Common antioxidants include ascorbic acid (vitamin C) and
vitamin E. Mountains of research suggest dietary antioxidants
have health benefits for pets.
Oxidative stress is an important cause of many pet diseases.
Hence, the petfood industry's strong interest in antioxidants.
Petfood researchers have intensely studied these so-called
"elixirs of health" and their role in promoting health.
Mountains of research suggest dietary antioxidants have
health benefits for pets and people. Conversely, some large
clinical trials with antioxidant supplements did not detect
benefits with the formulations tested.
Do not annihilate
The following reports focus on dietary antioxidant health
benefits for pets. However, when considering antioxidants, it
should be remembered that more is not necessarily better.
Oxidative stress is involved in the pathogenesis of many
diseases, but its complete annihilation may lead to negative
clinical effects in our pets. In other words, excess
supplementation may be harmful (see "Antioxidants: can they be
Inflammatory bowel disease
Khoo showed that higher levels of dietary antioxidants or
nutrients such as fish oil may be indicated for decreasing
inflammation in cats (C. Khoo,
., 2007). He studied the effect of antioxidants on immune and
inflammatory parameters in cats with inflammatory bowel disease
Ten healthy and 10 IBD cats were fed wet food with low
antioxidants (Ctrl) and test food (Aox) with added vitamin E,
vitamin C and beta carotene for four weeks each in a randomized
cross-over design. Both foods were completely balanced for
adult cats. Serum vitamins E and C, DNA damage (comet assay),
lymphocyte subsets and proliferation were measured at weeks
four and eight.
Results showed that serum vitamins E and C were
significantly increased in healthy and IBD cats on the Aox vs.
Ctrl food. The Aox food tended to reduce the lymphocyte
proliferation activity in both groups of cats. Results showed
that IBD cats have a dysregulated and hyper-inflammatory immune
response compared to healthy cats.
Milgram's work suggests that long-term maintenance on
alpha-lipoic acid (LA) and acetyl-L-carnitine (ALC) help
improve memory in older dogs (N.W. Milgram, 2007). These
antioxidants apparently attenuate age-associated cognitive
decline by slowing the rate of mitochondrial decay and cellular
Beagle dogs between 7.6 and 8.8 years of age administered a
twice daily supplement of LA and ALC over two months made
significantly fewer errors in reaching the learning criterion
on two landmark discrimination tasks compared to controls
administered a methylcellulose placebo.
The improved performance on the landmark task of dogs
supplemented with LA and ALC provides evidence of the
effectiveness of this supplement in improving discrimination
and allocentric spatial learning.
Park demonstrated that the dietary antioxidant bixin
heightened cell-mediated and humoral immune response in cats
., 2007). Specifically, it inhibited DNA oxidative damage and
inflammation in cats.
Bixin is an antioxidant compound extracted from the annatto
seed. Female domestic cats were fed bixin daily for 16 weeks.
Blood was sampled in weeks zero, six, 12 and 16. All cats were
then vaccinated with an attenuated polyvalent vaccine in weeks
12 and 14. Skin hypersensitivity response (DTH) to saline,
concanavalin A, the vaccine and histamine was assessed in weeks
12 and 16.
Cats fed 5 mg bixin generally showed the highest immune
stimulatory and antioxidative action. In this treatment, bixin
enhanced lymphoblastogenic response, populations of T helper
and T cytotoxic cells, NK cytotoxicity and IgG production.
Bixin also inhibited DNA damage. At 10 mg, bixin stimulated
DTH response to con A, percent of total T and T cytotoxic
cells, and IgG production; however, it inhibited
mitogen-induced lymphocyte proliferation. All doses of bixin
reduced skin response to histamine and CD18 subpopulations.
The evidence for supplementing petfoods for health benefits
is good but mixed. Research focused on dogs and cats is really
just in its infancy. It's a highly complex field that will
continue to impact petfood formulation.
Pets (and people) have evolved and adapted to
symbiotically live with persistent, low-grade, oxidative
stress. To some extent, this oxidative stress may actually
benefit the physiological functioning of cells. Thus, using
antioxidants to reduce oxidative stress to levels below
some physiological threshold may trigger intracellular
signaling pathways that damage cellular machinery.
Laviano contends this should be a critical area for
future investigations (Laviano, 2007). He complains about
the "media-driven assumption that oxidative stress is
always harmful and antioxidant supplements are nearly
always beneficial." He points out that when considering
antioxidant therapy, more is not necessarily better.
What do you think?
Stand up for your opinion
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