Why are jelly babies used by runners?

At the London Marathon, supporters hold out jelly babies to the runners, and a 2026 report on the race described strangers standing outside pubs with jelly babies and orange slices. The reason is simple: runners on long races are advised to take in carbohydrate, and a jelly baby is an easy way to take some sugar.

Why runners need carbohydrate

Sports scientists recommend taking in carbohydrate during long exercise, and the amount depends on how long the exercise lasts. A 2014 review by the sports scientist Asker Jeukendrup, published in Sports Medicine, set out guidance by duration:

• About an hour. Even a mouth rinse or small amounts of carbohydrate can improve performance. Carbohydrate is detected in the mouth, and this signal has been linked to better performance.
• Two to three hours. A single type of sugar can be used by the body at up to about 60 g an hour, and that is the recommendation for this length of exercise.
• Longer, ultra endurance events. The recommendation rises to about 90 g an hour, but at such high rates the carbohydrate must come from a mix of sugars, such as glucose with fructose, which the gut absorbs through different transporters.

Jelly babies or energy gels?

Energy gels are small sachets of carbohydrate. The sports nutritionist Renee McGregor, writing for the Brighton Half Marathon, says jelly sweets can be used instead of gels and that it is very much down to individual preference. Most gels give 20 to 30 g of carbohydrate, she says, so you would need about five or six jelly babies to match one. She prefers gels herself, because she finds it too hard to chew while running, but has a friend who eats a jelly baby every few minutes.

What is in a jelly baby

A published ingredients list for Bassett's Jelly Babies starts with sugar, glucose syrup and water, followed by gelatine. Sugar, or sucrose, is made of glucose and fructose joined together. Glucose syrup is made by breaking down starch, and the grades used in sweets contain glucose along with maltose and other sugars. So a jelly baby carries more than one kind of sugar: see what is dextrose in sweets?

Things to know

• They contain gelatine. Jelly Babies are not vegetarian: see are Jelly Babies vegetarian?
• They are sugary. Outside a long run, they count towards the sugar you eat each day: see how much sugar is in sweets?
• They stick to teeth. Chewy sweets can cling to teeth: see why do sweets stick to your teeth?
• For people with diabetes, Jelly Babies are sometimes used to treat a hypo, but that is a different matter, and your own care plan comes first: see why are jelly babies used for low blood sugar?

If you are supporting a runner, First Aid for Life's advice for London Marathon spectators is to offer food gently and nothing too large.

We sell Jelly Babies in our pick and mix, by the 100 g.

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