Energy

The best supplements for energy start with a blood test.

Most lasting tiredness has a cause you can look for. Here is where to look first.

By the Umbral teamUpdated October 3, 202610 min read29 studies cited

Quick answer

The best supplements for energy correct a shortfall a blood test can find. Iron, taken only after a ferritin test, cut tiredness by 48% versus 29% on placebo in women with low stores. Vitamin D and B12 help only when a test shows you are low. With normal results, Panax ginseng eased everyday tiredness modestly across 19 trials.

Key takeaways

Test before you take: ferritin and a CBC decide iron, 25(OH)D decides vitamin D, and serum B12 decides B12.
In non-anemic menstruating women with ferritin under 50 µg/L, iron cut fatigue 47.7% versus 28.8% on placebo over 12 weeks.
Late caffeine costs about 45 minutes of sleep: a 107 mg coffee needs at least 8.8 hours before bed.
Correcting low iron is one of the most wearable-visible changes there is, since deficiency raises resting heart rate and lowers VO₂ max.

In this guide

What is the best supplement for tiredness?
Why are you tired? What to rule out first
Which blood tests should you get before taking supplements for tiredness?
Which supplements help tiredness when your blood work is normal?
Which energy supplement is best for you?
Do B vitamins give you energy?
How do you use caffeine without losing sleep?
Will your wearable show the difference?
Frequently asked questions
References

What is the best supplement for tiredness?

The best supplement for tiredness is the one that corrects a shortfall you actually have. IronStrong, vitamin DModerate and B12Moderate rank first for that reason, and each comes only after a blood test: iron only after a ferritin test, never blind. With normal results, the evidence for everything else is modest.

Ranked for tiredness: shortfalls first, then direct evidence on fatigue
Supplement · Evidence	Best for	What studies found	Typical dose	On your wearable
Iron (ferritin-gated) Strong	Low ferritin, confirmed by a blood test	Tiredness fell 48% vs 29% on placebo in women with low stores.	60–100 mg every other day	Likely visible
Vitamin D (test-gated) Moderate	A low 25(OH)D result	Eases tiredness and weakness only when you are deficient; retest at 3 months.	1,000–2,000 IU a day	Below wearable noise
Vitamin B12 (test-gated) Moderate	Vegans, over 50, metformin or acid blockers	One meta-analysis: no effect on tiredness when levels are already normal.	500–1,000 µg a day if low	Below wearable noise
Panax ginseng Moderate	Everyday tiredness, normal blood work	Modest help across 19 trials; the overall pooled result was not significant.	1–2 g a day, mornings	Below wearable noise
CoQ10 / ubiquinol Moderate	Adults over 40 or on statins	Reduced fatigue across 13 trials, more at higher doses.	100–300 mg with a fatty meal	Below wearable noise
Creatine monohydrate Strong	Training hard or running short on sleep	Best-studied performance supplement; one large dose partly restored thinking during 21 hours awake.	3–5 g a day	Below wearable noise
Caffeine Strong	Training sessions, with an early cut-off	Improves performance in every modality tested; late doses cost about 45 minutes of sleep.	3–6 mg per kg (1.4–2.7 per lb)	Likely visible

Why are you tired? What to rule out first

Before you buy anything, rule out five things in this order: short or broken sleep, low stores of ironStrong, low vitamin DModerate, low B12Moderate, and more training than you recover from. Three of the five are blood tests. None is settled by guessing, and no capsule fixes the first or the last.

Sleep. No supplement outranks a full night; see our guide to supplements for sleep.
Iron stores. You can be low without being anemic; take iron only after a ferritin test and CBC, never blind.
Vitamin D. It eases tiredness only if you are deficient, which a 25(OH)D test shows.
B12. Check it if you are vegan, over 50, or on metformin or stomach-acid medication, and take it only after a serum B12 test.
Training load. More hard sessions than you recover from? Fix the plan first; see supplements for training.

Which blood tests should you get before taking supplements for tiredness?

Ask for three: ferritin with a complete blood count (CBC), which decides ironStrong; 25(OH)D, which decides vitamin DModerate; and serum B12, sometimes with MMA, which decides B12Moderate. Each result tells you whether there is anything to correct. Without them you are guessing, and with iron a wrong guess can do harm.

