Lactose intolerance associated with fractures of weight-bearing bones in Finnish women aged 38-57 years.
Lactose intolerance (LI) often results in decreased calcium intake. To test if long-term low intake of calcium affects bone strength, we examined fracture risks related to LI in women aged 38-57 years. The 11,619 Finnish women aged 47-56 years who responded to the baseline postal inquiry of the Kuopio Osteoporosis Risk Factor and Prevention Study in 1989 formed the study population. In all, 896 women reported LI and 1299 women reported a fracture in 1980-1989. Current intake of dairy calcium was lower in women with LI (570 mg/d) than in the other women (850 mg/d) (p < 0.0001). The fracture risk in general was slightly elevated in women with LI compared with the other women, with an odds ratio (OR) (95% CI) of 1.33 (1.09-1.62). However, the fractures at the three most common sites (wrist, ankle, and rib) were not related to LI. In contrast, fractures at the tibia and metatarsal were strongly related to LI with ORs of 3.31 (1.51-7.24) and 2.84 (1.47-5.50), respectively. The adjusted OR for nonankle lower body fractures combined was 2.15 (1.53-3.04), whereas that for all upper body fractures combined was 1.15 (0.88-1.54). The 10 women with LI and a tibial or metatarsal fracture showed a 19% lower femoral BMD than all the other women in the densitometry subsample of 3222 women (p < 0.001). Long-term premenopausal calcium deficiency differentially affects bones with weight-bearing nonankle bones being at the greatest risk of suffering reduced strength.