Not that I have noticed. They are made from beans and contain oligosaccharides which are broken down by bacteria. Unlike cellulose based carbs which are not broken down at all and which can have a laxative effect, beans don't. However, because they are broken down by bacteria, they can cause wind, but it is only mild.
They do absorb the taste of a sauce well. If you can eat beans and lentils etc, you should be OK with them.
Many asian and chinese foodstores sell stuff at a fraction of the prices in supermarkets.