How We Test Dietary Supplements

Our mission at NCOA is to improve the lives of millions of older adults. That's why we test and recommend dietary supplements that may support your health. Our goal is to help you find high-quality, reliable, and affordable options. We look for supplements that meet our safety and quality criteria, and assess the potential for unwanted side effects.

To begin our testing process, we reviewed research on dietary supplements and their effectiveness. Then, we surveyed our network of older adults about which supplements they take and what they value most when choosing one. Registered dietitians (RDs) reviewed the research on ingredient dosages and assessed how the amounts in each supplement compare. Our RDs also provided insight on the potential benefits and drawbacks of taking them.  

We reviewed customer feedback on platforms such as the Better Business Bureau (BBB) and Trustpilot to better understand people's experiences with supplement brands. This feedback helped us understand those experiences and narrow the supplements we tested. Then we began testing. 

How we rank and review dietary supplements

To test dietary supplements, we first had to understand which qualities matter most. So we went straight to the source: our surveys of older adults. Many of our survey participants take supplements for digestive and muscle health, as well as overall daily wellness.

Based on our survey findings, we created more than 24 tests. Each test results in a score, which is weighted according to the following factors:   

Quality and transparency (25% of score): We assess each supplement company's claims about third-party testing for safety and quality. We also look at each company's legal track record and brand reputation. Ingredient disclosure is another factor in our 1–5 scoring. Brands with clear allergen disclosures and complete Supplement Facts labels earn higher scores. 

Ease of use (20% of score): Our older adult testers try each supplement and rate its ease of use on a scale of 1–5. They assess packaging, instruction clarity, and mixability for powders or swallowability for capsules. Taking multiple capsules or scoops of powder can deter regular supplement use. So we also factor in the serving size of each. 

Formulation (15% of score): We look at how much of each active ingredient the supplement contains. We also research whether it comes from high-quality, clearly labeled sources. For example, we rate protein supplements on a 1–5 scale. We evaluate grams of protein per serving, the protein source, the protein-to-calorie ratio, added sugar, and the complexity of the ingredient list. We adjust these criteria to match each supplement category we test. For each supplement type, we assess whether evidence-based dosing is provided.   

Testing experience (15% of score): After trying each supplement, our older adult testers weigh in on factors such as taste and sweetness, assigning each category a 1–5 ranking. Testers also report unwanted effects they experience while trying each supplement, such as digestive discomfort, bloating, or an unpleasant aftertaste. We factor these experiences into the testing score.

Value (15% of score): Because accessibility is central to NCOA's mission, we always evaluate the affordability of every product we test. For supplements, we look at cost per serving and cost per day, plus subscription savings and shipping costs. Supplements with lower costs per serving and ongoing discounts earn higher scores in this category. 

Customer experience (10% of score): Our testers mystery shop products and look at the buying experience. We compare refund policies, customer support options, and other relevant elements. We also assess how easy it is to cancel a subscription, so you can order with more confidence that you won't get locked into an unwanted contract.