Stress Effects on Chromium Nutrition of Humans and Farm Animals

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<strong>Stress</strong> effects on chromium nutrition of humans aad farm animals in parenteral nutrition fluids and extra chromium may not be required. Chromium content of parenteral nutrition fluids should be monitored routinely to prevent chromium accumulation especially in patients with impaired kidney function. Signs of Cr deficiency in humans are not limited to subjects on total parenteral nutrition. Improvements in glucose and(or) lipid concentrations have been observed in children with protein calorie malnutri- tion, adults and the elderly. Adults with low blood sugar, marginal to impaired glucose tolerance and diabetics have all been shown to respond to supplemental Cr (see review, Anderson, 1993). The signs of Cr deficiency in humans and experimental and farm animals shown to improve following supplemental Cr are listed in Table 1. Improvements following Cr supplementation may not be reversing signs of deficiency but rather therapeutic effects. For example, some early studies involving turkey poults (Steele and Rosebrough, 1979) and pigs (Steele et al., 1982) involved Cr added to the diet at 20-200 pg/kg of diet. Recent studies show beneficial effects in the nutritional range (100 to 1000 times lower) (Burton et al., 1992; Chang and Mowat, 1992; Page et al., 1993; Evock-Clover et al., 1993). However, true nutritional and therapeutic effects still need to be ascertained. Glucose, lipids and body composition of animals consuming stock diets containing presumably ample amounts of Cr (greater than 300 &kg) often improve when supplemented with Cr. However, the form of Cr used,may also be very important. Anderson et al. (1993) supplemented rats with nine different forms of Cr and demonstrated that some forms TabIe 1. Signs and symptoms of chromium deficiency. Function Animals Impaired glucose tolerance Human, rat, mouse, squirre1 monkey, guinea pig Elevated circulating insulin Human, rat, pig Glycosuria Human, rat Fasting hyperglycemia Human, rat, mouse Impaired growth Human, rat, mouse, turkey Hypoglycemia Human Elevated serum cholesterol and triglycerides Human, rat, mouse, cattle, pig Increased incidence of aortic plaques Rabbit, rat, mouse Increased aortic intimal plaque area Rabbit Neuropathy Human EncephaIopathy Human Cornea1 Iesions Rat, squirrel monkey Ocular eye pressure Human Decreased fertility and sperm count Rat Decreased longevity Rat, mouse Decreased insulin binding Human Decreased insulin receptor number HUmaIl Decreased Iean body mass Human, pig, rat Elevated per cent body fat Human, pig HumoraI immune response Cattle Morbidity Cattle Source: Adapted from Anderson, 1988. 268
R. A. Anderson of Cr including inorganic chromium chloride, were incorporated poorly into tissues. Chromium incorporation into rat tissues varied several-fold among the Cr compounds tested (Anderson et al., 1993). Therefore, total dietary Cr may be an inaccurate reflection of bioavailable Cr and a poor reflection of Cr nutritional status. <strong>Stress</strong> effects on human chromium nutrition <strong>Stress</strong>es shown to alter Cr nutrition are glucose loading, high simple sugar diets, lactation, infection, acute exercise, chronic exercise and physical trauma (Table 2, Anderson, 1988). Urinary Cr losses can be used as a measure of the Cr mobilized and lost since Cr is not reabsorbed in the kidney but is excreted via the urine (Doisy et al., 1971). Various forms of stress increase Cr losses and the degree of stress is roughly related to the amount of Cr lost in the urine. For example, mild aerobic exercise at 50% of V ozmax does not result in significant increases in urinary Cr losses while exercise at 90% of Vozmax does result in significant urinary Cr losses (Anderson et al., 1988). Running a 10 km race at near maximal capacity resulted in nearing a doubling of daily urinary Cr losses compared with a nonexercise day (Table 2, Anderson et al., 1982). Urinary Cr concentration was almost five-fold higher two hours following exercise compared with pre-exercise values. Anaerobic exercise also leads to increased Cr losses (Vincient et al., 1994). While acute strenuous aerobic and anaerobic exercise rest&s in significantly enhanced Cr losses, aerobic training leads to decreased basal Cr losses (Table 2; Anderson et al., 1988). Chromium values listed in TabIe 2 were all determined in our Iabora- tory at Beltsville by the same methods and can be compared directly. BasaI urinary Cr concentrations varied greatly prior to 1980 but accepted values are 0.12-0.22 kg/d for normal sedentary subjects. Decreased Cr losses observed in response to aerobic training may be an indication of decreased body Cr stores in response to repeated bouts of exercise. Lower basal losses in trained subjects may also be an adaptive response. If aerobic training led to increased Cr deficiency then people who are well-trained would be expected to display increased signs of Cr deficiency including impaired glucose tolerance and insulin resistance. However, this is not the case and aerobically trained individuals have improved glucose tolerance and insulin sensitivity (Rodnick et al., 1987). It is Table 2. <strong>Stress</strong> effects on urinary Cr losses of humans. <strong>Stress</strong> Urinary Cr, p&day Reference Basal 0.16 + 0.0’2 Anderson et al., 1982 Acute exercise 0.30 f 0.07 Anderson et al., 1982 Chronic exercise (training) 0.09 t 0.01 Anderson et al., 1988 Lactation 0.37 + 0.02 Anderson et al., 1993 High sugar diet 0.28 ST 0.01 Kozlovsky et al., 1986 Physical trauma 10.8 f 2.1 Bore1 et al., 1984
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Stress Effects on Chromium Nutrition of Humans and Farm Animals

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