I am partly at fault for ordering a 3 month supply of Dr. Mercola's Magnesium Threonate at a price of £110. I should have ordered a month's supply. I took under the recommended dose for 3 days and discovered that these capsules had an adverse effect on my health. I then read on a NHS website, that for some people, magnesium threonate can be harmful. The site stated that this type of magnesium can cause headaches, heart palpitations and excessive thirst for a minority of people. These are the exact symptoms I experienced. If taken for a prolonged period it is possible that I could have had a cardiac arrest. I stopped taking the capsules and within a week the symptoms disappeared. I wrongly presumed, as a result of this, that Oceans Alive would accept a return of the capsules. However their policy is that the bottle has to be returned unopened. I was disappointed that I lost £110 due to something out of my control.