Several supplements have solid evidence behind them for reducing fatigue and supporting your body’s energy production, but the ones that will actually help you depend on what’s causing your low energy in the first place. A nutrient deficiency, chronic stress, and poor mitochondrial function each call for different solutions. Here’s what the evidence supports.
Iron: The Most Common Nutritional Cause of Fatigue
Every cell in your body needs oxygen to produce energy, and iron is the mineral that makes oxygen transport possible. It sits at the center of hemoglobin, the protein in red blood cells that carries oxygen from your lungs to your tissues. When iron stores drop, your cells get less oxygen, and the result is a kind of deep, whole-body tiredness that sleep doesn’t fix.
Low iron is one of the most common nutritional deficiencies worldwide, and fatigue is its hallmark symptom. Other signs include pale skin, dizziness, shortness of breath, and a fast heartbeat. The standard blood test measures ferritin, a protein that reflects your iron stores. Normal ferritin ranges are 15 to 205 ng/mL for women and 30 to 566 ng/mL for men, but many people with ferritin levels technically in the “normal” range but on the low end still feel fatigued.
If you suspect iron is the issue, get tested before supplementing. Too much iron causes its own problems, including fatigue, joint pain, and stomach pain. Iron supplements are best absorbed on an empty stomach with vitamin C, though taking them with food reduces the nausea some people experience. Premenopausal women, vegetarians, and frequent blood donors are at highest risk for deficiency.
Vitamin B12: Essential for Converting Food to Fuel
B12 plays a direct role in how your body turns food into usable energy. It acts as a helper molecule for enzymes involved in breaking down fats and amino acids, ultimately feeding those building blocks into your cells’ energy-producing machinery. Without enough B12, this process slows down, and fatigue is one of the earliest symptoms.
About 3.6% of adults have outright B12 deficiency, but insufficiency (levels that are low but not critically so) affects roughly 12.5% of all adults. Among older adults living in care facilities, up to 38% have suboptimal levels. The people most likely to be low include vegans, vegetarians, adults over 60 (whose stomachs absorb B12 less efficiently), and anyone taking acid-reducing medications long term.
If you are deficient, B12 supplements can start improving energy within a few days to a few weeks, with dissolving tablets and injections working faster than standard pills. If your B12 levels are already normal, however, extra B12 won’t give you a noticeable boost. This is a supplement that corrects a deficit rather than supercharging a system that’s already working fine.
Magnesium: The Mineral Behind ATP
Your body’s energy currency is a molecule called ATP, and magnesium is physically required to make it. Magnesium binds directly to ATP during its synthesis inside mitochondria, helping position the molecular components so the reaction can proceed. Without adequate magnesium, your cells literally produce less energy at the biochemical level.
Despite how critical this mineral is, many people fall short. Magnesium is found in nuts, seeds, leafy greens, and whole grains, foods that are underrepresented in many modern diets. Symptoms of low magnesium go beyond fatigue and include muscle cramps, poor sleep, and irritability, all of which compound the feeling of low energy.
Magnesium glycinate and magnesium citrate are the forms most commonly recommended for general supplementation because they’re well absorbed and easier on the stomach than magnesium oxide. If you’re also dealing with poor sleep, magnesium taken in the evening can pull double duty, since better sleep quality directly improves daytime energy.
Ashwagandha and Rhodiola: When Stress Is Draining You
If your fatigue feels less like a physical deficit and more like burnout, adaptogens may be worth considering. These are plant-derived compounds that help your body manage the hormonal fallout of chronic stress, particularly elevated cortisol, the stress hormone that leaves you feeling wired but exhausted.
Ashwagandha has the stronger evidence for cortisol reduction. Clinical trials show it significantly lowers cortisol levels, and a 90-day trial using 500 mg per day of a standardized root extract found meaningful improvements in anxiety, depression, sleep quality, and overall quality of life compared to placebo. The energy benefit here is indirect but real: when your stress response calms down, your body stops burning through resources at an unsustainable rate.
Rhodiola rosea works through a slightly different angle, targeting fatigue and emotional exhaustion more directly. In a six-week trial, participants taking either 340 mg or 680 mg daily of a standardized extract showed significant improvements in depressive symptoms, sleep disturbances, emotional regulation, and physical complaints tied to stress. The placebo group showed no such improvements. Rhodiola tends to feel more immediately energizing than ashwagandha, which works more gradually on the stress-recovery side.
CoQ10: Cellular Energy Production
Coenzyme Q10 is a compound your body makes naturally that plays a central role inside your mitochondria, the structures within every cell that generate energy. It works as an electron shuttle in the chain of reactions that ultimately produces ATP. Your body’s production of CoQ10 declines with age, which is one reason cellular energy output drops as you get older.
Most CoQ10 research has focused on heart failure, cardiovascular health, and specific disease states, where doses of 100 to 300 mg per day have shown benefits over treatment periods of several months to years. For general energy support, the evidence is less dramatic but physiologically sound: if your CoQ10 levels are low (common in people over 40, those on statin medications, or anyone with chronic fatigue), supplementation restores a key bottleneck in energy production. The ubiquinol form is better absorbed than ubiquinone, especially for older adults. Doses in the range of 100 to 200 mg daily are typical for general use, and CoQ10 has a strong safety profile even at much higher amounts.
Creatine: Not Just for Muscles
Creatine is best known in the fitness world, but its core function is energy recycling, and that happens in your brain as much as in your muscles. About two-thirds of the creatine in your cells exists in a phosphorylated form that acts as a rapid energy buffer. When a cell burns through its ATP, creatine donates a phosphate group to rebuild it almost instantly. This system is especially active in tissues with high energy demands: skeletal muscle, the heart, and the brain.
Emerging research shows creatine supplementation can benefit cognitive function and mental energy. It’s present in synaptic vesicles (the packets neurons use to communicate) and appears to stimulate mitochondrial activity in brain cells. An eight-week trial found that 5 grams of creatine daily significantly improved depression scores compared to placebo, suggesting meaningful effects on brain energy metabolism and mood. Creatine also influences levels of several neurotransmitters and signaling molecules tied to mood and inflammation.
Creatine monohydrate is the most studied and least expensive form. It’s one of the few supplements with a large enough body of evidence to say confidently that it works for most people, not just those with a deficiency.
How to Choose the Right One
The best supplement for your energy depends on the underlying cause. If your fatigue came on gradually and you have risk factors for nutrient deficiency (restrictive diet, heavy periods, age over 60, chronic stress), start with bloodwork. Testing iron, ferritin, B12, and magnesium can identify whether a simple deficiency is behind your symptoms, and correcting a deficiency produces the most dramatic results.
If your labs look fine but you’re dealing with chronic stress and poor sleep, ashwagandha or rhodiola may address the actual bottleneck. If you’re over 40 or on statins and notice a general decline in stamina, CoQ10 targets a known age-related change. And creatine is a reasonable option for almost anyone looking to support both physical and mental energy, regardless of deficiency status.
Timelines matter for setting expectations. B12 can produce noticeable changes within days to weeks if you’re deficient. Iron repletion typically takes longer, often one to three months before ferritin stores fully rebuild. Adaptogens generally need four to eight weeks of consistent use before the effects become clear. CoQ10 and creatine both build up gradually, with most people noticing changes over several weeks of daily use.