How Do You Know If a Health Supplement is Worth Buying? When it comes to buying a supplement, it can be confusing. There are so many different products, and they all promise to do great things. However, some of these claims are merely false assertions, but others are true. So, how can you tell which product is worth buying, and which one isn’t’? For the purpose of this article, we’re going to use the example of Threelac. This is because it’s a common supplement, and so it’s easy to highlight what we mean by each point made below. There are many Threelac reviews and much evidence, so it’s a relatively easy supplement for us to use to explain how you would know it was worth buying.