For the Health of It
The Importance of Nutrition in
Enhancing Immunity in the Aging Horse
Reprinted with permission from the July 2013 issue of Equine Disease Quarterly
Over the past century, improvements in health care and advancements in biology, chemistry and medicine have extended the average lifespan of humans and companion animals,
including horses. However, we are now facing new challenges
with the paradox of an older population with increased longevity, while confronted with the potential for many years of poor
health. A better understanding of the mechanisms leading to
a decline in physiologic function with age would provide new
predictive biomarkers and potential therapeutic targets.
It has been well-documented that the aged, including
horses, have increased susceptibility to and prolonged recovery from infectious diseases, poor responses to vaccination,
and increased incidence of various cancers. Furthermore, it
is now accepted that chronic inflammation (inflamm-aging)
is a major underlying condition of many age-related diseases,
such as atherosclerosis, arthritis, cancer, diabetes, osteoporosis,
dementia, vascular diseases, obesity and metabolic syndrome.
In anti-aging research, much attention is focused on nutritional interventions as practical, cost-effective approaches
to mitigating this agerelated breakdown in immune function.
These natural dietary compounds found in a variety of fruits,
vegetables, nuts and seeds are promising candidates in helping
to combat the effects of aging. They possess broad biological
activities: anti-oxidative, anti-inflammatory, detoxification,
regulating signaling pathway, and modulation of enzyme activities (see Table 1).
Since aged horses (>20 years) have increased levels of
inflammation, and treatment with longterm use of non-steroidal anti-inflammatory drugs (NSAIDs) such as flunixin
meglumine and phenylbutazone can pose health problems, we
are interested in nutritional interventions to counteract this
inflamm-aging process.
Flavonoid (quercetin) and polyphenolic compounds (curcuminoids, resveratrol, pterostilbene and hydroxypterostilbene) were compared to phenylbutazone and flunixin meglumine
to determine differences in equine cytokine production in cell
culture. White blood cells from aged horses were isolated and
incubated overnight with each compound or NSAID at multiple concentrations. Inflammation production was measured
when cells were stimulated.
At varying doses (measured in micromolar units [μM]),
each of the compounds and NSAIDs significantly reduced
cellular inflammation: curcuminoids (20 μM), hydroxypterostilbene (40 μM), pterostilbene (80 μM), quercetin (160 μM),
28 • Walking On
Table 1. Natural Dietary Compounds with
Anti-Inflammatory Mechanisms
Group
Compound
Carotenoids
b-carotene, lycopene,
lutein
Flavonoids
quercetin, catechin, epigallocatechin-3-O-gallate,
theaflavin
Isothiocyanates
sulforaphane, phenethyl,
isothiocyanate
Terpenoids
limonene, retinoic acid
Proanthocyanidins
O-3 fatty acids (FA)
eicosapentaenoic acid
(EPA) and docosahexaenoic acid (DHA)
Polyphenolic compounds
curcumin, gingerol, resveratrol, pterostibene
resveratrol (160 μM), flunixin meglumine (40 μM) and
phenylbutazone (>320 μM). Interestingly, curcuminoids at a
concentration of 20 μM reduced inflammation to the same
level as higher doses of flunixin meglumine (40 μM) and phenylbutazone (>320 μM). All natural compounds outperformed
phenylbutazone by being effective at lower doses.
This preliminary research has led into two studies using
aged horses to determine: 1) if a relationship exists between
circulating vitamin and fatty acid levels to systemic inflammation and muscle mass, and 2) if anti-inflammatory supplementation affects immune responses to vaccination. These are
preliminary s ѕ