Ghost Fitness/Magnesium/Is 300mg of vitabright magnesium glycinate the right daily dose?
Is 300mg of vitabright magnesium glycinate the right daily dose?
The short answer
Only if the 300mg is elemental: that sits at or above the adult reference nutrient intake, at 80% of the NRV and under the 400mg supplemental guidance level. If it is 300mg of bisglycinate, it is about 60mg of magnesium.
- Reference point one: the RNI300mg a day for adult men, 270mg for adult women: total intake from all sources
- Reference point two: the NRV375mg: the labelling reference; 300mg is 80%
- Reference point three: the guidance levelabout 400mg supplemental a day: the ceiling for a supplement dose
- The condition300mg elemental, not 300mg of bisglycinate, which is about 60mg
Our brand: the worked example on this page
Futuro Labs Magnesium Glycinate
- 22p a day
- 180 capsules, 2 capsules daily
- Lab tested
- Made in the UK
300mg elemental, on all three reference points: Futuro Labs Magnesium Glycinate on Amazon UK, 1500mg bisglycinate giving 300mg elemental at 80% NRV, under the guidance level, £19.99 for 90 days at 22p. Full label breakdown. The lifter's dose page is here; the NRV explained on the NRV guide.
The condition first, then three reference points against which any magnesium dose is read
Whether 300mg of a brand's magnesium glycinate is the right daily dose depends first on a condition the brand's name does not settle: whether the 300mg is elemental magnesium or the bisglycinate compound, since 300mg of the compound is about 60mg of magnesium, the 300mg-of-what teach, and the %NRV on the tub's nutrient line answers it, 80% for elemental and around 16% for compound. Assuming the honest reading, 300mg elemental, the dose is read against three reference points that answer three different questions. Reference point one, the reference nutrient intake: the UK's scientific figure for total magnesium from all sources, 300mg a day for adult men and 270mg for adult women, the amount judged sufficient for nearly everyone in the group, so a supplement delivering 300mg elemental provides a full RNI on its own, on top of whatever the diet supplies, which is why a lifter whose diet is already replete gains nothing from it and a lifter whose training diet runs light gains the shortfall, the diet audit deciding. Reference point two, the nutrient reference value: the labelling figure of 375mg, against which 300mg reads 80%, a convention rather than a target, and the number the label prints. Reference point three, the guidance level: the UK expert group's supplemental guidance of about 400mg a day, the ceiling for a supplement dose in healthy adults, under which 300mg sits with room to spare and above which the laxative effect and the guidance both argue against going. On all three, 300mg elemental is a sensible daily dose, a full RNI, most of the NRV and under the guidance level, the magnesium section's standing recommendation for a lifter whose audit says so.
The variables that move the answer, the compound reading's answer, and the dose filed
Three variables move the answer for an individual. The diet: a reader eating leafy greens, nuts, seeds, legumes and wholegrains daily may already meet the RNI from food, in which case 300mg supplemental is surplus excreted by healthy kidneys, harmless and pointless, and a reader on a training diet heavy in protein and light in those foods may fall short by a hundred milligrams or more, in which case 300mg closes the gap with margin. Sweat and training load: magnesium losses through sweat are real but modest, the sweat-loss page's finding that they raise needs slightly rather than dramatically, so a heavy trainer's requirement sits a little above the RNI and 300mg still covers it. The form and the gut: 300mg of bisglycinate's elemental magnesium is well absorbed and well tolerated, while 300mg elemental as oxide is less absorbed and more laxative, so the same number does different work in different salts, the bisglycinate reading being the one this page assumes. The compound reading's answer is different and short: 300mg of bisglycinate is about 60mg of elemental magnesium, 16% of the NRV, a fifth of the RNI, a token dose that neither harms nor closes any gap, and a reader whose tub declares 300mg at 16% NRV takes five capsules to reach the dose the front implied or buys a tub that states its elemental figure with its maths. The dose filed: 300mg elemental magnesium, as bisglycinate, once a day with a meal or split across two, is the right daily dose for a lifter whose diet audit finds a shortfall, sits well on all three reference points, and is exactly the worked example's specification, 1500mg bisglycinate giving 300mg elemental at 80% NRV over two capsules, under the guidance level, £19.99 for 90 days at 22p a day.
