Experiments That Changed Nutritional Thinking - TUUM EST

1048S
SUPPLEMENT
TABLE 1
The first experiment on the effect of diet on radiation mortality in guinea pigs1
Radiation dose (R)
100 150 200 250 300 350 400 500
mortality, %
Cabbage — — 0 10 25 50 75 100
Beets 2.5 — 100 — 100 — 100 —
1 Data from Lourau and Lartigue (1950).
in the two groups, at equal radiation doses, animals fed beets control group would have allowed them to distinguish between
had more severe and widespread hemorrhages than those fed their two explanations (toxic substances in beets vs. protective
cabbage.
substances in cabbage).
The authors proposed two explanations for the dietary effect Spector and Calloway used an oat and bran control diet and
on radiosensitivity. They suggested that 1) cabbage may con- the control diet supplemented with beets, cabbage or broccoli.
tain substances that protect against radiation damage, such as They irradiated their four groups of guinea pigs with a radiation
vitamins P and C; or 2) beets may contain substances that dose of 400 R. Their results are shown in Table 3. Although
become toxic after irradiation. They preferred the second explanation,
beet consumption did not affect mortality, consumption of
that beets were toxic to irradiated guinea pigs. This either cabbage or broccoli significantly reduced mortality from
was supported by the observation that the LD 50 for the animals irradiation. Thus, they proved that Lourau and Lartigue were
consuming beets was about 150 R, considerably lower than incorrect in their conclusion that beets contained a toxic substance
the usually reported LD 50 of 250 R.
and that Duplan was correct as to the protective effects
A few years later, M. Jean-Francois Duplan showed that in of cabbage.
fact, Lourau and Lartigue’s first explanation was correct, that Calloway and colleagues went on to investigate the sub-
cabbage did offer protection against radiation damage (Duplan stance conferring the protective effects (Calloway et al. 1963).
1953). Duplan studied 70 male guinea pigs fed oat and bran Because the basal diet was devoid of vitamin A, and animals
diets. The test diets were supplemented with either cabbage consuming this diet were known to become vitamin A deficient,
or carrots in this study, and the animals received a single
they suggested that sources of vitamin A might be able
radiation dose.
to decrease the radiosensitivity of guinea pigs. Their results
The results of Duplan are shown in Table 2. For a given are shown in Table 3. In this experiment, they confirmed
radiation dose, the animals consuming cabbage had much previous findings that both cabbage and broccoli lowered mortality
lower mortality than those consuming carrots. He saw no differences
in irradiated animals. They found that a number of other
in lesions, but he did note that the animals consuming b-carotene–containing foods also exerted some beneficial effects.
carrots lost much more weight than those consuming cabbage.
Mortality after 20 d was significantly lowered by concarrots
Duplan’s results suggested that Lourau and Lartigue may sumption of the b-carotene–containing vegetables that they
have been incorrect in concluding that beets contained a toxic tested. Beets, apples and white potatoes had no effect. Supple-
substance. Rather than concluding that carrots contained a mentation with all essential vitamins reduced mortality somewhat,
toxic substance, Duplan concluded that cabbage lowered the
but not to the same degree as supplementation with
radiosensitivity of guinea pigs. He speculated that the radioprotective
substances may have been antioxidant goitrogens present
in the cabbage.
Spector and Calloway (1959) continued this investigation
TABLE 3
of the dietary factors that protect against radiation damage. Further experiments on the effect of diet on radiation
They very importantly noted that Lourau and Lartigue did not
mortality in guinea pigs
have a control group in their experiment. The addition of a
Mortality at 20 d after irradiation
with 400 R
TABLE 2
The second experiment on the effect of diet on radiation
mortality in guinea pigs1
Radiation dose (R)
300 500 1000
mortality, %
Cabbage 0 6.5 87.5
Carrots 50 86 —
1 Data from Duplan (1953).
Spector and
Calloway et al.
Supplement Calloway (1959) (1963)
mortality, %
None 100 97
Beets 90 —
Cabbage 50 54
Broccoli 35 42
Alfalfa 0
Mustard greens 12
Green beans 31
Lettuce 44
All vitamins 72
/ 4p09$$0062 04-07-97 14:02:12 nutras LP: J Nut May Suppl
Downloaded from jn.nutrition.org by on June 3, 2010