Poultry Science Florida Agricultural
Mimeograph Series No. PY 72.2 Experiment Station
500 Copies Gainesville, Florida
THE RELATIONSHIP OF ANIMAL FOOD PRODUCTS AND CHOLESTEROL
TO THE INCIDENCE OF HEART DISEASE
S. T. McCready
Atherosclerosis is a condition in which certain areas on the inner
wall of the arterial blood vessels become covered with deposits of fatty-
like material that tend to restrict normal blood flow. Coronary heart
disease (CHD) is a specific example of atherosclerosis and is the nation's
number one killer. The relationship between atherosclerosis and choles-
terol was first reported around the turn of the century by researchers who
fed cholesterol to rabbits which subsequently developed atherosclerosis.
Succeeding test work up to the present has revealed that test animals
respond differently to dietary cholesterol. Rabbits are very sensitive
to dietary cholesterol, while laboratory rats can tolerate extremely high
levels of cholesterol in the blood before atherosclerosis developed (Pope,
1971a). However, this initial report concerning atherosclerosis of rabbits
has been the primary basis for attributing CHD to cholesterol levels in the
diet of man.
Various research reports have linked cholesterol to hormone production,
formation of vitamin D in the skin, cell function, bile acid formation,
nerve impulse, fatty acid transport in the blood, and, according to one
report, possibly even resistance to disease. Cholesterol's necessity in
the body is evidenced by its constant formation (1500 to 2000 mg. daily)
from ingested food regardless of cholesterol content (Pope, 1971a).
COMMERCIALISM OF CHOLESTEROL
The public today is probably no better informed about the effects
of diet on atherosclerosis than they were 20 years ago. The American
Heart Association, along with commercial interests whose profits center
around food products incorporating polyunsaturated fats and oils, actively
promote the polyunsaturated fat diet as a definitive means of preventing
heart attacks as well as treatment for existing heart disease. Adver-
tisements in medical journals and lay journals more than merely intimate
that certain margarines and oils will reduce the incidence of CHD and
heart attacks. These ads almost imply negligence on the part of the
practicing physician who does not order his patient to alter his diet to
conform to a rigid, strictly heart-conscious, increased polyunsaturated
fat food intake (Pinckney, 1971), Pinckney (1971), cites a recent adver-
tisement in the Journal of the American Medical Association that directs
the physician specifically to the fact that he can prevent, and even treat,
coronary heart disease by lowering his patient's cholesterol through the
use of polyunsaturates. A margarine ad showing a photo of a preteenager
is headlined: "Is there a heart attack in his future?" Two recent family
magazines contained an ad stating "many doctors advise everyone in your
family to start eating foods that help lower cholesterol levels" (Good
Housekeeping 173(6):145; Redbook 138(2):151).
This type of heavily biased information constantly before the public
indirectly intimates that consuming natural animal food products will
actively invite the occurrence of heart disease. Eggs have probably
attracted more criticism than other animal products because they undoubtedly
do contain more cholesterol than any other natural food source. Two eggs
(approximately 100 grams of edible egg) may contain 460 to 940 mg. of
cholesterol (Turk and Barnett, 1971) depending upon the type of hens,
their egg production (Bartov et al., 1971) and method used for the deter-
mination (Weiss et al., 1964). Other animal products may contain the
following approximate mg. of cholesterol per 100 gms.: beef, 125; beef
liver, 320; pork loin or chop, 70-105; turkey dark meat, 16-26; chicken
fryer, 60-90; butter, 20; and cheddar cheese, 32 (PENB bulletin).
It is possible that researchers may be able to reduce the composition
of their respective products, in regard to cholesterol, through nutritional
or genetic alterations. Clarenburg et al. (1971) has already reported
feeding a plant sterol (sitosterol) at the two percent level in the diet
of laying hens which resulted in a 35 percent reduction in egg cholesterol
and addition of the plant sterol to the composition of the yolk (sitosterol
interferes with intestinal absorption of cholesterol; thus, it lowers cho-
lesterol levels by promoting fecal excretion of sterols and their degrada-
tion products). Changes such as these would undoubtedly be a tremendous
expense to the industry, and would ultimately be passed on to the consumer.
Additionally, in the light of current research now available in the litera-
ture, there may be needless concern about animal food products that contain
high levels of cholesterol. It is perhaps time also, for those in the
agricultural product areas to change from a defensive position to that of
the offense in regard to the much publicized criticism of their cholesterol
containing products. Informed products people can now do more than cringe
when "cholesterol" is mentioned because sufficient research is now avail-
able concerning atherosclerosis to suggest that opponents of cholesterol
and cholesterol containing foods should re-evaluate their position.
