In a recent paper, Parle, Martinez and Roman (2026, Annual Review of Food Science and Technology, Vol. 17:51-77) set out the precise numerical thresholds behind protein claims on bread packaging from commercially available protein-fortified breads across different geographical regions and the gap between "source of protein" and "high-protein" is narrower than many formulators assume.

The two regulatory systems

Under EU Regulation No 1924/2006, a product may be labelled a "source of protein" if at least 12% of its energy content derives from protein. To carry a "high-protein" (HP) claim, that proportion must reach 20% or more.

The US Food and Drug Administration works differently, basing protein claims on the percentage of the Daily Reference Value (DRV), set at 50 g of protein per day. A "source of protein" claim requires 10 to 19% of the DRV per serving, while a HP claim requires at least 20% (FDA, 21 CFR §101.54).

Where conventional bread already sits

Conventional white loaf bread (around 9 g protein per 100 g) derives approximately 14% of its energy from protein. That is enough to meet the "source of protein" threshold, but not HP.

Whole-wheat bread fares a little better. At roughly 11 g protein per 100 g, it reaches around 18% of energy from protein, still short of the 20% HP mark.

The fortification target

To cross the HP threshold, formulators need to reach at least 13 g protein per 100 g, based on the calorie content of conventional white formulations. That represents an increase of roughly 45% over the conventional baseline.

This target is not fixed, however. It depends on the product's total energy value. Low-carbohydrate formulations tend to carry lower total energy, so a smaller absolute quantity of protein can still deliver a higher proportion of calories and therefore qualify for HP status with less protein added overall.

What this means at the point of consumption

Using a typical serving size of 50 g, a bread product at the minimum HP threshold would provide around 6.5 g of protein per portion.

Set against recommended intakes of 0.8 to 0.83 g per kg body weight per day (56 to 58 g per day for a 70 kg adult), a single HP bread serving would meet around 11% of daily protein needs.

In practice, most commercial products exceed the minimum threshold by some margin, to allow for manufacturing variation while keeping the HP claim secure.

The "low-carb" grey area

Manufacturers developing low-carbohydrate or "keto" SKUs alongside protein claims should note that neither term carries a harmonised legal definition.

In the US, "low-carb" is not formally defined under 21 CFR Part 101. Manufacturers may use it provided it is not misleading, under the Federal Food, Drug and Cosmetic Act, which leaves interpretation largely to the manufacturer.

In the EU, Regulation No 1924/2006 requires at least a 30% reduction compared with a reference product for claims such as "reduced [nutrient]." Carbohydrates are not explicitly named in the regulation, but low-carb claims must still satisfy this general reduction threshold.

"Keto" remains unregulated in both jurisdictions. This regulatory gap contributes to considerable variation in the carbohydrate content of products carrying these claims and is worth factoring into label review before launch.