The snack bars that claim to be anti-inflammatory, good for concentration... and can even keep ageing at bay - rated and tested by dietitian ROSIE CARR

Snack bars aren't 'just' food – some promise to help you concentrate better, fight inflammation and even keep your skin looking young. Dietitian Rosie Carr from weight-loss website Second Nature assessed a selection – which we rated and tasted.

Jade & Joy Marshmallow Biscuit Vegan Collagen, 50g, £1.66, hollandandbarrett.com

PER BAR: Calories, 179; saturated fat, 2.5g; protein, 15g; fibre, 3.7g; sugar, 2.1g; salt, 0.25g.

CLAIM: 'Halt signs of ageing. Formulated to kick-start internal collagen production. Proven to hydrate skin and strengthen hair and nails.'

EXPERT VERDICT: Pea and soya protein are the main ingredients but consuming amino acids – the building blocks of collagen – like this won't translate to improved skin, hair or nails.

The claims about vegan collagen 'halting signs of ageing' and 'proven' skin benefits are unsupported by robust evidence.

The protein content – two large eggs' worth – is the highest here, but this bar is lower in fibre than most and the maltitol (a sweetener), polydextrose (a soluble fibre) and other additives make this an ultra-processed food. 2/10

TASTE: Chocolate treat with powdery aftertaste.

Rheal Energy Caffeinated Superfood Bar Blueberry Muffin, 40g, £1.33, hollandandbarrett.com

PER BAR: Calories, 173; saturated fat, 2.3g; protein, 3.6g; fibre, 5.7g; sugar, 6.7g; salt, 0.2g.

CLAIM: 'The perfect pick-me-up for lasting energy. Coeliac-friendly oat bar with guarana. Provides 68mg caffeine per bar (equivalent to a single espresso) plus 5.7g gut-friendly fibre.'

EXPERT VERDICT: Guarana is naturally high in caffeine, but the other ingredients will slow its absorption. The energy boost is likely to come from the teaspoon-and-a-half of added sugar from date syrup, brown rice syrup and coconut sugar.

The combination of caffeine and sugar will likely give an energy spike followed by a crash but a bar will also provide 19 per cent of your daily fibre. 5/10

TASTE: Nutty, but lacking in blueberry flavour.

Butter High Fibre Bar, 35g, £1.30 sainsburys.co.uk

PER BAR: Calories, 122; saturated fat, 0.7g; protein, 2.8g; fibre, 10.4g; sugar, 11.5g; salt, 0.08g.

CLAIM: 'A third of your daily fibre in a bar. Food for your gut bugs that has anti-inflammatory effects.'

EXPERT VERDICT: Just six simple ingredients (date paste, chicory fibre, peanuts, sunflower seeds, sunflower oil and sea salt), which is a good thing.

With a third of your daily fibre, it should be filling, while the insoluble fibre (from the dates, chicory and peanuts) will help with healthy bowel function.

Peanuts are a good source of heart-friendly fats, plant sterols and antioxidants. However a handful of mixed nuts would provide similar nutrition without the sugar spikes. 6/10

TASTE: Good peanut flavour but super sweet.

M&S Brain Food Mixed Berry Bar, 35g, £1, ocado.com

PER BAR: Calories, 134.4; saturated fat, 0.45g; protein, 3.64g; fibre, 4.76g; sugar, 14g; salt, 0.01g.

CLAIM: 'Helps support brain health. High in iron and zinc, which contribute to normal cognitive function. High in fibre, vitamin C, vitamin D.'

EXPERT VERDICT: A mix of date paste, almonds, chicory fibre, freeze-dried berries and added vitamins, iron and zinc.

Iron and zinc contribute to cognitive function, although a balanced diet is a better source than a fortified snack bar.

The 40 per cent sugar content (higher than some chocolate bars) comes from the date paste and dried fruit, but 'natural' sugars can cause blood sugar spikes (and may impair concentration). 4/10

TASTE: Tangy fruit flavour.