Eight checks that take about a minute. They work on any supplement, ours included.
1. Find the amount of the nutrient itself
A mineral is always bound to something else. What matters is how much of the mineral you get, sometimes called the elemental amount. The nutrition table should state it plainly, for example "Magnesium 300mg". A big number on the front can describe the whole compound, which is a different thing.
2. Look for the form
The ingredients list names the form used: magnesium bisglycinate, citrate or oxide; vitamin D3 or D2; vitamin K2 as MK-7 or MK-4. If the form matters to you, it should be written down. If it is not there, ask.
3. Read the %NRV column
NRV means Nutrient Reference Value, the daily amount set for labelling. The percentage tells you how the dose compares with it. Some ingredients, such as collagen, have no NRV, so the column is left blank or marked accordingly.
4. Be wary of "blend" and "complex"
A proprietary blend gives one total weight for several ingredients. You cannot tell how much of each is inside. Twelve ingredients sharing one small capsule leaves very little room for any of them.
5. Check extract sums
"5000mg" on a herbal product often means a small amount of concentrated extract described as its fresh-plant equivalent. Look for the actual weight of extract in the capsule and the ratio, such as 10:1.
6. Per capsule or per serving?
Doses are sometimes quoted for two or three capsules. Divide the capsule count by the daily serving to see how many days the pot really lasts.
7. Read the other ingredients
Capsule shell, bulking agents and anti-caking agents are all listed. This is also where you find allergens, such as fish, and whether a capsule is suitable for vegetarians.
8. Notice how claims are worded
In Great Britain, health claims on food supplements have to come from an authorised list and use set wording, such as "contributes to a reduction of tiredness and fatigue". A food supplement must not claim to treat, cure or prevent any condition. Wording that promises more than that is a reason to look closer.
Food supplements should not be used as a substitute for a varied, balanced diet and a healthy lifestyle.