Chemistry Reference
In-Depth Information
nickel supplementation when dietary nickel is low, and nickel can alleviate
vitamin B
12
deficiency in higher animals. No chronic nickel toxicosis signs
caused by oral intake have been reported for humans (Food and Nutrition
Board: Institute of Medicine, 2001; Nielsen, 2006). Toxicosis through oral
intake is limited to a few case reports of acute affects resulting from the
ingestion of high doses of soluble nickel salts; this resulted in nausea, abdom-
inal pain, diarrhea, vomiting and shortness in breath. Nickel-sensitive indi-
viduals may show a contact dermatitis-like reaction after a high intake (i.e.,
0.6 mg) of soluble nickel after fasting.
The FNB (Food and Nutrition Board: Institute of Medicine, 2001) set
no RDA or AI for nickel, or an UL for infants; however, an UL of 0.2 mg/d
was set for children aged 1-3 yr. Animal data suggest that intakes near 100 mg
nickel per day may be beneficial (Nielsen, 2006). Typical daily dietary intakes
for nickel are 70-400 mg/d (Food and Nutrition Board: Institute of Medicine,
2001).
Nickel is widely distributed in tissues at concentrations generally
between 0.01 and 0.2 mg/kg wet weight (Eder and Kirchgessner, 1997; Nielsen,
2006). At 38 d postpartum, the mean nickel concentration in human milk was
reported to be 1.2 mg/l (Casey and Neville, 1987). However, another report
indicated that human milk contained a much higher concentration of nickel of
41 mg/l (Anke et al., 1993). Mature bovine milk was found to contain 10-30 mg
nickel/l (Casey, 1977; Anke et al., 1993). Thus, dairy products could supply a
significant proportion of the daily intake of nickel. This suggestion is supported
by the finding that Canadian infants (age 0-12 months) had a nickel intake of
38 mg/d supplied by both human milk and formula consumption (Dabeka,
1989).
10.19.
Silicon
Although silicon deprivation has been reported to produce aberrant metabo-
lism of connective tissue and impaired immune function, silicon is still not
generally accepted as an essential nutrient for higher animals. Recently,
however, dietary silicon correlated positively and significantly with bone
mineral density at all hip sites in men and pre-menopausal women in a large
cross-sectional, population-based study (Jugdaohsingh et al., 2004). No acute
oral silicon toxicity signs have been identified for humans. Extremely high
amounts of silicon are needed to have just relatively minor effects on growth
in experimental animals (Committee on Minerals and Toxic Substances in
Diets and Water for Animals, 2005). Silica stones have been found in people
on long-term antacid therapy with magnesium trisilicate (Food and Nutrition
Board: Institute of Medicine, 2001). The FNB did not set an UL for silicon
