Allergen filtering in meal planning

There are two ways to build allergen filtering into a meal-plan generator, and the difference matters for safety. The first generates the plan, then flags the meals containing an allergen. The second excludes the allergen during generation, so by the time you see the plan that ingredient was never in it. Cookrange takes the second route: the filter is applied before the plan is shown.

Why the order matters

The problem with flagging is on the human side. A warning label only works if it is read, and across a 28-meal weekly plan, missing labels is the rule rather than the exception. With exclusion there is no warning to miss, because the risky meal never entered the list. Two designs aiming at the same outcome, but one depends on the user's attention and the other does not.

In practice: on a profile with peanut and shellfish constraints, no meal in the generated week contains them. Regenerate the plan and the constraint applies to the new plan the same way, because the constraint belongs to the profile rather than to any single plan.

What the filter does not guarantee

This is the most important section on the page and it is deliberately not hidden. An allergen filter is a preference filter, not a medical guarantee. It has three distinct limits:

• Cross-contamination is unknowable. The filter knows a recipe's ingredient list. It cannot know the kitchen it was prepared in, the surface used, or the facility a product was made in. With a serious allergy, most of the risk sits exactly there.
• Packaged products depend on label data. Ingredient information for items added by barcode comes from Open Food Facts, which is community-contributed. When a manufacturer reformulates, the database can lag.
• Hidden names and derivatives can be missed. One allergen can appear under dozens of names. The filter catches the names it knows; it cannot catch a derivative it does not.

So, plainly: if you have a diagnosed serious food allergy, no app's filter should be trusted on its own. Reading the label yourself continues alongside using the filter. Cookrange is not a medical device and does not claim to be.

Constraints and preferences are not the same thing

The filter handles two different things through one mechanism, and the difference matters to the person using it. A constraint is what must not be there: an allergy, an intolerance, a religious or ethical boundary. A preference is what you would rather avoid. Both are removed from the plan, but not with equal weight: bending a preference once is reasonable, bending a constraint is not. The interface keeps that distinction.

How it is set up in Cookrange

Constraints are defined at profile level, not per plan. The reason for that design choice is repeatability: if regenerating a plan required re-entering every constraint, that step would be the most likely one to get skipped at exactly the moment it mattered most. Details onnutrition and planning; how the plan itself is produced is on AI meal planning.