If you're vegan or vegetarian, you know the struggle of meeting your protein needs. Of course, with proper planning and research, it can absolutely be done. In an effort to ease the process, many vegan and vegetarian athletes turn to vegan protein powders – products that are designed to help you get a solid dose of protein in a convenient package. But, just because it's labeled as “vegan” doesn't mean that that particular product is automatically your best choice. In fact, there are many things that are added to vegan protein powders that are... less than desirable. There is one substance, in particular, that is extremely common in vegan protein powders that you need to be aware of. More to the point, you should avoid this chemical. The Culprit Namely, we're looking at a substance called “soy protein isolate.” As you may have noticed, vegan protein powders rarely consist of just one protein source (a practice that creates a whole list of other problems that we won't discuss here). Among the most common powders thrown in the mix is a protein derived from the soy bean and processed so that it contains a higher concentration of protein than other options. But what's the problem? Soy, despite its sterling reputation as a rare plant source of complete protein, raises several concerns. For one, soy can cause severe allergic reactions in some individuals. This immediately makes the common practice of adding soy to protein powders a risky move. If you have a known allergy to soy, you will want to be careful to avoid any vegan protein powder that contains soy protein isolate or any other soy products. But things don't just stop at allergies. Soy also contains chemicals known as phytoestrogens – substances that act like estrogen in the human body. While the research has been mixed and somewhat controversial, there is some evidence to show that regular soy intake can cause hormone disruptions and even increase your risk of developing certain types of cancer. Ultimately... As is often the case, the poison is in the dose. Small amounts of soy seem to be safe but, how often do you take your protein powder? Generally, it's a daily occurrence. Is there any room, then, for a chemical that is potentially dangerous in high doses? It should also be noted that soy – in various forms – is also found in just about every processed food we eat. There's a real possibility, then, that your soy intake is significantly higher than you realize. The reality is that many safer alternatives to soy exist. Manufacturers, however, often rely on soy because it's relatively cheap to produce and process. Read More: Is the Protein in Plant-Based Protein Powder Denatured? Vegan Diet:  How Much Protein per Day? 3 Myths About Plant Protein Powder