The three blood tests to get before supplements for tiredness
Test	Supplement it decides	Who should ask for it
Ferritin + CBC	Iron. Hemochromatosis affects about 1 in 250 people, which is why iron is never taken blind.	Menstruating women, the group in the trial; endurance athletes; vegetarians
25(OH)D	Vitamin D: 1,000–2,000 IU a day if low, under the 4,000 IU upper limit; retest in 3 months	People with little sun exposure, or darker skin at high latitude
Serum B12 (± MMA)	B12: 500–1,000 µg a day if low	Vegans, adults over 50, people on metformin or stomach-acid medication

Iron (ferritin-gated)

Strong

Bisglycinate, alternate-day

For anyone whose ferritin comes back low, even without anemia. Menstruating women with ferritin under 50 µg/L took iron for 12 weeks: tiredness fell 47.7%, against 28.8% on placebo. A second trial agreed, mainly at ferritin of 50 µg/L or less.

Low iron lowers VO₂ max and raises resting heart rate, so correcting it is the change your wearable is most likely to show.

Dose: 60–100 mg elemental every other day + vitamin C (trial: 80 mg/day × 12 wk; alternate-day per absorption studies)
Timing: Away from coffee, tea and calcium

⚑ Blood test first: Ferritin + CBC

Watch out for

· NEVER without ferritin + CBC — hemochromatosis affects ~1/250; excess iron is pro-oxidant.

Likely visibleSee the full evidence →

Vitamin D (test-gated)

Moderate

For anyone whose 25(OH)D comes back low: it eases tiredness and muscle weakness when you are deficient and does essentially nothing when you are not. The change is usually too small for a wearable to see, so judge it on the 3-month retest.

Dose: 1,000–2,000 IU/day (UL 4,000)
Timing: With food; retest in 3 months

⚑ Blood test first: 25(OH)D

Watch out for

· Hypercalcemia at chronic high doses; thiazide interaction.

Below wearable noiseSee the full evidence →

Which supplements help tiredness when your blood work is normal?

When your ferritin, 25(OH)D and B12 tests come back normal, the evidence gets thinner. Panax ginsengModerate has the most data on everyday tiredness, CoQ10Moderate reduced fatigue in trials, and Creatine monohydrateStrong helps you perform on short sleep. Rhodiola roseaEmerging and CordycepsEmerging are still emerging, and L-carnitineModerate works on recovery, not performance.

Panax ginseng

Moderate

Panax ginseng C.A. Meyer root extract, 1–2 g/day of a 20% ethanol extract, or Korean Red Ginseng 2–3 g/day

For everyday tiredness with no medical cause. Across 19 trials the overall result was not significant, but it held for general, non-disease fatigue, and in a 90-person trial 1–2 g a day beat placebo within 4 weeks. Small effects.

Morning and midday only: insomnia is a documented side effect, so this one can worsen your sleep numbers.

Dose: 1–2 g/day of standardised extract; 3 g/day of Korean Red Ginseng failed to beat placebo on fatigue in one trial
Timing: Morning and midday with food. Never in the evening — insomnia is a documented adverse effect

Watch out for

· Insomnia, hypertension, diarrhoea and skin rash are the common adverse effects; this one can worsen your sleep metrics.
· 'Ginseng abuse syndrome' reported at 7–15 g/day, resolving on reduction to 1.7 g/day.
· Avoid in pregnancy and lactation — teratogenicity at high ginsenoside doses in animals.

Below wearable noiseSee the full evidence →

CoQ10 / ubiquinol

Moderate

Ubiquinol softgel

For adults over 40 and people on statins, which block its production. Across 13 trials it reduced fatigue, more at higher doses, and it lowers blood pressure a little. Usually below what a wearable can see.

Dose: 100–300 mg
Timing: With a fatty meal

Watch out for

· May reduce warfarin effect.

Below wearable noiseSee the full evidence →

Creatine monohydrate

Strong

Powder

Creatine doesn't remove tiredness; it softens its cost. In a 15-person 2024 trial, a single large dose partly restored thinking during 21 hours awake, an emerging finding. It won't raise your HRV; it shows in what you can do after a short night.

Dose: 3–5 g/day
Timing: Any time; consistency matters

Watch out for

· Raises lab creatinine harmlessly; hydrate.

Below wearable noiseSee the full evidence →

Rhodiola: less fatigue and perceived exertion in mixed-quality trials, with the best data in burnout. Mildly stimulating, so mornings only.
Cordyceps: 12 weeks of Cs-4 raised the metabolic threshold 10.5% in adults aged 50 to 75, but VO₂ max did not change.
L-carnitine: lowered a muscle-damage marker and next-day soreness across 14 trials. A recovery effect, not a performance one.

Which energy supplement is best for you?

Start from what is most likely behind your tiredness, not from the shelf. If a blood test finds a shortfall, correct that and add nothing else. If your blood work is normal, match the supplement to your situation and start one at a time, for the weeks its trials needed.

