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0.4 g/day). In the absence of information to the contrary, it is assumed that the efficiency of conversion of dietary potassium to milk produced is almost 100 percent. Therefore, the AI for potassium during lactation is set at 5.1 g (130 mmol)/day (4.7 g + 0.4 g/day).

Potassium AI Summary, Lactation

14–18 years

5.1 g (130 mmol)/day of potassium

19–30 years

5.1 g (130 mmol)/day of potassium

31–50 years

5.1 g (130 mmol)/day of potassium

Special Considerations

Very Low Carbohydrate, High Protein Diets

Low-grade metabolic acidosis occurs with very low carbohydrate, high protein diets consumed by some individuals to promote and maintain weight loss. These diets, which may be adequate in potassium due to the high protein content, are inadequate as a source of alkali, because fruits are often excluded in these diets.

Over a 6-month period in which the metabolic consequences of such a diet were investigated in 51 overweight or obese volunteers, weight loss occurred, but the concomitant and intended ketosis led to an ongoing low-grade, metabolic acidosis, as judged by decreases in serum bicarbonate of 2 to 3 mmol/L (still in the normal range), as well as a persistent increase in urinary excretion of calcium of approximately 80 mg/day (Westman et al., 2002).

In a 6-week study of the metabolic effects of a low carbohydrate/high protein diet ingested by 10 adult subjects, a doubling of urinary net acid excretion was attended by a 50 percent increase in urinary excretion of calcium, which was not compensated by a commensurate increase in fractional intestinal calcium absorption (Reddy et al., 2002). Failure of intestinal compensation has been consistently demonstrated for acidosis-induced urine calcium losses (Breslau et al., 1988; Lemann et al., 1966).

Urinary excretion of citrate and serum osteocalcin also concurrently decreased with the increase in urinary excretion of calcium (Reddy et al., 2002). It was concluded that the diet delivered a marked acid load to the kidney, increased the risk of stone formation, led to negative calcium balance, and may have increased bone loss. Those diets that concomitantly restrict the intake of fruits like oranges, bananas, and grapes also restrict the intake of bicarbonate precursors like citrate, a restriction which would amplify the



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