However, the data are still very sparse, and the DRI for this age group relies on one study, albeit a well-controlled and carefully analyzed study.
The natural process of bone loss begins to manifest itself in the latter stages of adulthood. It begins earlier for women than for men as a result of the onset of menopause, which usually occurs when women reach 50 to 55 years of age. By the time both men and women have reached 70 or more years of age, each are experiencing bone loss. However, women—who have been undergoing the loss longer—are more at risk for adverse consequences. It is important to underscore that the goal of calcium intake during these life stages is to lessen the degree of bone loss; calcium intake at any level is not known to prevent bone loss.
Although calcium absorption (active calcium transport) has been reported to decrease with age (Avioli et al., 1965; Bullamore et al., 1970; Alevizaki et al., 1973; Gallagher et al., 1979; Tsai et al., 1984), it is challenging to consider higher calcium intake as a remedy given that calcium intake must be extremely high to have an effect on calcium uptake via passive absorption (i.e., paracellular transport, see Chapter 2).
The relative lack of data pertaining to bone changes in men as they age has received comment (Orwoll et al., 1990). It has been pointed out that cross–sectional data suggest that, overall, the rate of bone loss in men is substantially slower than that in women, and men have a lower incidence of fractures (Khosla et al., 2008); perhaps this accounts for the lack of research focused on this group. The limited available trials and observation studies (e.g., Osteoporotic Fractures in Men [MrOS] study) concerning bone health focus on men older than the 5 through 70 year age range (usu-