Kefir for children: Is it safe, and when can you offer it?

What is kefir, and how is it different from yoghurt?

Kefir is a fermented milk drink that originated in the Caucasus. It is made by adding kefir grains to milk. These grains are a mass of polysaccharides and proteins that host lactic acid bacteria, acetic acid bacteria and yeasts.

Yoghurt is made using just two bacteria, Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus. Its fermentation is solely lactic: it does not produce alcohol and gives yoghurt its clean, tangy flavour.

In traditional kefir, yeasts add a second fermentation. They consume some of the milk sugar and produce gas and alcohol; a review of kefir studies reported levels of 0.5% to 2% by volume [2].

There is another difference. Live yoghurt cultures help people who have difficulty digesting lactose, and the European Food Safety Authority recognises this [3]. Kefir does not have this authorised health claim in the European Union.

Why isn’t homemade kefir suitable for children?

Because of the alcohol. There is no safe amount of alcohol for health (WHO): the less, the better, and none during pregnancy, breastfeeding or childhood, before driving, or when your medication does not allow it. With homemade kefir, there is no way to know how much it contains.

In the first years of life, the liver is less able to metabolise alcohol than an adult’s. An amount that has no noticeable effect on you may have a much greater effect on a young child.

You cannot measure it at home without laboratory equipment. The amount depends on how it ferments [2]. Kitchen temperature, the ratio of grains to milk and fermentation time can all change the amount from one batch to another.

In addition, kefir grains shared between individuals are not subject to hygiene checks and may carry moulds or pathogenic bacteria.

At what age can a child have kefir?

From 12 months, and always commercial, plain and unsweetened. This is the cautious approach we take in consultations, because paediatric guidelines do not set a specific age for kefir.

For the first six months, babies are fed only breast milk or, when that is not available, infant formula. Between six and twelve months, complementary feeding begins, while milk remains the main food.

Cow’s milk should not be the main drink before 12 months, although small amounts can be added to meals [4]. Plain yoghurt and fresh cheese can be offered in small amounts from 9 or 10 months, according to the Spanish Association of Paediatrics [1].

From twelve months, plain commercial kefir can be included as one of a child’s dairy foods, in amounts similar to yoghurt. Homemade kefir should be avoided throughout childhood because its alcohol content varies from batch to batch [2].

How to offer it for the first time

Start with a few spoonfuls at breakfast or as a snack, on its own or mixed with ripe fruit. Offer it with a spoon or in an open cup, like other dairy foods.

It tastes more sour than yoghurt and is slightly fizzy, so it is normal for a child to reject it at first. Offer it again on another day without pressuring them. Many children need to try a new flavour several times before accepting it.

Count it as one of the day’s dairy servings: up to 3 servings, preferably plain and unsweetened. If your child has already had yoghurt, cheese and milk that day, kefir can wait until tomorrow.

Does kefir have probiotic benefits for children?

You often hear that kefir boosts immunity, prevents colds or settles the stomach. The evidence is much more limited.

The effects of a probiotic depend on the specific strain and dose tested in trials with children. For this reason, the European paediatric gastroenterology society advises against using probiotics without a documented benefit [5]. The fact that a fermented food contains live bacteria is not enough to attribute health effects to it.

For kefir, almost all studies have been conducted in laboratories or in adults, and very few involve children. At present, there is no high-quality evidence to support using it to treat colic or diarrhoea, or to prevent infections in children [5]. It can be part of their diet as another dairy food, without expecting it to act as a remedy.

How to choose kefir at the supermarket

Many products are not suitable for a young child. Check three things on the label.

A short ingredient list. Pasteurised cow’s, goat’s or sheep’s milk and lactic ferments or kefir cultures, and nothing else. Commercial kefir is made with selected cultures under controlled conditions, but the label does not state its alcohol content. Choose plain kefir from established food brands rather than artisan fermented drinks.

No sugar or sweeteners. The Spanish Association of Paediatrics advises avoiding added sugars in the early years so children do not become accustomed to very sweet flavours [1]. Many fruit-flavoured or drinkable kefirs contain them. If you see sugar, dextrose, syrup, honey or concentrated juice in the ingredients, leave it on the shelf.

Whole milk. Unless your paediatrician advises otherwise, dairy foods in early childhood should be full-fat. Milk fat provides energy and contains vitamins A and D.

If your child has an allergy or finds milk hard to digest

If your child finds milk hard to digest, plain yoghurt is often better tolerated because its live cultures help digest lactose [3]. It may be useful if lactose intolerance is suspected; a doctor should confirm this. Yoghurt can also be offered with a spoon or during baby-led weaning.

With a suspected or confirmed cow’s milk protein allergy, neither kefir nor yoghurt is suitable. Goat’s and sheep’s milk products are not suitable either, because their proteins are very similar. They should be replaced with formula or the plan recommended by your paediatrician or allergist.

What mistakes do we see in consultations?

These are situations we see often, including in families who take great care over what their children eat.

• Giving homemade kefir because it is natural, without knowing how much alcohol that batch contains.
• Buying fruit kefir thinking it is the same as plain kefir, when it contains added sugar.
• Offering it as a remedy for diarrhoea or colds, which kefir has not been shown to treat.
• Filling a child’s day with dairy foods before age one, leaving less room for iron-rich foods.