Anyway, the topic here isn't my only reason for ordering these. I'm interested in them for culinary purposes, for flavor (especially citric acid). I'm also interested in citric acid for other health purposes (I tend to feel good when I eat things that contain it, whether or not that's the reason).
Be careful when adding acids to foods. Do your research, since sometimes reactions with chemicals in the food may create toxins. You'll want to study soda pop and vitamin C if you're tempted to mix them. Sodium benzoate, potassium benzoate, and calcium benzoate can react with vitamin C to create the toxin, benzene: en.wikipedia.org/wiki/Benzene_in_soft_drinks
I should note that selenium is good in healthy amounts. However, there is such a thing as too much, and there is too much in our water, as I've seen on our water reports (probably because of fracking for natural gas, which is done in the area—but I could potentially be wrong about that being the cause in this case; I don't believe our water tested positive for high levels of arsenic).
Before you take selenium supplements, please look at your local water report.