone Miner Res 18:1563-69.
38.Wyshak G (2000) Teenaged girls, carbonated beverage consumption, and bone fractures. Arch Pediatr Adolesc Med 154:610-13.
39.Heaney RP and Rafferty K (2001) Carbonated beverages and urinary calcium excretion. Am J Clin Nutr 74:343-47.
40.Heaney RP (2004) Nutrients, interactions, and foods: the importance of source. In Nutritional Aspects of Osteoporosis, 2nd edn, Eds. P. Burckhardt, B. Dawson-Hughes, RP Heaney, Elsevier Academic Press.
41.Meunier PJ, Jenvrin C, Munoz F, et al. (2005) Consumption of a high calcium mineral water lowers biochemical indices of bone remodelling in postmenopausal women with low calcium intake. Osteoporos Int 16:1203-09.
42.Wigertz K, Palacios C, Jackman LA, et al. (2005) Racial differences in calcium retention in response to dietary salt in adolescent girls. Am J Clin Nutr 81:845-50.
43.Devine A, Criddle RA, Dick IM, et al. (1995) A longitudinal study of the effects of sodium and calcium intakes on regional bone density in postmenopausal women. Am J Clin Nutr 62:740-45
44.Heaney RP (2002) Effects of caffeine on bone and the calcium economy. Food Chem Toxicol 40:1263-70.
45.Harris SS and Dawson-Hughes B (1994) Caffeine and bone loss in healthy postmenopausal women. Am J Clin Nutr 60: 573-78.