Agar has E-number 406. It is an indigestible carbohydrate (polysaccharide) extracted from seaweed and various red algae. It does not contain fats or cholesterol but contains, among other things, the base-forming minerals potassium, magnesium and calcium. There are no health issues associated with agar.
It is used as a thickener just like husblas and gelatin. Agar is accepted by all religious groups, vegetarians and vegans.