Considerations:
Race and Disease
The complexity of the interplay of factors that influence
the expression of disease in various individuals and between groups of people
adequately reflects and illustrates the complexity of the factors affecting
intelligence. Some of these factors include: environmental pressures, genetics,
biochemistry, emotional states, and socioeconomic conditions.
I.
The implications of cholesterol in heart disease are some of the most pressing health issues of today, but typically are
not well understood by the general public. While most people have heard of
the importance of maintaining a “low cholesterol level” to prevent
heart disease, the majority do not fully realize the importance of cholesterol
in the proper functioning of the human body or its direct role in heart disease.
Cholesterol is needed in the body for cell membrane synthesis, as a component
of certain body tissues, and as a precursor to the production of certain steroid
hormones and vitamin D.
Cholesterol cannot dissolve in the blood stream and must be transported
by specific carriers, within the blood, to the body’s cells,. The major
carrier are low-density lipoprotein (LDL), which consist of plasma particles
of cholesterol molecules and other lipids bound to proteins. Another cholesterol
carrier is high-density lipoprotein (HDL), which is found in much lower concentration
than LDL. When too much LDL accumulates in the blood (as can occur with hypercholesterolemia,
in which cell membranes have faulty LDL receptors), it can build up on the
inside walls of the arteries, occasionally hardening into plaque. This narrowing
of the arteries can lead to a clogged artery if a thrombus is caught in the
plaque, and thus stop the flow of blood. HDL, however, is thought to carry
the cholesterol from the blood stream to the liver, where it will be passed
from the body. HDL may also remove the excess cholesterol from arterial plaque.
A high LDL level is not healthy, while a high HDL level is
healthy. The ratio of LDL to HDL is the best indicator of cardiovascular disease
susceptibility (1).
II. There are multiple factors that affect the
ratios of HDL and LDL. For instance,
exercise increases HDL concentration, while smoking decreases it. A person’s
genetics and race have now joined the forefront of factors that are considered
when evaluating health risks associated with cholesterol. Some studies have
shown that obese black Americans (regardless of gender) typically have higher
HDL levels than obese white Americans do, which indicates that blacks have
a “more favorable lipoprotein profile” (2). These that studies
claiming a racial difference may not be adequately thorough, but they are
worthy of consideration and critique. There is likely a significant contribution
of genetic predisposition towards obesity and cholesterol levels, but this
predisposition is not unrelated to or unaffected by environment.
Perhaps more important that the genes that parents pass on to their children
are the lifestyle habits that
the children assume. Obesity, hypertension, and cholesterol levels are influenced
by diet (primarily by dietary fat and salt intake), exercise, smoking and
alcohol consumption, and also genetic predisposition. These factors have not
always be taken completely into consideration when studying the manifestations
of various diseases between racial groups. Hypertension is an example of a
disease that has been associated with African origins. Klag, et al., demonstrated
that a higher incidence of hypertension among African Americans was only evident
in groups who with low socioeconomic status (3). This is a disease for which
African Americans supposedly have a higher predisposition (though various
studies yield conflicting results (4)), yet Klag, et al., have suggested that
it may take a negative, stressful environment to bring about the expression
of this trait. Thus, the origin of the sample of people in a given study has
a significant effect on the results, for lifestyle greatly impacts ones health.
These factors complicate the validity of studies claiming a purely genetic
origin for the differences in cholesterol, hypertension, and obesity between
groups of different skin colors. At the same time,
it is imperative that the biology not be ignored.
III. Should a difference indeed exist between cholesterol
levels in various races, information
about this difference might be further obtained through comparisons of the
mechanisms behind cholesterol accumulation within and between
racial groups. This would potentially yield further insight into the role
of cholesterol in the body; for instance, whether high LDL levels are somehow
beneficial to humans under certain environmental conditions. If high levels
of cholesterol assist the body in vitamin D production, perhaps it would be
advantageous for groups of people who evolved in high latitudes (where the
intensity of the sun’s rays is diminished) to have excess cholesterol.
More insight might be gained about the function of the heart, as well, such
as how cholesterol accumulation effects blood flow and the physical effort
of the heart.
Researchers may also learn more about the role of genes in the POMC-derived hormones and in cholesterol processing;
for example, which genes code for LDL, HDL, and cell-surface receptor protein
production, how these genes function, and how the environment influences the
expression of these genes. Researchers would also hopefully understand more
about the evolution of physiological differences between groups of humans,
again relating to how the environment in which various groups evolved influenced
their biology. In order for studies such as these to yield worthwhile results,
they would have to be performed on people from various racial classifications.
Doctors and researchers must be wary of unconscious discrimination or unethical
testing standards of one racial group over another.
IV.
If verifiable differences in diseases between “racial groups”
are determined, significant implications for the health care of individuals
will arise. There is the ubiquitous
risk of discrimination on the basis of health profiles. Insurance companies
or employers may hesitate to provide service or hire an individual on the
basis of race of skin color if his/her ethnic group is associated with a greater
risk of a particular disease. Treatment approaches may also vary depending
on the race of an individual. Genetic screening will likely increase as correlations
are made between genetic predisposition and physiological manifestation. This
will be beneficial in identifying patients who are at-risk for certain diseases
and in implementing preventative measures; yet it could also potentially lead
to superficial examination or inadequate treatment of those people whose “race”
does not correspond with a “genetic predisposition” for certain
health problems. This would also constitute a form of discrimination, whether
intentional or inadvertent, and measures must be taken to avoid it.
References and Suggested Readings
(1) Campbell, Neil A. Biology,
4th Edition. Menlo Park, CA: The Benjamin/Cummings Publishing
Company, Inc., 1996.
(2) Després, Jean-Pierre; et al. “Race,
Visceral Adipose Tissue, Plasma Lipids, and Lipoprotein Lipase Activity in
Men and Women: The Health, Risk Factors, Exercise Training, and Genetis (HERITAGE)
Family Study.” Ateriosclerosis, Thrombosis, and Vascular Biology.
August 2000. pp. 1932-1935.
(3) Klag, Michael J.; et al. “The Association
of Skin Color With Blood Pressure in US Blacks With Low Socioeconomic Status.”
Journal of American Medical Association. February 1991. Vol 265 (5),
pp. 559-602.
(4) Keil, J. E.; et al. “Skin Color and Mortality.”
American Journal of Epidemiology. December 1992. Vol 136 (11), pp.
1295-1302.
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