Flaxseed is very safe! It's used for many conditions, but mostly for lowering risk of Heart Disease, Cancer prevention, Constipation, Anti-Inflammatory, Lowering Cholesterol, Weight Management, Attention Deficit in children....the list is long! It contains the Omega 3 Fatty Acid which is part of the Essential Fatty Acids needed for a healthy body. It won't raise your metabolism, but it can help in weight loss if used with a sensible diet, but most people are taking it for a healthier heart! It's a food and can be taken in various ways from the ground flaxseed, the oil, or in capsules.