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DRI DIETARY REFERENCE INTAKES FOR Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride
appears to be less dependent on menopausal status. In summary, from available evidence, the calcium intake requirement for women does not appear to change acutely with menopause. appears to be less dependent on menopausal status. In summary, from available evidence, the calcium intake requirement for women does not appear to change acutely with menopause.
Lactose Intolerance. About 25 percent of adults in the United States have lactose intolerance and develop symptoms of diarrhea and bloating after ingestion of a large dose of lactose, such as the amount present in a quart of milk (about 46 g) (Coffin et al., 1994). Primary lactase deficiency begins in childhood and may become clinically apparent in adolescence. In adults, the prevalence of lactose intolerance, as estimated by a positive breath-hydrogen test, is highest in Asians (about 85 percent), intermediate in African Americans (about 50 percent), and lowest in Caucasians (about 10 percent) (Johnson et al., 1993a; Nose et al., 1979; Rao et al., 1994). Lactose-intolerant individuals often avoid milk products entirely although avoidance may not be necessary. Studies have revealed that many lactose-intolerant people can tolerate smaller doses of lactose, for example, the amount present in an 8 oz glass of milk (about 11 g) (Johnson et al., 1993b; Suarez et al., 1995). In addition, lactose-free dairy products are available. Although lactose-intolerant individuals absorb calcium normally from milk (Horowitz et al., 1987; Tremaine et al., 1986), they are at risk for calcium deficiency because of avoidance of milk and other calcium-rich milk products. Although lactose intolerance may influence intake, there is no evidence to suggest that it influences the calcium requirement.
Vegetarian Diets. Consumption of vegetarian diets may influence the calcium requirement because of their relatively high contents of oxalate and phytate, compounds that reduce calcium bioavailablity. In contrast to diets containing animal protein, however, vegetarian diets produce metabolizable anions (for example, acetate, bicarbonate) that lower urinary calcium excretion (Berkelhammer et al., 1988; Sebastian et al., 1994). On balance, lacto-ovovegetarians and omnivores appear to have fairly similar dietary calcium intakes (Marsh et al., 1980; Pedersen et al., 1991; Reed et al., 1994) and, on the same intakes, to have similar amounts of urinary calcium excretion (Lloyd et al., 1991; Tesar et al., 1992). BMD has been examined and compared in several cross-sectional studies of lactoovovegetarians and omnivores. Among premenopausal women, spinal BMD did not differ significantly in the two groups (Lloyd et al., 1991). Postmenopausal lacto-ovovegetarians are reported to have higher cortical bone mass than omnivores, as indicated by higher midradius density (Marsh et al., 1980; Tylavsky and Anderson,