Choline (Vitamin B4)
It belongs to the vitamin-like compounds of the water-soluble B group. It is part of the phospholipids that build cell membranes, it is necessary for the production of acetylcholine (a key neurotransmitter) and it acts as a lipotropic factor — managing the export of fats from the liver (VLDL assembly) and preventing its fatty degeneration [1] [5]. The body can synthesize small amounts of it on its own in the liver, using methyl group donors (including methionine). The NRC requirement (RA) is about 425 mg/1000 kcal ME for an adult dog and about 637 mg for an adult cat [1].
Where it's found: Brewer's yeast, egg yolks, brain, liver, heart and — to a lesser extent — muscle meat.
Deficiency: It can occur during a period of intensive growth or in older animals. It results in fatty liver, neurological disturbances (in seniors, dementia-like symptoms) and slowed growth [5]. In the cat choline is of particular importance with the risk of hepatic lipidosis [3].
Excess: From natural food practically impossible — the excess is efficiently excreted. With an extreme overdose of synthetic supplements, overstimulation of the nervous system may occur (drooling, vomiting, diarrhea, drop in blood pressure) [4].
Connection with methionine
Part of the choline requirement is covered by the body synthesizing it from the methyl groups supplied by methionine. A diet low in choline and at the same time low in sulfur amino acids doubly burdens the liver — which is why both components are worth considering together.
Sources
- National Research Council (2006). Nutrient Requirements of Dogs and Cats. National Academies Press. https://nap.nationalacademies.org/catalog/10668/nutrient-requirements-of-dogs-and-cats
- Beynen AC (2021). Choline in dog food. Bonny Canteen 2:129-140. https://www.researchgate.net/publication/351624362_Beynen_AC_2021_Choline_in_dog_food
- Biourge VC et al. (1991). Dietary management of idiopathic feline hepatic lipidosis with a liquid diet supplemented with citrulline and choline. https://pubmed.ncbi.nlm.nih.gov/1941213/
- Merck Veterinary Manual (2023). Nutritional Requirements of Small Animals. https://www.merckvetmanual.com/management-and-nutrition/nutrition-small-animals/nutritional-requirements-of-small-animals
- Hand MS, Thatcher CD, Remillard RL, Roudebush P, Novotny BJ (2010). Small Animal Clinical Nutrition, 5th Edition. https://www.markmorrisinstitute.org/sacn5.html