Which energy supplement fits your situation
If this sounds like you	Start with	Why
You menstruate and feel tired most days	Ferritin + CBC first; ironStrong only if low	Tiredness fell 48% vs 29% on placebo with ferritin under 50 µg/L
Vegan, over 50, or on metformin or acid medication	Serum B12 first; B12Moderate only if low	No benefit when levels are normal
You get little sun	25(OH)D first; vitamin DModerate only if low	Helps only when you are deficient
Normal blood work, everyday tiredness	Panax ginsengModerate, mornings	Modest help across 19 trials
Over 40, or on a statin	CoQ10Moderate	Reduced fatigue across 13 trials
You train hard or sleep short	Creatine monohydrateStrong	Softens the cost of poor recovery
You lean on coffee or pre-workouts	An earlier caffeineStrong cut-off	Late doses cost about 45 minutes of sleep

Do B vitamins give you energy?

Only if you were low to begin with. A meta-analysis found that B12Moderate had no effect on tiredness or thinking when levels were already normal. If you are vegan, over 50, or take metformin or stomach-acid medication, ask for a serum B12 test; if it comes back low, correcting it is the point.

Vitamin B12 (test-gated)

Moderate

Methyl- or cyanocobalamin

Also worth testing after bariatric surgery. If you are deficient, correcting it matters; if not, it is inert. Either way, the change is too small for a wearable to see.

Dose: 500–1,000 µg/day if low
Timing: Any time

⚑ Blood test first: Serum B12 (± MMA)

Watch out for

· Extremely safe.

Below wearable noiseSee the full evidence →

How do you use caffeine without losing sleep?

Keep the dose at 3–6 mg per kg of body weight (1.4–2.7 mg per pound) and move the last one earlier. In a 24-study meta-analysis, a 107 mg coffee needed at least 8.8 hours before bed and a 217 mg pre-workout at least 13.2 hours. Taken too late, CaffeineStrong cost about 45 minutes of total sleep.

Caffeine

Strong

Anhydrous caffeine capsules for dose precision, or coffee (~95 mg per 240 mL cup); caffeinated gum absorbs faster and needs less lead time

The energy supplement nearly everyone already takes. It improves performance in every kind of exercise tested; 9 mg/kg (about 4 mg per pound) adds side effects, not performance. Late doses cost 45 minutes of total sleep and 11 of deep sleep, and add 9 minutes to falling asleep, more if you metabolize it slowly.

Dose: 3–6 mg/kg (1.4–2.7 mg/lb) body mass; as little as 2 mg/kg (0.91 mg/lb) is ergogenic for some, and 9 mg/kg (4.1 mg/lb) adds side effects without adding performance
Timing: 60 min before exercise (less for gum). The cut-off matters more than the dose: a 107 mg coffee needs ≥8.8 h before bedtime and a 217 mg pre-workout ≥13.2 h — meaning a pre-workout at 6 pm is still costing sleep at midnight.

Watch out for

· Sleep disruption is the dominant documented cost: −45.3 min total sleep time, −7.0% sleep efficiency, −11.4 min deep sleep
· Anxiety, jitteriness, tachycardia and palpitations, strongly dose-dependent and modulated by ADORA2A genotype
· Acutely raises blood pressure and delays post-exercise heart rate and blood pressure recovery

Likely visibleSee the full evidence →

01Find your dose. At 3 mg/kg (1.4 mg per pound), a 154 lb (70 kg) adult lands near 210 mg, about two 95 mg cups of coffee.
02Count back from bedtime. For 11 pm: last coffee by 2 pm, any pre-workout by 9:45 am.
03Check your own data. Give the new cut-off a week of nights before judging your total sleep.

Will your wearable show the difference?

Sometimes. Correcting low ironStrong is one of the most wearable-visible changes there is, because deficiency raises resting heart rate and lowers VO₂ max. Moving your caffeineStrong cut-off can show in total sleep. Most other energy supplements have real effects that usually sit below the night-to-night noise a wearable records.

Plausibly visible in your own trend: iron (only after a ferritin test, never blind), through resting heart rate and VO₂ max; and caffeine, whose 45-minute sleep cost is about one ordinary night-to-night swing, so a week shows it better than a night. If HRV dips after late caffeine, the evidence points to the lost sleep.
Real but usually below the noise: vitamin DModerate and B12Moderate (each after its blood test), creatineStrong, Panax ginsengModerate, CoQ10Moderate, rhodiolaEmerging, cordycepsEmerging and L-carnitineModerate. Ginseng is the exception that can show, in the wrong direction, if taken late.

So measure instead of guessing. Connect the wearable you already own and let it learn your band, your normal range for resting heart rate, HRV and sleep. Beyond energy, see which supplements you actually need. Then:

01Get the blood tests and correct any shortfall they find.
02Start one supplement at its trial dose; one change at a time is the only way to tell what worked.
03Measure it against your band and read the result as association, not causation.