FAI.I.ACIES OF POLYUNSATUPATED ADVERTISING
The most detrimental effects of cholesterol commercialism may be the
neutralizing impact on newer, more recent research findings that would
elucidate the factors that do influence heart disease. Important factors
that are generally unknown by the public include some of the following
There have been some indications that a diet containing a slightly
increased amount of polyunsaturates does lower laboratory-measured serum
cholesterol (although this effect does not seem to persist). Most impor-
tant, however, is the fact that there is still no clinical evidence that
a diet-lowered serum cholesterol in any way prevents, or modifies heart
attacks or heart disease (Pinckney, 1971). Also, during the years 1950
through 1967, the incidence of CHD increased sharply from less than 220
deaths per 100,000 in 1950 to approximately 390 deaths per 100,000 in
1967. Within this same period, egg consumption on a per capital basis
declined from approximately 390 eggs in 1950 to a 1967, and present, low
of approximately 320 eggs per capital (Pope, 1971a).
A similar report by the World Health Organization (1970) noted an
increase in mortality from atherosclerotic heart disease despite attempts
to control heart patients' serum cholesterol by way of dietary changes -
usually increases in polyunsaturates and occasionally decreased cholesterol
intake. In contrast, Japan, whose consumption of dairy products, eggs and
saturated fat foods has greatly increased since 1955, showed a 14 percent
decrease in heart attack deaths for the same time period.
The Framingham diet study (1971) completed in Framingham, Massachusetts,
over a ten-year period with hundreds of people, concluded that diet had no
effect on the incidence of coronary heart disease.
Serum cholesterol levels reportedly decrease approximately three mgs.
for each 100 mgs. of cholesterol that are removed from the diet (Pinckney,
1971). Thus, if one follows the American Heart Association guidelines,
which recommend increased polyunsaturates and decreased intake of choles-
terol by 300 mg., the serum cholesterol would be reduced by only approxi-
mately ten mg.
One of the most important facts seemingly overlooked by the FDA,
advertisers of polyunsaturates and many physicians, is the fact that
heating of polyunsaturates tends to resaturate the product. Resaturation
is possible at temperatures and times commonly used in cooking and thus
defeats the very purpose for which polyunsaturates are commercially pro-
moted. There are many references available that report a decreased
iodine number (increased saturation) when unsaturated fats are heated
(Poling et al., 1962; Arffman, 1969; Kilgore and Bailey, 1970; Stasch
and Kilgore, 1963). The degree of unsaturation becomes even worse if the
fat or oil is reused as it sometimes is by the housewife and is nearly
always so in restaurants and other food service establishments. There is
even some evidence of increased atherosclerosis, tumors, poor growth and
death in test animals fed diets containing heated polyunsaturated fats
(Kummerow, 1961; Nutrition Reviews, 1957); a similar report of increased
atherosclerotic events has occurred with men on an experimentally high
polyunsaturated fat diet (Pearce and Dayton, 1970).
Ingestion of greater amounts of polynsaturated foods and restriction
of cholesterol containing foods, such as eggs, in hopes of preventing or
even treating CHD appears to be a false assumption.
FACTORS THAT MAY ATTRIBUTE TO CORONARY HEART DISEASE
Important research findings which may be overlooked because of the
cholesterol issue,include several reports that have implicated heredity,
age, sex, lack of exercise, overweight, and excessive cigarette smoking
(Burton, 1965; Krause, 1968). There are also recent reports that indicate
a relationship of hardness of water to heart disease (Bolchum, 1971), the
serum cholesterol levels in relation to blood type (Oliver, 1969) and a
relationship of carbon monoxide to atherosclerosis (National Institutes
of Health, 1970).
Although much evidence indicates diet is not the major cause of
heart disease, several recent reports (Nutrition Today, 1970; Internal
Medicine and Diagnosis News, 1970; Agricultural Research, 1971) have
indicated sucrose as a source of atherosclerosis and CHD. One basis for
this theory is the prevalence for atherosclerosis in highly developed
countries, with the largest dietary differences between the poor and the
prosperous countries being sugar consumption. In the last 70 years sugar
has doubled in the United States, whereas fat consumption has increased
only 12 percent.
Friedman (1958, 1964, 1969a, 1969b) has reported the importance of
stress on blood levels of cholesterol (neurogenic hypercholesteremia),
which suggest that laboratory-measured serum cholesterol levels may be an
invalid indicator.of heart disease. Acute rises in laboratory-measured
serum cholesterol have occurred In tax accountants at the height of tax
season, in students during examinations, and in military personnel under-
going stress, all with absolutely no change in diet. Other studies which
have received equally minimal attention, include the significant relation-
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ships that exist between heart disease and job stress and risk factors
(French and Caplan, 1970).
