Page 81 - Special Issue: Healthy Baby

Breastfeeding issued a joint statement in which The Weston A. Price Foundation recommends 2,000 IU per day of
they overturned the 40-year position of the Acad- vitamin D from cod liver oil, and small additional amounts from fatty fish,
emy advocating 400 IU in favor of adopting the shellfish, butter, and lard. Although no studies have directly assessed the
lower so-called “overestimate” of the Institute of use of this dose during pregnancy, a study of over 10,000 infants in Finland
Medicine. 34 conducted between 1966 and 1997 showed that direct supplementation of
In the second part of this statement, the Acad- 2,000 IU per day to infants in the first year of life virtually eradicated the
emy directed mothers to keep their infants out of risk of type 1 diabetes over the next 30 years. 35
the sun, dress them in protective clothing, and
liberally cover them in sunblock. In the last part VITAMIN K
of the statement, it emphasized that breast milk Compared to vitamins A and D, very little is known about the role of
is deficient in vitamin D—making no mention of vitamin K in embryonic and fetal development. The enzyme that uses it
the fact that the low intake of vitamin D during to activate vitamin K-dependent proteins first shows up in the skeletal and
pregnancy and lactation that it advocates and the nervous tissue of the embryo. Two vitamin K-dependent proteins, bone
36
practice of keeping infants out of the sun are the Gla protein and matrix Gla protein, are present in the first trimester. These
37
precise factors responsible for low vitamin D lev- proteins help lay down calcium salts in bone tissue and keep calcium out
els in breast milk and infant vitamin D deficiency. of the soft tissues where it does not belong.

VITAMIN A AND BIRTH DEFECTS

The claim that intakes of vitamin A over 10,000 IU per day can increase the risk of birth defects can be traced back
to a 1995 paper published by a group of researchers led by Dr. Kenneth Rothman of Boston University. The researchers
21
followed almost 23,000 women over the course of their pregnancies and found that women who consumed more than
10,000 IU of vitamin A during the first trimester gave birth to offspring with a 2.4-fold greater risk of total birth defects
and a 4.8-fold greater risk of cranial-neural-crest defects (a rather broad group of defects whose classification is contro-
versial).
Among the 188 women who consumed this amount of vitamin A from “food” alone, there was an 80 percent
increase in the risk of total birth defects and two times the risk of cranial-neural-crest defects. Because there were so
few women consuming vitamin A from “food” alone, however, the researchers could not conclusively distinguish the
association from the effect of chance.
This study has a number of important flaws. Most of the vitamin A came from multivitamins. The authors did not
distinguish between various food sources—and most “food” vitamin A comes from fortified breakfast cereals. Three
groups of experts wrote to the journal questioning the authors’ classification of cranial-neural-crest defects. 22,23,24 Perhaps
most important, the authors may have underestimated the rate of certain types of birth defects. The rate of total birth
defects among the 20,000 women consuming less than 10,000 IU was only 1.5 percent; by contrast, the generally ac-
cepted background rate is 3-4 percent. The rate of defects among the 3,000 women consuming more than 10,000 IU
of vitamin A was 3 percent—on the lower end of normal. 24
The most important objection to this study is the fact that it conflicts with all the other evidence:
• An earlier 1990 study conducted in Spain found that among 25,000 births, doses of vitamin A over 40,000 IU
per day carried a 2.7-fold higher risk of birth defects, but doses of vitamin A up to 20,000 IU or between 20,000
and 40,000 IU both carried a 50 percent lower risk of birth defects compared to no supplementation. 25
• A 1996 study of 522,601 births found that the children of women supplementing with at least 10,000 IU of vitamin
A in addition to a multivitamin had a lower risk of birth defects than those of women who did not supplement,
although the association could not be distinguished from the effect of chance. 26
• A 1997 study of 1,508 births found no relationship between birth defects and use of vitamin A supplements,
fortified breakfast cereals, organ meats or liver. 27
• A 1999 prospective study of 311 mothers who consumed between 10,000 and 300,000 IU of vitamin A in the first
trimester and a similarly sized group that did not supplement with vitamin A found no evidence of an increased
risk of major malformations with increasing dose. The median dose was 50,000 IU. The group as a whole had
a 50 percent lower risk of major malformations than those who did not supplement, and there were no major
malformations in offspring born to mothers consuming more than 50,000 IU.
The preponderance of the evidence clearly favors the view that 20,000-25,000 IU of vitamin A during pregnancy
is safe and may even reduce the risk of birth defects. 63

Wise Traditions 79