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Further
readings
Coenzyme Q10 in
health and disease
The literature concerning the importance of coenzyme Q10 in health
and disease has been reviewed. Usual dietary intake together with
normal in vivo synthesis seems to fulfil the demands for Q10 in
healthy individuals. The importance of Q10 supplementation for
general health has not been investigated in controlled experiments.
The literature allows no firm conclusions about the significance of
Q10 in physical activity. In different cardiovascular diseases,
including cardiomyopathy, relatively low levels of Q10 in myocardial
tissue have been reported. Positive clinical and haemodynamic
effects of oral Q10 supplementation have been observed in
double-blind trials, especially in chronic heart failure.
These effects should be further examined. No important adverse
effects have been reported from experiments using daily supplements
of up to 200 mg Q10 for 6-12 months and 100 mg daily for up to 6 y.
Eur J Clin Nutr 1999 Oct;53(10):764-70
Overvad K et al.; The Danish Nutrition Council, Soborg, Denmark
Toward a new
definition of essential nutrients: is it now time for a third 'vitamin'
paradigm?
The concepts of vitamin 'deficiency'
diseases and the recommended dietary allowances (RDAs) have not kept
pace with the growing understanding of the cellular and molecular
functions of vitamins and other micronutrients. As a consequence,
many researchers and clinicians rely on outdated signs and symptoms
in assessing nutritional deficiencies.
A new paradigm, presented here, proposes that:
-
deficiencies can be identified on
biochemical and molecular levels long before they become
clinically visible;
-
the definition of essential
micronutrients be broadened to include some carotenoids and
flavonoids, as well as various human metabolites, such as
coenzyme Q10, carnitine, and alpha-lipoic acid, which are also
dietary constituents;
-
individual nutritional
requirements are partly fixed by genetics but also dynamically
influenced by variations in the body's biochemical milieu and
external stresses;
-
the distinction between
nutritional and pharmacological doses of vitamins is meaningless,
since high doses of micronutrients may be required to achieve
normal metabolic processes in some people.
Med Hypotheses 1999 May;52(5):417-22
Challem JJ; Aloha, Oregon 97006, USA.
Oxidative stress
and Alzheimer disease
Research in the field of molecular biology has helped to provide a
better understanding of oth the cascade of biochemical events that
occurs with Alzheimer disease (AD) and the heterogeneous nature of
the disease. One hypothesis that accounts for both the heterogeneous
nature of AD and the fact that aging is the most obvious risk factor
is that free radicals are involved. The probability of this
involvement is supported by the fact that neurons are extremely
sensitive to attacks by destructive free radicals. Furthermore,
lesions are present in the brains of AD patients that are typically
associated with attacks by free radicals (eg, damage to DNA, protein
oxidation, lipid peroxidation, and advanced glycosylation end
products), and metals (eg, iron, copper, zinc, and aluminum) are
present that have catalytic activity that produce free radicals.
Beta-Amyloid is aggregated and produces more free radicals in the
presence of free radicals; beta-amyloid toxicity is eliminated by
free radical scavengers.
Apolipoprotein E is subject to attacks by free radicals, and
apolipoprotein E peroxidation has been correlated with AD. In
contrast, apolipoprotein E can act as a free radical scavenger and
this behavior is isoform dependent. AD has been linked to
mitochondrial anomalies affecting cytochrome-c oxidase, and these
anomalies may contribute to the abnormal production of free radicals.
Finally, many free radical scavengers (eg, vitamin E, selegeline,
and Ginkgo biloba extract EGb 761) have produced promising results
in relation to AD, as has desferrioxamine-an iron-chelating
agent-and antiinflammatory drugs and estrogens, which also have an
antioxidant effect.
Am J Clin Nutr 2000 Feb;71(2):621S-629S
Christen Y; Fondation Ipsen, 24 rue Erlanger, 75016 Paris, France.
Anti-oxidants as
modulators of immune function.
In order to confirm the hypothesis of the immunomodulating action of
anti-oxidants (bringing back altered immune function to more optimum
values), the possibility that anti-oxidants may be useful in two
experimental models of altered immune function has been studied. The
first is a pathological model, that is, lethal murine endotoxic
shock caused by an LPS injection of 100 mg/kg, in which the
lymphocytes show increased adherence and depressed chemotaxis. The
injection of N-acetylcysteine (150 mg/kg), which increased both
functions in control animals, decreased adherence and increased
chemotaxis in mice with endotoxic shock. The second is a
physiological model; aged human subjects (70 +/- 5-year-old men) who,
in their largest segment of population ('standard' group) showed an
increased lymphocyte adherence and decreased lymphoproliferative
response to mitogens compared with younger adults.
