I have been taking 1 of teaspoon of this product and 1/4 teaspoon of BulkSupplements L-Arginine twice daily, for a week now. I can confidently say that it really works, I feel my muscles work better while working out, my skin and hair feels smoother. It has no side effects other than that it gives me minor headaches after drinking it, I guess I am not taking the right amount. That's why I'm giving this product 5 stars, and not less, because I don't think the side effect is because of the quality of the product, but because of me not choosing the right amount. I will update the review later when I find out.