Dietitian review finds popular 'functional' snack bars often overstate health benefits
Rosie Carr tested four bars marketed for anti-ageing, anti-inflammatory, energy and brain benefits and found nutritional trade-offs and overstated claims
A dietitian who assessed a selection of snack bars marketed with health‑boosting claims concluded that many of the promises are overstated and that nutritional trade‑offs vary by product.
Rosie Carr, a registered dietitian writing for weight‑loss website Second Nature, rated and tasted four bars being sold in UK retailers that claim to support skin, reduce inflammation, provide lasting energy or boost cognitive function. Her review gave the highest score to a simple high‑fibre bar and the lowest to a product billed as "vegan collagen" for anti‑ageing.
The Jade & Joy Marshmallow Biscuit Vegan Collagen bar, 50 grams and sold at Holland & Barrett for about £1.66, was rated 2 out of 10. It lists calories at 179, saturated fat 2.5 grams, protein 15 grams, fibre 3.7 grams, sugar 2.1 grams and salt 0.25 grams. The bar is promoted as able to "halt signs of ageing" and to "kick‑start internal collagen production," claims Carr said are not supported by robust evidence. While the bar contains pea and soy protein and delivers roughly the protein of two large eggs, Carr noted that consuming amino acids in this form does not directly translate into improved skin, hair or nails. She also flagged the product as ultra‑processed because of ingredients such as maltitol and polydextrose, and described its taste as a chocolate treat with a powdery aftertaste.
A caffeine‑containing option, Rheal Energy Caffeinated Superfood Bar in Blueberry Muffin flavour, 40 grams and priced at about £1.33, scored 5 out of 10. Per bar nutrition listed 173 calories, saturated fat 2.3 grams, protein 3.6 grams, fibre 5.7 grams, sugar 6.7 grams and salt 0.2 grams. The manufacturer promotes 68 milligrams of caffeine per bar—roughly equivalent to a single espresso—sourced from guarana, and highlights 5.7 grams of fibre. Carr said the caffeine is likely to produce a short‑term boost, but the added sugars from date syrup, brown rice syrup and coconut sugar could contribute to an energy spike followed by a crash. She also noted the bar provides about 19 percent of the reference daily amount for fibre and described the taste as nutty but lacking in blueberry flavour.
The Butter High Fibre Bar, 35 grams and sold at Sainsbury's for about £1.30, earned the highest score at 6 out of 10. Its label shows 122 calories, saturated fat 0.7 gram, protein 2.8 grams, fibre 10.4 grams, sugar 11.5 grams and salt 0.08 gram. Carr highlighted the product’s short ingredient list—date paste, chicory fibre, peanuts, sunflower seeds, sunflower oil and sea salt—and its provision of roughly one‑third of a day’s fibre. She said the insoluble fibre could support bowel function and that peanuts contribute heart‑friendly fats and antioxidants, but added that similar benefits could be obtained from a handful of mixed nuts without the added sugar. The Taste verdict noted a good peanut flavour but called the bar "super sweet."
A product marketed for cognitive support, M&S Brain Food Mixed Berry Bar, 35 grams and retailing for around £1, received a score of 4 out of 10. Nutrition information reported about 134 calories, saturated fat 0.45 gram, protein 3.64 grams, fibre 4.76 grams, sugar 14 grams and salt 0.01 gram. The packaging claims the bar is "high in iron and zinc, which contribute to normal cognitive function," and lists added vitamins. Carr observed that iron and zinc can support cognitive processes but that a balanced diet is a more reliable source than a fortified snack. She also warned that the roughly 40 percent sugar content—driven by date paste and dried fruit—could cause blood sugar spikes that may impair concentration, and described the taste as tangy fruit.
Carr’s assessments point to common themes: fortified or functional marketing does not guarantee meaningful clinical benefits, and nutrient content matters beyond single ingredients or added bioactive compounds. Several bars delivered useful amounts of fibre or protein, but sugar content, sweeteners and processing level were recurring concerns. In the case of products containing caffeine, experts note the interaction of caffeine with sugars and other ingredients can affect the duration and quality of any energy boost.
Nutrition professionals cited in the review recommended that consumers view such bars as occasional convenience foods rather than substitutes for a varied diet. Whole foods such as fruit, nuts, legumes, oily fish and whole grains remain primary sources for many of the nutrients linked to skin, brain and heart health, and evidence supporting targeted claims—such as "vegan collagen" reducing visible ageing—is limited.
Carr’s ratings and tasting notes offer a comparative snapshot for shoppers balancing convenience and marketed health claims. She emphasized reading ingredient lists and nutrition panels, particularly for sugar, fibre and protein content, and considering simpler, less‑processed alternatives for routine snacking.