Best Gluten Free Energy Bars UK: 10 Checked on Their Own Labels

Written by James Frost, founder of Flaming Phoenix. Updated October 2026.

A UK energy bar labelled gluten free must contain no more than 20 parts per million of gluten. Of the bars I checked in October 2026, my top pick is Phoenix Bars: labelled gluten-free, made with gluten-free oats, and carrying the most calories and the most protein per bar of the ten, up to 557 calories and 18 to 19g of protein in a compact, 120g bar. The other nine follow below, from most calories to fewest, with the oat status and gluten line for each.

Phoenix Bars are mine, and they appear below with the same checks as the rest. For each bar I looked at three things: whether the label makes the legal "gluten free" claim, whether the oats are gluten-free oats or there are no oats at all, and what the may-contain or factory line says about gluten. Figures come from brand pages and UK supermarket or retailer listings opened in October 2026, linked at the foot of the page.

What does gluten free mean on a UK label?

A bar labelled gluten free must contain no more than 20 parts per million (20mg per kg) of gluten as sold, whether that gluten would come from an ingredient or from cross-contamination in the factory.

The rule sits in Regulation 828/2014, which the UK kept after leaving the EU. The same law allows "very low gluten" at up to 100mg per kg, and says oats in a gluten-free food must have been "specially produced, prepared and/or processed in a way to avoid contamination by wheat, rye, barley". The Food Standards Agency's guidance adds that the limit applies "irrespective of whether the gluten is present as a deliberate ingredient or as a result of cross contamination". The NHS guidance on going gluten-free gives the same 20 parts per million figure and warns that additives such as malt flavouring can contain gluten.

The gluten-free energy bars, from most calories to fewest

Ten bars whose label or listing says gluten free, with the oat status and the gluten line from the pack. Calories are per bar.

1. Phoenix Bars: 529 to 557 calories in only 120g, 18 to 19g of protein. Gluten-free rolled oats and gluten-free oat flour. The label also says they are made in an environment that handles gluten. £5.25.
2. KMC NRG Bar: 85g with 83g of carbohydrate, roughly 330 calories, almost all sugar. No oats. Made in a factory that handles nuts and peanuts.
3. Styrkr BAR50 Dark Chocolate Chip: 249 calories in 70g, 50.4g of carbohydrate. Crisp rice, no oats. The facility statement on Styrkr's page lists milk, egg, nuts, peanuts, sulphites and sesame, not gluten.
4. Veloforte Di Bosco: 238 calories in 55g. Dried fruit, nuts, gram flour and tapioca, no oats; Veloforte says every bar in its range is gluten free.
5. Trek Protein Flapjack Cocoa Oat: 227 calories in 50g, 9g of protein. 25% gluten-free oats. May contain peanuts, nuts and milk.
6. Deliciously Ella Cacao & Orange oat bar: 209 calories in 50g. 49% gluten-free oats.
7. Nature Valley Protein Peanut & Chocolate: 196 calories in 40g, 10g of protein from peanuts and soy. No oats. Contains milk.
8. Free Soul vegan protein bar: 164 calories and 15g of protein; weight not given on Free Soul's page.
9. Freee Chocolate Chip Oat Bar: 141 calories in 35g. 39% gluten-free oats, third-party gluten-free certification, and no may-contain statement on Freee's page.
10. Nakd Cocoa Delight: 135 calories in 35g of dates, cashews, raisins and cocoa. No oats. Premcrest lists it as gluten free.

Phoenix Bars sit first on calories and on protein per bar, which makes them the pick for a long day out; for a light desk snack, the smaller bars at the bottom are plenty.

What's a good gluten-free protein bar?

For a bar that is actually labelled gluten free and carries a useful amount of protein, Phoenix Bars lead with 18 to 19g, alongside 529 to 557 calories, for long days out. For a lighter snack, Free Soul (15g), Nature Valley Protein (10g) and Trek Protein Flapjack (9g) are the others I found on UK shelves.

Nature Valley Protein contains milk; Phoenix Bars, Free Soul and Trek are plant-based.

