is, fat promotes the growth and de- 
velopment of already existing cancer 
cells but does not seem to initiate their 
formation. Human studies also seem 
to indicate that a diet high in poly- 
unsaturated fats may present a risk 
of cancer of the breast and colon. 
This emerging understanding of di- 
etary fat illustrates the general con- 
cept that although a minimum level 
of a nutrient is required for good 
health, an excess may increase the 
risk of cancer. Another observation 
made in the above rat studies was 
that the relationship between linoleic 
acid and total fat to their carcinogenic 
effects is not linear as in the generally 
accepted model for chemical carcino- 
genic initiators. In short, although in- 
creasing fat twofold, fourfold, or eight- 
fold does increase tumors, it doesn’t 
increase them by twofold, fourfold, 
or eightfold. According to our present 
knowledge, the relationship differs for 
each nutrient. 
The important message here is that 
a tumorigenic response is not neces- 
sarily exactly proportional to the level 
of nutrient intake. Also, estimations 
of cancer risks involving nutrient pro- 
moters such as linoleic acid differ 
from those involving carcinogenic ini- 
tiators. These initiators do behave in 
a linear manner, that is, there is a 
close mathematical relationship be- 
tween dosage and tumor production. 
A predictable number of cancer cases 
in a large population is a hypothetical 
possibility at low initiator intake lev- 
els, thus forcing the need for rigorous 
and perhaps absolute regulation. In 
the case of nutrients, not only is ab- 
solute regulation impractical but there 
may be good evidence that carcino- 
genic risk is near a minimum when 
the nutrients are consumed within 
their optimum range of intake. 
Other recent data concerning the 
possible relationship between nutri- 
ents and cancer deal with protein, se- 
lenium, and vitamin C. To begin with, 
the effect of protein intake on the 
carcinogenicity of aflatoxin, which is 
not a nutrient, illustrates the same 
concept as that just discussed for lin- 
oleic acid. In many species, aflatoxin 
is a potent initiator of liver cancer, 
but its total elimination from the hu- 
man food supply would be impossible 
without actually banning peanuts, 
corn, and the wide variety of products 
derived from them. (Fortunately, 
there has been excellent progress in 
this country in lowering the levels of 
aflatoxin sufficiently to make the sub- 
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FROM MERRIAM-WEBSTER® 
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Small Ad for 
a Big Tour of the Orient 
Japan Air Lines has 35 very special 
tours to the Orient. Come, let us take 
you to the Orient of your dreams. 
Here is but one example: 
Mandarin Orient, 19-24 days, 
$3197-3675. All tours visit Hong Kong, 
Peking, Shanghai and Canton. Some 
tours also visit Tokyo, Penang, 
Singapore, Bangkok as well as certain 
cities in China. All tours fully escorted 
and most meals are included. 
Rates based on double occupancy and economy air 
fare from the West Coast and are subject to change. 
Additional charge for June-October peak season. 
FcallToH Free" 
I 800-835-2246* Ext. 143 
I for free tour information, see your travel 
agent, or mail this coupon today. 
I Japan Air Lines, P.O. Box 10618 
| Long Island City, New York 11101 
JAL HAPPY HOLIDAYS 
| JAPAN AIR LINES 
I Dear JAL: I've read your small ad and I'd like 
more details of the tours I've checked. 
I □ Mandarin Orient (3005) 
| □ Other Happy Holidays Tours 
| Name 
| Address 
■ City State Zip 
Travel Agent NH 0581 
I ‘Continental CI S. only. In Kansas: 800-362-2421 
15 