The ingestion of vitamin E (200 mg daily for 3 months in this
standard group) lowered adherence and stimulated lymphoproliferation.
However, a smaller segment of the human population tested showed
'non-standard' values in these lymphocyte functions, that is, very
low adherence and very high proliferation. In those subjects,
vitamin E showed the opposite effects, namely adherence increase and
depressed lymphoproliferation. In both age groups of men, these
functions reached adult levels after vitamin E ingestion. These data
suggest that anti-oxidants preserve adequate function of immune
cells against homeostatic disturbances such as those caused by
endotoxic shock and ageing.
Immunol Cell Biol 2000 Feb;78(1):49-54
Fuente MD, Victor V;Department of Animal Physiology, Faculty of
Biology, Complutense University, Madrid, Spain.
Nutrition and
immunity in the elderly.
Immune function declines with age, leading to increased infection
and cancer rates in aged individuals. In fact, recent progress in
the study of immune ageing has introduced the idea that rather than
a general decline in the functions of the immune system with age,
immune ageing is mainly characterized by a progressive appearance of
immune dysregulation throughout life. Changes appear earlier in life
for cell-mediated immunity than for humoral immunity. Thus,
age-related modifications in cell-mediated immunity, i.e. changes in
naive : memory T-cells, mature : immature T-cells, T-helper 1 :
T-helper 2 cells are more important in the elderly than changes in
humoral immunity, i.e. CD5 : CD5+ cells or length of antibody
responses.
Such evolution of the immune system
has been linked to declining thymus function and to accumulative
antigenic influence over the lifespan. In contrast, innate immunity
(macrophage functions) is preserved or even increased during the
ageing process. This finding shows that the 'primitive' immune
system is less affected by the ageing process than the sophisticated
specific immune system. The present review focuses on innate and
cell-mediated immune changes with ageing. It provides evidence that
primary changes (intrinsic modifications in the immune system) and
secondary changes (resulting from environmental influences during
the lifespan) exert different influences on the immune system.
Primary changes, occurring in healthy individuals, seem less
important nowadays than they were considered to be previously. For
example, interleukin 2 secretion in some very healthy aged
individuals is comparable with that in younger adults.
Primary immune changes may not
explain the increased incidence and severity of infections observed
in the elderly population.Secondary immunological changes are far
more frequent and are certainly responsible for most of the immune
modifications observed in the elderly population. Environmental
factors leading to secondary immune dysfunctions include not only
antigenic influence, which is a reflection of diseases experienced
over the lifespan, but also many other factors such as drug intake,
physical activity and diet; factors for which important changes
occur in the elderly population. Nutritional factors play a major
role in the immune responses of aged individuals and the present
review shows that nutritional influences on immune responses are of
great consequence in aged individuals, even in the very healthy
elderly.
Proc Nutr Soc 1999 Aug;58(3):685-95
Lesourd B, Mazari L; Unite de Medecine Nutritionnelle Geriatrique,
Hopital Charles Foix, Ivry sur Seine, France.
Micronutrients and
ageing: intakes and requirements
Ageing (and related diseases) may be described as a process which
results from impaired immunological, genetic, neurological or
endocrinological functions.
Oxidative mechanisms may play an important role in the ageing
process. It is important, therefore, to emphasize the relationship
between health and nutrition in the elderly, particularly with
regard to antioxidant micronutrient requirements.
Indeed, accelerated ageing may be related to a deficit in the
intakes of antioxidant vitamins (tocopherols, carotenoids and
vitamin C) and trace elements (Zn and Se), as well as to an impaired
adaptative mechanism against oxidative stress.
Physiological modifications occurring during the lifetime and
environmental influences are significant factors contributing to the
impairment of micronutrient status, and these factors have to be
considered when defining the specific requirements of the elderly.
For Fe there is no evidence of benefit of supplementation in healthy
subjects, but in the present state of knowledge combined
supplementation, including Zn, Se, vitamins C and E and carotenoids,
could be the best way to prevent accelerated ageing and reduce the
risk of several common age-related diseases.
Proc Nutr Soc 1999 Aug;58(3):573-8
Richard MJ, Roussel AM;LBSO, Biochimie C, Hopital Albert Michallon,
Grenoble, France.
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