Consumers are paying up to eight times more for vitamin gummies and sprays despite them often containing fewer nutrients than traditional tablets and capsules, a watchdog has said.

Which? compared the nutrient content, doses, additives and costs across a range of supplements, finding that shoppers are paying “hundreds of pounds more than they need to” by selecting gummy and spray options.

The most expensive gummy Which? assessed was Starpowa Magnesium Super Strength gummies, which cost £1.33 per daily dose while only providing 206mg of magnesium.

The recommended daily intake of magnesium is 375mg, but the supplement was marketed as “high-strength”.

By comparison, Nutriva Magnesium Complex tablets provided 400mg for just 17p per daily dose.

In the case of these two options, shoppers could save £423.40 a year and get a higher dose of magnesium by switching from gummies to tablets, the consumer group said.

It also assessed Holland & Barrett Magnesium Citrate gummies costing 63p per daily dose and providing 150mg of magnesium, while Magnesium Citrate tablets at the same retailer cost 30p per daily dose and provided 300mg magnesium.

Boots Multivitamin gummies cost 15p per daily dose but contained just nine vitamins, none at doses that met daily recommendations, Which? said.

By comparison, Boots A-Z Multivitamin tablets cost 7p per daily dose and contain all 23 nutrients considered by Which? nutrition experts as essential for a multivitamin – most at recommended doses, apart from magnesium and calcium.

The Boots gummies also contained twice as many additives as the tablets, including five different forms of sugar and sweeteners.

Which? also warned that in order to achieve their sweet-like appearance and taste, gummies required additives and fillers including gelling agents, sugars, sweetener, flavouring and stabilisers, all of which took up space that could otherwise be used for active ingredients.

Which? advised consumers to check supplement ingredients to make sure that they provided the required nutrients and doses.

Which? nutritionist Shefalee Loth said: “Gummies and supplement sprays might seem like an appealing alternative to swallowing tablets, but we’ve found that they often contain lower doses of nutrients than traditional supplements, yet come with a much higher price tag.

“Don’t be swayed by colourful packaging, appealing flavours or convenient formats. First, consider whether you actually need a supplement, then compare the nutrients and doses provided, as well as the cost per daily dose, to make sure you’re getting the best value for money.”

A Boots spokeswoman said: “Food supplements are intended to supplement normal nutritional intake and should not be regarded as a substitute for a balanced and varied diet or a healthy lifestyle, as made clear on our product labels.

“Boots is committed to providing customers with wide choice of products catering to different preferences, such as the option of gummies alongside traditional tablets.

“Our pharmacy teams are available to offer advice and support to customers seeking to understand whether supplements are right for them and which format may best suit their individual needs.”

A Holland & Barrett spokeswoman said: “At Holland & Barrett, we believe customers should have access to clear information and a choice of supplements that suit their individual needs, preferences and budgets.

“Our magnesium gummies provide 150mg of magnesium per daily serving, equivalent to 40% of the Nutrient Reference Value. This makes a meaningful contribution to daily intake. Importantly, the NRV is a reference value for nutritional labelling, not a target that needs to be met through supplementation alone, as magnesium is also obtained through food.

“Gummies offer a convenient alternative for customers who prefer not to take tablets or capsules. Ingredients such as gelling agents and sweeteners have a functional role in achieving the taste, texture and structure of gummies.

“We recognise that traditional tablets can provide higher doses at a lower cost, which is why we offer a range of formats, including our Magnesium Citrate tablets providing 300mg per daily serving, to help customers make informed choices.”