Proprietary blends hide individual ingredient doses. Why they exist, what they conceal and why WellnessChecked considers them a negative quality signal in every review.
A proprietary blend is a combination of ingredients listed under a single group dose without disclosing individual amounts. Manufacturers use them to hide the fact that individual ingredients are present at sub-therapeutic doses — allowing inclusion of fashionable ingredients on the label without providing the clinical doses that produce meaningful effects.
A supplement label might show: 'Testosterone Support Matrix 750mg: KSM-66® Ashwagandha, Fenugreek Seed Extract, Zinc, Vitamin D3'. You know the combined amount is 750mg — but not how much of each ingredient is present. If the product includes 600mg of ashwagandha (the clinical dose), there is only 150mg left for three other ingredients. If it includes 50mg of ashwagandha, there is 700mg for the others.
The stated reason is often 'protecting the formula'. The actual reason is usually to allow inclusion of popular ingredients at micro-doses — sometimes a few milligrams — without the buyer being able to identify the under-dosing. A transparent label from a confident manufacturer should show every individual ingredient amount.
If you cannot calculate whether each ingredient in a supplement is present at its clinical dose — because the amounts are hidden in a proprietary blend — you cannot verify the product's efficacy. This is the fundamental problem with proprietary blends.