How to Spot Filler Ingredients in Your Supplements

What Are Filler Ingredients?

Filler ingredients are non-nutritive substances added to supplements to bulk up the product, improve texture, or reduce costs. Common examples include magnesium stearate, starch, and silicon dioxide. While not always harmful, they can dilute the potency of active ingredients and may cause digestive discomfort in sensitive individuals.

Common Filler Ingredients to Watch For

• Magnesium Stearate: A flow agent that can coat the gut and reduce nutrient absorption.
• Microcrystalline Cellulose: A plant-derived filler used to bind tablets.
• Silicon Dioxide: Added to prevent clumping but offers no nutritional value.
• Corn Starch: Often used in capsules; may trigger allergies.

How to Read Supplement Labels

Always check the ingredients list in order of weight. Ingredients listed near the bottom contribute less to the product’s composition. Look for terms like "proprietary blend"—this means active and inactive ingredients are combined, making it hard to assess potency. Compare labels with our guide to supplement labeling for clarity.

Red Flags for Hidden Fillers

Products with vague descriptions (e.g., "natural flavoring") often hide fillers. If a supplement promises high potency but lists multiple bulking agents, it may be misleading. Also, beware of unnecessary additives like artificial colors or coatings, which serve no health purpose.