Before You Start a Mineral Supplement: A Safety Checklist

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This is a checklist of things to check, not a recommendation to take any mineral. The FDA advises talking to a doctor, pharmacist or other healthcare professional before deciding to buy or use a dietary supplement, because supplements can involve health risks as well as benefits. [1] MedlinePlus lists the basics: tell your health care provider about supplements you use, do not take a bigger dose than the label recommends, and check with your provider before any surgery. [2]

Urgent. If a child may have swallowed iron or any supplement, call Poison Help (US) at 1-800-222-1222, or 911 if the child is unwell, and see Poison Help by country. The NHS says very high doses of iron can be fatal, particularly in children. [3]

Step 1: Be clear about the reason

Write down why you are considering the supplement and what you hope it will do. Ask whether there is a reason to think you are low in the mineral and how a clinician would check. Symptoms alone do not show which mineral, if any, is low. The NHS says that for calcium, iron, magnesium and several other minerals you should be able to get all you need from a varied, balanced diet. [4][3][5] See mineral blood tests. NCCIH notes that the amount of scientific evidence on dietary supplements varies widely, and that supplements bought in stores may differ from products tested in studies. [6]

Step 2: Check the label

• Elemental amount. The Supplement Facts panel lists the weight of the mineral (for calcium, calcium rather than calcium carbonate). [7] See reading a mineral supplement label.
• Form. Is the form named, such as "as magnesium oxide"? Forms differ; see mineral supplement forms.
• Serving size. Is the serving one tablet or several? Amounts are per serving. [7]
• Other ingredients. Binders and fillers are listed in the ingredient statement below the panel. [7] Look for other minerals or vitamins, and for salt in dissolvable tablets. [8]
• Percent Daily Value. It is a label yardstick and not a limit. [9]
• Quality. What is on the label may not be what is in the product, according to NCCIH. [6] See quality testing and certifications.

Step 3: Add up the total

Many people take more than one product that contains the same mineral, such as a multivitamin with minerals, a separate calcium or zinc product, an antacid, and fortified foods. Add the amounts from supplements together, then compare with the published upper level for your age and sex.

These are a different thing from a recommended intake. They are ceilings for adults in general, and they do not apply to pregnancy, children or people with certain conditions in the same way. The full tables are in mineral intake reference tables, and the risks of too much are in mineral toxicity and upper limits.

Step 4: Check medicines

Some minerals change how medicines are absorbed. The NHS pages list calcium and iron supplements and antacids for levothyroxine, [12] iron, zinc and antacids for doxycycline, [13] and says to leave at least 2 hours between ciprofloxacin and dairy products or calcium-added drinks. [14] Ask a pharmacist to check every medicine you take. Never stop or change a prescribed medicine on your own. See medicine interactions.

Step 5: Check your health conditions

• Kidney disease. MedlinePlus advises talking to a provider before taking potassium supplements if you have kidney disease, [15] and says magnesium excess is uncommon except in people with significantly reduced kidney function. [16] See minerals and kidney disease.
• Iron overload. In haemochromatosis the NHS says people are usually advised to avoid iron or vitamin C supplements. [17]
• Thyroid. Long-term high iodine can change how the thyroid works, according to the NHS. [11]
• Other conditions. Ask whether any other condition you have, such as a heart, liver or bowel condition, changes the picture.

Step 6: Life stage

Many supplements have not been tested in pregnant women, nursing mothers or children. [6] Ask before using any mineral product in pregnancy, while breastfeeding, for a child or in later life, and see prenatal and postnatal vitamins and minerals and older adults. The NHS advises avoiding liver in pregnancy, a food listed among iron sources. [3]

Step 7: Surgery and procedures

NCCIH says certain supplements may raise bleeding risk or affect anesthesia, and to tell your providers about all supplements as far ahead of an operation as possible. [6] See supplements before surgery.

Step 8: Storage and child safety

Keep all supplements out of reach of children; the NHS says very high doses of iron can be fatal, particularly if taken by children, and to keep iron supplements out of their reach. [3] Follow the instructions on the label. [6]

Step 9: Know what to do if something feels wrong

NCCIH says that if you have side effects, stop taking the supplement and contact your health care provider; you may also contact the manufacturer. [6] For severe symptoms, call 911 (US). Constipation, nausea and stomach pain are listed by the NHS as side effects of high iron doses. [3] NCCIH says safety concerns about a supplement can be reported through the U.S. Health and Human Services Safety Reporting Portal. [6]

Step 10: Take your questions with you

Use the list in questions to ask your clinician or pharmacist. For the whole library see Minerals and the mineral safety quick reference.