Plenty of 20g protein bars contain no gluten ingredients but stop short of the label claim. A Barebells Salty Peanut bar (200 calories, 20g of protein from milk protein, collagen and soy) and a Grenade Chocolate Chip Salted Caramel bar (222 calories, 20g of protein) both say "may contain cereals containing gluten". The Food Standards Agency's guidance treats "no gluten-containing ingredients" as a factual statement with no threshold behind it, so if you need to avoid gluten strictly, the gluten-free claim is the line to trust.

Which gluten-free bars contain no oats?

Styrkr BAR50, Veloforte Di Bosco, Nakd, the KMC NRG Bar and Nature Valley Protein have no oats in their ingredients, which also answers the question of which bars are made without any gluten-containing cereals.

UK allergen labels count oats among the cereals containing gluten, which is why Trek and Deliciously Ella print oats in bold even though their oats are gluten-free. The NHS explains that oats contain a protein called avenin that a few people who avoid gluten still react to, and advises avoiding oat products that are not labelled gluten-free. If oats are a problem for you, the five above are the place to start; read the full ingredients each time, because recipes change.

Look-alikes that contain gluten

These sit next to the bars above on the shelf and are easy to pick up by mistake.

• Clif Bar Chocolate Chip: standard rolled oats plus barley malt extract, and may contain wheat and rye, according to Hancocks' listing. No gluten-free claim.
• Nature Valley Crunchy Oats & Honey: 60% whole grain oats, not sold as gluten-free oats, and may contain wheat, on Tesco's page. The same brand's Protein bar is labelled gluten free, so check each bar.

How to read "may contain gluten" and "made in a factory that handles gluten"

A may-contain line is voluntary, so its absence proves nothing, and its presence on a bar without a gluten-free claim means the maker will not promise the 20 parts per million limit.

The Food Standards Agency's guidance says there is "no legal requirement to use 'may contain' or 'traces of' type warnings". When a bar carries both a gluten-free claim and a factory line, as Phoenix Bars do ("made in an environment that handles egg, gluten, milk, nuts, peanuts, sesame, soy and sulphites"), the claim still has to hold at 20 parts per million as sold; the factory line tells you gluten is handled on site.

Common questions

Are oats gluten free?
Oats do not contain gluten themselves, but standard oats can be contaminated by wheat or barley in the field or the mill. Only oats sold as gluten free meet the 20 parts per million limit, so look for "gluten free oats" in the ingredients: Phoenix Bars use gluten-free rolled oats and gluten-free oat flour, Trek uses 25%, Freee 39% and Deliciously Ella 49%.

Where can I find gluten-free protein bars in the UK?
Phoenix Bars are sold direct from our website and posted within 1 working day. Supermarkets such as Tesco stock Trek Protein Flapjack and Nature Valley Protein, and sports bars such as Styrkr and the KMC NRG Bar are sold by cycling and outdoor shops.

Are flapjacks gluten free?
Only if they are made with gluten-free oats and labelled that way; a traditional flapjack made with standard oats is not. Our page on gluten free flapjacks has a recipe and the UK ones worth buying, and our high calorie porridge guide covers oat breakfasts.

Are these gluten-free bars vegan as well?
All except Nature Valley Protein, which contains milk; the KMC NRG Bar's vegan wording is inconsistent, so check its wrapper. Our comparison of the best vegan energy bars UK checks protein sources and honey, and for food beyond bars see high calorie gluten free foods. For long days on foot, the best energy bars for ultra running and best energy bars for hiking compare bars on the move, and our high calorie bars page covers Phoenix Bars in full.

Sources, checked October 2026: NHS, gluten-free diet and oats; Regulation (EU) No 828/2014 as retained in UK law; Food Standards Agency, guidance on gluten-free labelling (2012); product pages for Trek, Deliciously Ella, Nature Valley (Tesco), Freee, Styrkr, Veloforte, KMC NRG Bar (Mountain Warehouse), Free Soul, Nakd (Premcrest), Barebells and Grenade (Ocado) and Clif Bar (Hancocks). Flaming Phoenix is not affiliated with any other brand named here, and all trademarks belong to their owners.