Page 26 - Spring2008

Not all vegetarians develop overt health from yellow-orange vegetables possessed the
problems in such a short length of time from same activity. These vegetables contain beta-
12
abandoning animal foods and some—especially carotene and other carotenoids that humans and
those who eat eggs, milk, or occasional fi sh and animals can convert into retinol, the functional
shellfish—may maintain good health for decades. form of vitamin A found in animal products.

A strictly vegetarian diet, however, clearly lacks In 1949, Hume and Krebs induced vitamin A

nutritional qualities that an omnivorous diet pos- deficiency in three human subjects; they treated
sesses. If the people most sensitive to defi ciencies one with retinol and treated the other two with
of these nutrients suffer the types of problems a concentrated dose of beta-carotene dissolved
that I did, those who are less sensitive and not in oil. They concluded that 3.8 units of carotene
suffering obvious problems may nevertheless fail are required to produce one unit of retinol. A
to achieve optimal health without optimal levels similar experiment conducted in 1974 established
of nutrients from animal sources. a conversion factor of two and several others
This article will discuss those nutrients, established conversion factors between two and
13
their functions and their sources, starting at the four.
beginning of the alphabet with vitamin A. In 1967, the United Nations Food and Agri-
culture Organization (FAO) and World Health Or-
VITAMIN A ganization (WHO) released a joint recommenda-
The roles of vitamin A in vision, growth, tion stipulating that six units of beta-carotene and
immunity, reproduction and the differentiation of twelve units of other carotenoids with vitamin A
cells and tissues are well known. Vitamin A also activity should be considered equivalent to one
1
plays a number of lesser known functions: it is a unit of retinol, a recommendation they renewed
powerful antioxidant in cell membranes, 2,3,4 pro- unchanged in 1988. This led H.P. Oomen, the
tects against environmental toxins, contributes prominent researcher who fi rst highlighted the
5
to the regulation of bone growth, protects against problem of vitamin A defi ciency in the Third
6
asthma and allergies, prevents the formation of World, to write, “The whole procedure of vita-
7,8
kidney stones, and protects against fatty liver min distribution would be wholly superfl uous if
9
disease. adequate carotene were present in the children’s
10
“Fat-soluble A” originally referred to the diet.” Oomen believed that just 30 grams per day
ability of butter or egg yolks to support weight of dark green leafy vegetables would be suffi cient
gain and prevent mortality in laboratory rats. One in and of itself to provide adequate vitamin A to
of the discoverers of vitamin A, Elmer Verner undernourished children. 14
McCollum, initially attributed the ability of cod Yet in the 1990s, this view began to change.
liver oil to treat both the eye disease xerophthal- In 1994, Suharno and others observed that preg-
mia and the bone disease rickets to its content of nant Indonesian women were consuming enough

In 2003, this vitamin. Eventually, researchers recognized carotenes to yield three times the recommended
vitamins A and D as two different vitamins be-
amount of vitamin A based on the WHO’s con-
Tang and cause heating cod liver oil destroyed its ability version factor, yet large numbers of them were
colleagues to cure xerophthalmia but not its ability to cure suffering from marginal vitamin A defi ciency.
showed that rickets. Although they would determine over time Subsequent intervention studies aimed at Indo-
the fact that the vitamin D content of butter de-
nesian school children and breastfeeding women
even the pends on the season and the condition of the cows in Vietnam found that the conversion factor for
efficiency of producing it, the observation that both cod liver carotenes to vitamin A in vegetables was 26 and
beta-carotene oil and butter could cure xerophthalmia but only 28 respectively, and 12 when the carotenes were
cod liver oil could cure rickets also contributed to consumed in fruit. In 2002, the U.S. Institute of
dissolved in the differentiation of vitamins A and D. Vitamin Medicine (IOM) established a conversion factor
11
oil had been A, then, was originally discovered because of the of 12 for beta-carotene, 24 for other carotenoids
grossly over- life-promoting properties of three animal fats. with vitamin A activity, and two for beta-carotene
Research conducted soon after, however, dissolved in oil. West and others criticized the

estimated. showed that the yellow lipid fraction extracted selective use of studies employed by the IOM,
26 Wise Traditions SPRING 2008