Within the E.U. the European Commission consider a product labeled as or 'claims' to be a source of protein must contain at least 12% and a high-protein product — or one labeled as such to likely have the same meaning for the consumer must be at least 20% protein.
A nutritional 'claim' means any claim which states, suggests or
implies that a food has particular beneficial nutritional properties
The energy (calorific value) it:
- (a) provides
- (b) provides at a reduced or increased rate or
- (c) does not provide
The nutrients or other substances it:
- (a) contains
- (b) contains in reduced or increased proportions or
- (c) does not contain
Your bar then — having 29.6% protein — is indeed high-protein. In the E.U.
In the U.S. it is more difficult to define.
The Food & Drug Administration state:
In the U.S., similarly a product "high," "rich in" or described in "excellent source of":
Contains 20% or more of the DV per RACC. May be used on meals or main
dishes to indicate that the product contains a food that meets the
definition, but may not be used to describe the meal.
DV being Percent Daily Value and RACC being Reference Amounts Customarily Consumed.
From the Frequently Asked Questions for Industry on Nutrition Facts Labeling Requirements factsheet the RACC for most cooked meats and fish is 85g.
So for a meat to be high-protein it must have 17g (20%) of protein if the RACC was 85g.
This would vary by protein source, however.
In general, the 20% mark is considered to be high-protein.