The makers of Marmite said it was "disappointing" a council has decided to impose a ban on the spread at their school breakfast clubs.
Ceredigion Council in Mid Wales has taken the yeast extract product off the menu at their 51 breakfast clubs within the county because of a "high level of salt."
The makers of Marmite responded by saying only a small amount was needed to make "toast tasty" for children.
A council spokesman told BBC News Online: "Breakfast clubs are intended to improve the health and concentration of children - to assist in the raising of standards of learning and attainment.
"But anything served must be healthy and nutritionally balanced.
"Marmite is not included on the list of items as it does include a high level of salt.
"Low sugar marmalade or jam can be spread on toast, but lemon curd is not on the list of provisions."
The spread has been renowned for dividing opinion about its merits ever since 1902 when the Marmite Food Company (later Marmite Ltd) was set up in Burton on Trent.
On the Marmite website, the health properties of the product are touted: "It's because we add a special vitamin blend to Marmite, enhancing the naturally nutritious yeast that's already there, that you can be sure Marmite's good for you.
"Plus, we think toast with Marmite tastes better than most vitamin pills...
"B vitamins benefit your body in all sorts of ways. They help regulate the kidneys, liver and nervous system as well as assisting with skin disorders and boosting energy..."
A spokesman for Unilever, who make Marmite, said: "It is disappointing the council is not including Marmite in its items for breakfast clubs.
"It does contain salt and it is important that only small quantities are used for taste.
"But it is not harmful, and only a small amount is required to make toast tasty for children."