| The reference point | The figure | Where 300mg sits |
|---|---|---|
| The RNI | 300mg men, 270mg women, total intake | A full RNI from the supplement alone |
| The NRVOurs | 375mg, the labelling figure | 80% |
| The guidance level | About 400mg supplemental a day | Under it, with room |
| The diet | Greens, nuts, seeds, legumes, wholegrains | Replete diets need less; training diets often run light |
| The form | Bisglycinate well absorbed and tolerated; oxide less so | The same number does different work |
| 300mg of compound | About 60mg elemental, 16% NRV | A token: five capsules or another tub |
The verdict, right on three counts if it is elemental
Is 300mg of a brand's magnesium glycinate the right daily dose: yes on three reference points if the 300mg is elemental, a full reference nutrient intake for an adult, 80% of the labelling NRV and under the 400mg supplemental guidance level, in a form that is absorbed and tolerated, for a lifter whose diet audit finds a shortfall, and no if the 300mg is the bisglycinate compound, about 60mg of magnesium at 16% NRV, a token that the %NRV line reveals. The dose on all three counts: Futuro Labs Magnesium Glycinate, 1500mg bisglycinate giving 300mg elemental at 80% NRV over two capsules, £19.99 for 90 days at 22p a day.
What to check on the label
- Confirm elemental first: 80% NRV, not 16%.
- Read it against the RNI: a full adult intake from the supplement alone.
- Read it against the NRV: 80% of the labelling figure.
- Read it against the guidance level: under 400mg supplemental.
- Let the diet audit decide: surplus if replete, the gap if light.
Our brand
The worked example: Futuro Labs Magnesium Glycinate
Futuro Labs Magnesium Glycinate is the worked example for magnesium reviews because its label states every number a review needs: 1500mg magnesium bisglycinate at 20%, 300mg elemental, 80% NRV, 2 capsules a day, 180 capsules for £19.99, 22p a day, UK made, vegan HPMC shell, batch tested for lead, mercury, arsenic and cadmium, and only the register's own magnesium claims printed.
- Elemental magnesium per serving
- 300mg (80% NRV)
- Form
- magnesium bisglycinate 20%
- Serving
- 2 capsules a day
- Bottle
- 180 capsules, 90 days
- Price
- £19.99 (22p a day)
- Capsule
- vegetarian shell, vegan product
Questions people also ask
Is 300mg of magnesium a good daily dose?
As elemental magnesium, yes: it equals the adult reference nutrient intake of 300mg for men and exceeds the 270mg for women, reads 80% of the 375mg labelling NRV, and sits under the UK guidance level of about 400mg supplemental a day.
Is 300mg of magnesium glycinate the same as 300mg of magnesium?
Only if the label means elemental: 300mg of the bisglycinate compound is about 60mg of magnesium at 16% NRV, and the %NRV line on the tub tells you which the front means.
Do lifters need more than 300mg?
Rarely: sweat losses raise needs modestly rather than dramatically, so a heavy trainer's requirement sits a little above the RNI and 300mg still covers a shortfall, with the guidance level of about 400mg the ceiling.
What if my diet already contains plenty of magnesium?
Then 300mg supplemental is surplus excreted by healthy kidneys, harmless and pointless, which is why the diet audit, greens, nuts, seeds, legumes and wholegrains counted, decides whether the dose is needed.
Is 300mg safe to take every day?
Yes for healthy adults: it is under the UK guidance level of about 400mg supplemental, the laxative effect being the practical ceiling, with kidney disease, regular medication and pregnancy the three cases that ask a doctor first.
Sources
- Department of Health. Dietary Reference Values for Food Energy and Nutrients for the United Kingdom. Report on Health and Social Subjects 41, 1991 (magnesium RNI 300mg men, 270mg women).
- Retained Regulation (EU) No 1169/2011, Annex XIII: nutrient reference value for magnesium 375mg. https://www.legislation.gov.uk/eur/2011/1169/annex/XIII
- Expert Group on Vitamins and Minerals. Safe Upper Levels for Vitamins and Minerals. Food Standards Agency, 2003 (magnesium guidance level 400mg a day from supplements). https://cot.food.gov.uk/sites/default/files/vitmin2003.pdf
- Nielsen FH, Lukaski HC. Update on the relationship between magnesium and exercise. Magnesium Research 2006;19(3):180-189. PubMed record