Understanding the ingredients
The supplement world is full of claims and short on sources. In these guides we explain what each ingredient is, what research shows, and where the evidence is weak, as it is.
Start with your complaint
13 topicsWhat is magnesium’s role in sleep problems?
Does magnesium shorten the time it takes to fall asleep? A meta-analysis of three trials, the forms used in the evening, and the limits of the evidence.
Read ComplaintWhat does magnesium do for stress and tension?
Which claims are authorised, what an 18-study review found, and why no one may say magnesium reduces stress.
Read ComplaintDoes magnesium help with muscle cramps?
The Cochrane review’s conclusion, the situation with night leg cramps, and the common misconception about cramps in athletes.
Read ComplaintCould constant tiredness be magnesium deficiency?
Magnesium has an authorised claim here. What the claim says, where it ends, and what else causes persistent tiredness.
Read ComplaintWhat does the research say about magnesium and migraine?
How systematic reviews grade the evidence, the 600 mg citrate dose used in trials, and why that is a clinical decision.
Read ComplaintMagnesium for premenstrual symptoms
The scope of the randomised evidence, how it compares with calcium, and what is known about the mechanism.
Read ComplaintDoes magnesium have a role in restless legs syndrome?
Two systematic reviews, two different conclusions. Why they differ, and why iron should be checked first.
Read PerformanceHow important is magnesium for people who train?
The real scale of sweat losses, what performance trials found, and which athletes are genuinely at risk of a shortfall.
Read IngredientWhat do caffeine and L-theanine do together for focus?
Why EFSA attributed the attention claim to caffeine, the claim status of L-theanine, and what the combination studies found.
Read IngredientCoenzyme Q10 and the heart: what is known?
Heart failure and statin muscle research on coenzyme Q10 — and the fact that no health claim is authorised.
Read SafetySupplement use in pregnancy and breastfeeding
Why the decision belongs to your doctor, what the evidence shows on cramps in pregnancy, and what to tell your clinician.
Read SafetyWhich medicines does magnesium interfere with?
Conflicts with antibiotics, thyroid medication, bisphosphonates and stomach medicines — and the spacing table.
Read SafetyCan you take magnesium if you have kidney disease?
The kidney clears magnesium. What happens when function falls, what the data in chronic kidney disease show, and what to do.
ReadCannot find what you are looking for? Use the search box at the top and type your complaint in your own words. The search covers every heading and paragraph in these guides.
Understanding the ingredients
4 guidesWhat is the difference between magnesium forms?
Malate, L-threonate, bisglycinate, taurate, citrate and oxide compared for absorption, stomach tolerance and timing.
Read IngredientWhat is L-theanine, and what does it really do?
The amino acid of green tea, its pairing with caffeine, and what regulators decided about health claims.
Read IngredientWhat is coenzyme Q10, and what does it do?
Its role in mitochondria, ubiquinone versus ubiquinol, practical notes on absorption and the state of the evidence.
Read NutritionWhy can magnesium intake fall short?
Why intake can fall short, magnesium-rich foods, and what the reference value really means.
ReadOur writing rule: if a claim about an ingredient has not been authorised by regulators, we say so. We keep authorised health claims and research findings apart. Our aim is to give accurate information before selling anything.
The content on these pages is for information only and is not medical advice, diagnosis or treatment. Food supplements should not be used as a substitute for a varied and balanced diet and are not intended to prevent or treat any disease. Do not exceed the recommended daily dose.