Chemistry Reference
In-Depth Information
factor critical for B
12
internalization and absorption in the ileal mucosa).
Untreated vitamin B
12
deficiency results in potentially irreversible neurolo-
gical damage and life-threatening anemia. Infants fed predominantly human
milk usually demonstrate clinical signs of B
12
deficiency if the mother has
been a strict vegetarian for at least 3 yr or has untreated pernicious anemia
(Food and Nutrition Board: Institute of Medicine, 1998). Humans ordinarily
obtain vitamin B
12
from animal foods, mainly meat, fish and poultry. Milk
and milk drinks are the second category contributing the most B
12
to the diets
of women. However, there is some evidence that boiling milk for 10 min
reduces B
12
content by
50%. This practice may of particular concern for
certain lactovegetarians. For example, boiling milk was described as a com-
mon cooking practice among Hindu women in the United Kingdom (Stewart
et al., 1970).
10.14.
Fluoride
Unequivocal or specific signs of fluorine deficiency have not been described
for higher animals or humans (Nielsen, 2006). Fluoride, the ionic form of
fluorine, has a well-established beneficial function in humans; it protects
against pathological demineralization of calcified tissues as a pharmacologi-
cal agent (Food and Nutrition Board: Institute of Medicine, 1997). Fluoride
inhibits tooth enamel degradation by two separate mechanisms. Uptake of
fluoride by tooth enamel crystallites and the formation of fluorhydroxyapa-
tite during pre-eruptive tooth development reduce the risk of dental caries;
the fluorhydroxyapatite is less acid-soluble than hydroxyapatite. After erup-
tion, fluoride protects tooth enamel by reducing acid production by plaque
bacteria and increasing the rate of enamel re-mineralization during an acido-
genic challenge (Sieck et al., 1990). Sodium fluoride (NaF) has been shown
repeatedly and reproducibly to increase spinal bone mass in a dose-dependent
manner. Yet, despite numerous studies, NaF has never been convincingly
demonstrated to reduce the vertebral fracture rate in established spinal
osteoporosis (Kleerekoper and Mendlovic, 1993).
Although fluoride intakes by fully breast-fed infants is low, fluoride
intakes by partially breast-fed infants and by formula-fed infants is highly
variable, depending primarily on the fluoride content of the water used to
dilute concentrated liquid or powdered infant formula products. Prolonged
exposure to high intakes of fluoride during infancy is much more common
now than in the past because of a trend toward more extended feeding of
formula (Fomon and Ekstrand, 1999). Infants fed human milk consume
about 0.01 mg/d fluoride but those fed a formula reconstituted with fluori-
dated water may receive as much as 1.0 mg/d. For infants aged 0-6 months,
