Evrovski, 2000; Cole et al., 1992), and this raises questions concerning sulfate requirements during pregnancy, particularly in situations where the mother is on a medication, such as acetaminophen, that is known to deplete sulfate (Morris and Levy, 1983).

Sulfate intake (as well as sulfate produced via amino acid turnover) typically exceeds the need for 3′-phosphoadenosine-5′-phosphosulfate biosynthesis, as evidenced by maintenance of normal levels of urinary excretion of sulfate (Cole and Evrovski, 2000) when sulfur amino acids are adequate. Recommended intakes have already been established for sulfur amino acids, which would thus cover the need for inorganic sulfate (IOM, 2002/2005). Given these two points, neither an Estimated Average Requirement (and thus a Recommended Dietary Allowance) nor an Adequate Intake for sulfate is established.

Approximately 19 percent of total sulfate comes from ingested inorganic sulfate from foods and 17 percent of total comes from inorganic sulfate in drinking water and beverages (Table 7-1). Many other sulfur compounds in food can yield inorganic sulfate as a result of degradation or turnover. Among organic compounds, methionine and cysteine in food proteins, glutathione in both animal and vegetable products (Wierzbicka et al., 1989), taurine in animal-source foods, lanthionine (a cross-linked sulfur amino acid produced when protein-bound cysteine undergoes heat treatment at an alkaline pH), and sulfated glycosaminoglycans in both plant-and animal-derived foods are important contributors of organic sulfate, providing the remaining approximately 64 percent of total sulfate available for body needs.

Other organic sulfur compounds are ingested in certain situations. Several drugs contain sulfur, and several cysteine derivatives are used in certain clinical situations. For example, N-acetyl-L-cysteine is used as a mucolytic agent for treating sepsis, respiratory diseases, and various autoimmune deficiency diseases (Baker and Wood, 1992; Kelly, 1998). Sulfur-containing D-penicillamine or dimercaptopropanol is used for treating the copper toxicity problems seen in Wilson’s disease (Smithgall, 1985). Also, small quanti-

Front Matter (R1-R20)

Summary (1-20)

1 Introduction to Dietary Reference Intakes (21-36)

2 Overview and Methods (37-49)

3 A Model for the Development of Tolerable Upper Intake Levels (50-72)

4 Water (73-185)

5 Potassium (186-268)

6 Sodium and Chloride (269-423)

7 Sulfate (424-448)

8 Applications of Dietary Reference Intakes for Electrolytes and Water (449-464)

9 A Research Agenda (465-470)

Appendix A: Glossary and Acronyms (471-476)

Appendix B: Origin and Framework of the Development of Dietary Reference Intakes (477-484)

Appendix C: Predictions of Daily Water and Sodium Requirements (485-493)

Appendix D: U.S. Dietary Intake Data from the Third National Health and Nutrition Examination Survey, 1988 1994 (494-517)

Appendix E: U.S. Dietary Intake Data for Water and Weaning Foods from the Continuing Survey of Food Intakes by Individuals, 1994 1996, 1998 (518-526)

Appendix F: Canadian Dietary Intake Data for Adults from Ten Provinces, 1990 1997 (527-533)

Appendix G: U.S. Water Intake and Serum Osmolality Data from the Third National Health and Nutrition Examination Survey, 1988 1994 (534-536)

Appendix H: U.S. Total Water Intake Data by Frequency of Leisure Time Activity from the Third National Health and Nutrition Examination Survey, 1988 1994 (537-545)

Appendix I: Dose-Response Effects of Sodium Intake on Blood Pressure (546-557)

Appendix J: Serum Electrolyte Concentrations NHANES III, 1988-94 (558-563)

Appendix K: Options for Dealing with Uncertainties (564-568)

Appendix L: Acknowledgments (569-571)

Appendix M: Biographical Sketches of Panel Members (572-576)

Index (577-618)