Frequently asked questions

Can low iron make you tired without anemia?

Yes. The CMAJ trial enrolled menstruating women who were not anemic but had ferritin under 50 µg/L. Over 12 weeks, iron cut their fatigue scores by 47.7%, against 28.8% on placebo. That is why ferritin belongs next to the CBC, and why iron comes only after a ferritin test, never blind.

How long does iron take to help with tiredness?

Give it about 12 weeks, the length of the trial that showed the benefit: 80 mg a day cut tiredness 47.7% versus 28.8% on placebo. Absorption studies favor alternate-day dosing, away from coffee, tea and calcium. Ask the clinician who ordered your ferritin test when to recheck it.

Should I take vitamin D every day?

Only if a 25(OH)D test shows you are low. Then the usual dose is 1,000 to 2,000 IU a day with food, under the 4,000 IU upper limit, with a retest in 3 months. Chronic high doses can raise blood calcium, and at normal levels extra vitamin D does essentially nothing for tiredness.

Does creatine give you energy?

Not the way caffeine does. Creatine helps cells regenerate ATP faster, in muscle and brain, and is the best-studied performance supplement there is. In one small 2024 trial, a single large dose partly restored thinking during 21 hours without sleep. Take 3 to 5 g a day; consistency matters more than timing.

Is it safe to take ginseng every day?

Trials used 1 to 2 g a day of standardized Panax ginseng for weeks. Insomnia, raised blood pressure, diarrhea and rash are the common side effects, so take it in the morning or at midday, never in the evening. A ginseng abuse syndrome was reported at 7 to 15 g a day. Avoid it in pregnancy.

Are energy drinks and pre-workouts just caffeine?

For your sleep, count them as caffeine first. The meta-analysis behind the sleep numbers used a 217 mg pre-workout, which needed at least 13.2 hours before bed, so one at 6 pm is still costing sleep at midnight. Check the milligrams on the label, add your coffee, and keep the day within 3 to 6 mg/kg (1.4 to 2.7 mg per pound).

Find out which of these move your numbers.

A guide can rank the evidence; only your own data can say what works for you. Umbral learns your band (your normal range) for sleep, HRV and recovery, recommends the supplements with evidence for what it sees, and measures each one against you. Results read as association, not causation.

Find out which supplements you need

Just connect the wearable you already own: WHOOP, Oura, Garmin, Fitbit and more. Nothing new to buy, no blood draw to start.

References

Every number in this guide comes from these studies: the same evidence catalogue that grades recommendations inside Umbral.

Rhodiola rosea

Rhodiola rosea for physical and mental fatigue: a systematic review
BMC Complementary and Alternative Medicine · 2012 · systematic review

Cordyceps

Effect of Cs-4 (Cordyceps sinensis) on Exercise Performance in Healthy Older Subjects: A Double-Blind, Placebo-Controlled Trial
The Journal of Alternative and Complementary Medicine · 2010 · rct · 1 trials · n = 20
Current Evidence of Ergogenic and Post-Exercise Recovery Effects of Dietary Supplementation with Cordyceps militaris in Humans — A Narrative Review
Nutrients · 2026 · systematic review · 5 trials · n = 321
Acute Cordyceps militaris supplementation and elevated resting oxygen uptake with faster reaction times: A randomized crossover trial
PLOS ONE · 2026 · crossover · 1 trials · n = 12

L-carnitine

Effects of L-carnitine supplementation on markers of exercise-induced muscle damage in healthy adults: A systematic review and meta-analysis of randomized controlled trials
Advanced Exercise and Health Science · 2025 · meta-analysis · 14 trials · n = 284
L-Carnitine Tartrate Supplementation for 5 Weeks Improves Exercise Recovery in Men and Women: A Randomized, Double-Blind, Placebo-Controlled Trial
Nutrients · 2021 · rct · 1 trials · n = 80
L-Carnitine treatment reduces severity of physical and mental fatigue and increases cognitive functions in centenarians: a randomized and controlled clinical trial
The American Journal of Clinical Nutrition · 2007 · rct · 1 trials · n = 66
Intestinal microbiota metabolism of L-carnitine, a nutrient in red meat, promotes atherosclerosis
Nature Medicine · 2013 · cohort · 1 trials · n = 2,595

Umbral is a wellness product, not a medical device. It does not diagnose, treat, cure or prevent any disease. Supplement information is educational; talk to a clinician before starting anything, especially if you are pregnant, under 18, managing a condition or taking medication. These statements have not been evaluated by the Food and Drug Administration.

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