Natural Factors Vitamin B1 - 100 mg - Enhances circulation, and assists in blood formation and carbohydrate metabolism. Also beneficial for proper digestion, Vitamin B1 (Thiamine) is also important for cognitive activity and brain functions, and is needed for muscle tone in the intestines, stomach and heart. Vitamin B1 also acts as an anti-oxidant, protecting the body from the degenerative effects of aging, alcohol consumption and smoking.