The Best Supplements for Energy — and Why Iron Comes First
THE SHORT ANSWER
Nothing on this page is a stimulant. Persistent tiredness is usually a shortfall rather than a deficit of caffeine, and the four things most worth checking are iron, B12 and folate, magnesium and nitrate. Iron has the strongest evidence of the four — and one of the most misread. A 2003 trial found it reduced fatigue in women who were not anaemic,1 while a 2025 meta-analysis found it did not reliably improve exercise performance in the same population.2 Both are true, and the difference matters.*
What we would check, in order:
- Iron Complex — the first thing to test, and the one nobody should guess at
- 5-MTHF — active folate, for the methylation side of energy
- DiMagnesium Malate — magnesium for daytime rather than sleep
- Beet Nitric Oxide — the only one here aimed at performance rather than shortfall
- Alpha Lipoic Acid — cellular, and the most speculative of the five
011. Iron — and the finding most brands leave out
In 2003 a double-blind randomised trial gave 144 non-anaemic women with unexplained fatigue either 80 mg of elemental iron daily or placebo for four weeks. Iron reduced fatigue relative to placebo — and the benefit concentrated in the women with low ferritin, which was around half the group.1 A 2012 trial in menstruating women with low ferritin reached the same conclusion.3
Here is the part that usually gets left out. A 2025 systematic review and meta-analysis looked at exercise performance in women with non-anaemic iron deficiency and found no reliable improvement in time-to-exhaustion or time-trial results.2 So iron can make you feel less tired without making you objectively faster. Those are different outcomes, and a supplement page that blurs them is selling you something.
The practical rule: test ferritin before supplementing iron. Iron is not a nutrient to take speculatively — excess accumulates, and there is no efficient route to excrete it. We set out which marker to ask for in the marker most people guess at.
If you have tested and you are low, Iron Complex pairs bisglycinate with the cofactors, and Iron Bisglycinate 25 mg is the standalone.
022. B12 and folate
Fatigue from B12 or folate shortfall works through a different route: red cell formation and one-carbon metabolism rather than oxygen carriage. It is also the one where the form genuinely changes the outcome, because a substantial share of people convert folic acid to its active form inefficiently.
That is the entire reason we make 5-MTHF rather than folic acid, and we explained the biochemistry in why your body prefers active B vitamins. If you want the higher dose, there is 5 mg.
033. Magnesium — the daytime form
Magnesium is a cofactor in the reactions that produce ATP, which is why it shows up in energy conversations at all. But the form matters for when you take it: glycinate settles you, malate does not.
DiMagnesium Malate is the daytime one for that reason, and choosing by time of day sets out how to pick. If you want both in one bottle, Magnesium Complex combines them.
044. Nitrate — the performance one
Beetroot is the odd entry here because it is not correcting a shortfall. Dietary nitrate converts to nitric oxide and affects blood flow and the oxygen cost of exercise, which is a performance mechanism rather than a fatigue one.
It also has the strangest failure mode in the category: antibacterial mouthwash disrupts the oral bacteria that make the conversion possible, and can cancel the effect entirely. We wrote that up in the mouthwash that cancels them. Ours is here.
055. Alpha lipoic acid
ALA sits in mitochondrial energy metabolism and acts as an antioxidant. We are listing it last and calling it the most speculative of the five deliberately — the human evidence for ALA as a general energy supplement is thinner than for iron or B12, and we would rather say so than pad the list. Ours is here if you want it, and the letter that halves your dose explains why the R form matters.
06What we would do before any of this
Sleep, iron status and thyroid function explain more persistent fatigue than every supplement on this page combined, and two of those three need a blood test rather than a bottle. We made the broader argument in you can't supplement your way past the basics.
If you have covered those, the Daily Energy range is where to start.
07What we can actually show you
The evidence above is what it is — good for iron in low-ferritin women, weaker as you go down the list. What is not uncertain is what is in the bottle. Every lot is tested by an independent laboratory for identity, potency, heavy metals and microbials, and the certificate for the lot currently shipping publishes on the product page.
08Frequently asked questions
Should I just take iron if I am tired?
No. Test ferritin first. Iron accumulates and the body has no efficient way to shed an excess, so it is the one nutrient on this list where guessing carries real downside.
Can I be iron deficient without being anaemic?
Yes, and that is exactly the population the fatigue trials studied — women with normal haemoglobin but low ferritin.1,3 Haemoglobin alone can look fine while stores are depleted.
Will iron make me perform better in training?
Not reliably. The 2025 meta-analysis found no consistent improvement in time-to-exhaustion or time-trial performance in women with non-anaemic iron deficiency,2 even though fatigue trials show a benefit to how people feel.
Is folate the same as folic acid?
Not functionally. Folic acid requires conversion, and a meaningful share of people convert it inefficiently. 5-MTHF is already in the active form.
Which magnesium should I take for energy rather than sleep?
Malate. Glycinate is the calming one and is better placed in the evening.
Does mouthwash really cancel beetroot?
Antibacterial mouthwash disrupts the oral bacteria that reduce dietary nitrate to nitrite, which is the first step in the pathway. It is an odd interaction, and a real one.
09References
- Verdon F, Burnand B, Fallab Stubi CL, et al. Iron supplementation for unexplained fatigue in non-anaemic women: double blind randomised placebo controlled trial. BMJ. 2003;326(7399):1124. doi:10.1136/bmj.326.7399.1124
- Effect of iron supplementation on exercise performance of women with non-anemic iron deficiency or iron deficiency anaemia: a systematic review and meta-analysis. 2025.
- Vaucher P, Druais PL, Waldvogel S, Favrat B. Effect of iron supplementation on fatigue in nonanemic menstruating women with low ferritin: a randomized controlled trial. CMAJ. 2012;184(11):1247–1254.
- Waldvogel S, Pedrazzini B, Vaucher P, et al. Clinical evaluation of iron treatment efficiency among non-anemic but iron-deficient female blood donors: a randomized controlled trial. BMC Med. 2012;10:8.
- Brownlie T, Utermohlen V, Hinton PS, Giordano C, Haas JD. Marginal iron deficiency without anemia impairs aerobic adaptation among previously untrained women. Am J Clin Nutr. 2002;75(4):734–742.
- Haas JD, Brownlie T. Iron deficiency and reduced work capacity: a critical review of the research to determine a causal relationship. J Nutr. 2001;131(2S-2):676S–688S.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