The much publicized association of cholesterol to atherosclerosis
has made it difficult for the consumer to accept the conclusions of up-
dated research concerning heart disease; in essence this conclusion is
that no single cause can be clearly associated with atherosclerosis. How-
ever, there is substantial evidence to refute the theory that cholesterol
contained in the diet will cause CHD. It is also indicated that substitu-
tion of polyunsaturates for cholesterol containing animal products will
not effectively alter serum cholesterol levels or combat heart disease.
The current information indicates it would be unwise to severely alter
one's diet (except under doctor's orders) with substitutes when natural
products such as milk, meat and eggs are available that contain high
amounts of protein, vitamins, minerals and even cholesterol. The Nutrition
Council of the American Medical Association does not support the American
Heart Association in its critical opinion of eggs (Pope, 1971b). The Food
and Nutrition Board, National Academy of Sciences and National Research
Council also make the following statements: "In spite of the large amount
of information accumulated in recent years about atherosclerosis and its
pathogenesis, many gaps in knowledge remain. Results of recent studies
while valuable and though provoking do not provide sufficient data for
firm dietary recommendations for radical dietary changes. Until we learn
more about which fats are desirable nutritionally, the board recommends
that the consumer should partake of the foods that make up a varied
adequate and not overly-rich diet and maintain a normal body weight by
judicious control of calorie intake and by daily exercise" (Hursh, 1970).
Agricultural Research, August, 1971. The Carbohydrate Question, p. 3
U. S. Department of Agriculture.
Arffman, E., 1960. Heated fats and allied compounds as carcinogens: A
critical review of experimental results. J. Nat. Cancer Institute
Bartov, I., S. Bornstein and P. Budowski, 1971. Variability of cholesterol
concentration in plasma and egg yolks of hens and evaluation of the
effect of some dietary oils. Poultry Sci. 50:1357.
Bolchum, 0. J., J. S. O'Brien and B. D. Goldstein, 1971. Ozone and
unsaturated fatty acids. Arch. of Environmental Health, 22:32.
Burton, B. T., 1965. The Heinz Handbook of Nutrition. Second Edition,
p. 68. Blakiston Division McGraw-Hill Book Co., New York.
Clarenburg, R. A., Kim Chung and C. M. Wakefield, 1971. Reducing the
egg cholesterol level by including emulsified sitosterol in standard
chicken diets. J. Nutr. 101:289.
Framingham Diet Study, 1971. U. S. Public Health Service.
French, J. R. P., and R. D. Caplan, 1970. Psychosocial factors in
coronary heart disease. Industrial Medicine (September).
Friedman, M., R. H. Rosenman and V. Carroll, 1958. Changes in the serum
cholesterol and blood clotting time in men subject to cylic variation
of occupational stress. Circulation, 17:852 (May).
Friedman, M., R. H. Rosenman and S. Byers, 1964. Serum lipids and con-
junctival circulation after fat ingestion in men exhibiting type-A
behavior pattern. Circulation, 29:874 (June).
Friedman, M., S. R. Flek and S. 0. Byers, 1969a. Abolition of milieu-
induced hyperlipemia in the rat by electrolytic lesion in the
anterior hypothalamus. Proc. Soc. Exp. Biol. Med. 131:288 (May).
Friedman, M., S. 0. Byers and S. R. Flek, 1969b. The induction of
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Hursh, L. M., 1970. What's all this fuss about cholesterol. Poultry
Tribune, p. 52 (April).
Internal Medicine and Diagnosis News, 1970. Serum Triglycerides Fall,
Kilgore, L., and M. Bailey, 1970. Degradation of linoleic acid during
potato frying. J. Am. Dietetic Assn. 56:130 (February).
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pp. 47-48. W. B. Saunders Co., Philadelphia.
Kummerow, F. A., 1961. Lipids and their oxidation. A Symposium on Foods
edited by Schultz, H. W. Oregon State University.
National Institutes of Health, 1970. Dietary Management of Hyperlipipro-
teinemia. Bethesda, Maryland.
Nutrition Reviews, 1957. Nature of the toxic substances in overheated
oils. Volume 15:346 (September).
Nutrition Today, 1970. More about sucrose and atherosclerosis, Autumn,
Oliver, M. F., R. D. Cumming, H. Geizerova and J. D. Heady, 1969. Serum
cholesterol and ABO and rhesus blood types. Lancet, 2:605.
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raise some interesting questions. J. Am. Med. Assoc. 214:2264
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cholesterol. Medical Counterpoint, 3(5) (May).
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of temperature, heating time and aeration upon the nutritive value of
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