Safegaurding Your Pets Against Air Pollution Vol XII , Issue No 12 , Dec 2019 | Seite 40

Pet Nutrition
Carotenoids in petfood
Carotenoids pertain to pigments synthesized by plants. They
participate in capturing sunlight energy and furnish the variety
of yellow to red colors in fruits and vegetables. Highlighted
carotenoids in petfood are mostly linked with immunity support
and high antioxidant value. The four health carotenoids concern
beta-carotene, lycopene, lutein and astaxanthin. Prototypical
ingredients, rather than concentrated additives, serve as
carotenoid carriers.
Dr A C Beynen
was professor of
Veterinary Nutrition
at the Faculty of
Veterinary Medicine,
Utrecht University,
The Netherlands
in the period of
1993-2007.
Beta-carotene is named after carrots and provides their yellowish-
orange color. The intestinal wall of dogs takes up beta-carotene and
can convert it into vitamin A. In contrast, cats require preformed
vitamin A as they cannot synthesize it. “Carrots as natural source
of beta-carotene” is a phrase used in some petfood promotional
texts. Immune-health claims for dietary beta-carotene are not
substantiated by published research in dogs and cats.
Lycopene is responsible for the red color in tomatoes, lutein is
so for the yellow-colored marigold fl owers and astaxanthin for
the red of krill shells and specifi c microalgae. Those natural
sources function as carotenoid delivery vehicles in petfood. After
feeding purifi ed forms of lutein and astaxanthin to dogs and cats,
indicators of the animals’ immune responses were measured. The
results do not provide solid evidence that lutein and astaxanthin
enhance immunity. Data on lycopene are lacking.
Antioxidants may neutralize unstable, reactive molecules
(free radicals) and prevent them from doing damage to various
chemical, bodily structures. There is no proof that the four
carotenoids have antioxidant activity within the canine and
feline body. And furthermore, it has not been demonstrated that
added carotenoids in complete petfood improve immune and
visible health of dogs and cats.
CAROTENOID STRUCTURES
Plant carotenoids are located in
chloro- and chromoplasts. They give
colors to non-green (parts of) plants,
while being masked by the presence
of green chlorophyll. Lycopene and
ß-carotene are ranked among the
carotenes. Lutein and astaxanthin
belong to the oxycarotenoids/
xanthophylls.
All-trans lycopene (C40H56) is a
linear tetraterpene assembled from
8 isoprene units. ß-Carotene is
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Creature Companion | December 2019 • Vol. XII • Issue 12 • Noida
formed by enzymatic conversion of
lycopene’s ends into six-carbon rings.
Lutein results from end cyclization of
lycopene and hydroxylation of each
ring. Astaxanthin’s rings have both a
keto and hydroxyl group.
CAROTENOID CARRIERS
Carotenoid contents in plant materials
are highly variable as they depend
on many factors, including cultivar,
growing conditions, harvest time and
ripening stage. For the carotenoid