Can you really trust food supplements?

There are several food supplements found online, like Aloe Vera juice and other Aloe Vera products. But are these really safe and effective? Though information online, such as samples of personal statements for scholarships and sample essay about myself , can be easily found, relevant info about these health products are not. There are studies about Aloe Vera , but they are about the Aloe Vera plant and not the products themselves. So, how can one decide which product to trust? Also, since governments don’t test the effectiveness of these products, how can one determine whether these products are really worth it? Is there any reliable resource we can refer to?