My first Publication CC April Edition-19-High Resolution | Page 40

Pet Nutrition
Yeast in petfood
Dr A C Beynen
was professor of
veterinary nutrition
at the Faculty
of Veterinary
Medicine, Utrecht
University, Th e
Netherlands in the
period of 1993-2007.
40
Many dog and cat foods declare a yeast ingredient, most
commonly brewer’s dried yeast, but also yeast extract, yeast
cell walls, selenium yeast or yeast culture. Brewer’s yeast is
a by-product from the brewing of beer or ale. Extracts and
cell walls are yeast parts. Selenium yeast is grown in nutrient
mixtures enriched with the trace element. Yeast culture is yeast
and its growth medium.
Until the 1950s, whole dried yeast served as source of
B-vitamins in experimental dog foods with highly purifi ed
ingredients. By using that kind of foods, black-tongue disease
in dogs was found to respond to consumption of brewer’s
yeast (1), which led to the identifi cation of vitamin B3. Yeast
is lauded as B-vitamin powerhouse, but is as such needless
for current petfoods that are effectively and profi tably
supplemented with pure B vitamins. Similar reasoning holds
for selenium yeast (2).
Brewer’s yeast in petfood is rarely linked to health claims.
Nutritional yeast supplements may promise fl ea control,
healthy skin and coat, but do so without evidence. About 1%
of brewer’s yeast is often added to dry food for palatability,
which requires securing for each application. MOS (mannan-
oligosaccharides) from yeast cell walls is touted for gut and
immune health, but dog studies are unsupportive (3). Purifi ed
yeast beta-glucans can stimulate immune responses, albeit
without known impact on pets’ health maintenance (4).
Yeasts constitute a wide variety of single-celled organisms.
Many are safe and useful such as the species employed in
baking and production of beverage and fuel alcohol. Moderate
yeast amounts in petfood seem harmless to dogs and cats.
Curiously, one petfood brand carries “no added yeast”
as label claim (5). As specifi c yeast species can cause skin
infections in dogs, anti-yeast foods are being proposed, but
their effi cacy is unsubstantiated.
Creature Companion | April 2019 • Vol. XII • Issue 4 • Noida