Vitamins and Supplements for Fatigue: What Might Help and What to Know First

Which nutrients are most closely linked to fatigue?

Several nutrients play a direct role in how cells produce and use energy. When levels drop too low, tiredness is often one of the first signs.

Iron is essential for carrying oxygen in the blood. Iron-deficiency anemia is one of the most common correctable causes of fatigue, particularly in people who menstruate, are pregnant, or eat little red meat 1Ref 1Leung AKC, Lam JM, Wong AHC, Hon KL, Li X (2024).Iron Deficiency Anemia: An Updated Review.Iron deficiency as a common correctable cause of fatigue; risks of iron supplementation without confirmed deficiency.

Vitamin B12 supports nerve function and red blood cell production. Deficiency causes deep, persistent tiredness along with brain fog, tingling, and sometimes mood changes. It is more common in people on vegan or vegetarian diets and in older adults, whose stomachs absorb it less efficiently 2Ref 2Obeid R, Andrès E, Češka R, et al. (2024).Diagnosis, Treatment and Long-Term Management of Vitamin B12 Deficiency in Adults: A Delphi Expert Consensus.B12 deficiency causes fatigue, neurological symptoms, and is more common in vegans and older adults; supplementing normal B12 does not boost energy.

Vitamin D has receptors throughout the body, including muscle tissue. Low levels are common — particularly in people with limited sun exposure or darker skin tone — and are associated with fatigue and muscle weakness 3Ref 3Di Molfetta IV, Bordoni L, Gabbianelli R, Sagratini G, Alessandroni L (2024).Vitamin D and Its Role on the Fatigue Mitigation: A Narrative Review.Vitamin D deficiency is associated with fatigue and muscle weakness; correcting true deficiency can reduce fatigue.

Folate (vitamin B9) works alongside B12 in red blood cell production. Deficiency can cause anemia and fatigue, though it is less common where flour is routinely fortified.

Magnesium is involved in hundreds of body processes including energy metabolism. Obvious deficiency is uncommon, but low intake can contribute to fatigue and muscle cramps.

Other B vitamins (B1, B2, B3, B5, B6) are involved in energy production; deficiencies — while less common in people eating varied diets — can affect energy.

Why does testing before supplementing matter?

The supplement aisle is full of products marketed for energy, but most have limited evidence for people who are not actually deficient. Taking extra B12 when your B12 is already normal, for example, is unlikely to boost your energy 2Ref 2Obeid R, Andrès E, Češka R, et al. (2024).Diagnosis, Treatment and Long-Term Management of Vitamin B12 Deficiency in Adults: A Delphi Expert Consensus.B12 deficiency causes fatigue, neurological symptoms, and is more common in vegans and older adults; supplementing normal B12 does not boost energy.

More importantly, some supplements can cause harm at high doses. Iron supplementation in someone without iron-deficiency anemia can cause gastrointestinal side effects and, over time, iron overload 1Ref 1Leung AKC, Lam JM, Wong AHC, Hon KL, Li X (2024).Iron Deficiency Anemia: An Updated Review.Iron deficiency as a common correctable cause of fatigue; risks of iron supplementation without confirmed deficiency. Fat-soluble vitamins like vitamin D accumulate in the body, and very high doses can reach toxic levels 3Ref 3Di Molfetta IV, Bordoni L, Gabbianelli R, Sagratini G, Alessandroni L (2024).Vitamin D and Its Role on the Fatigue Mitigation: A Narrative Review.Vitamin D deficiency is associated with fatigue and muscle weakness; correcting true deficiency can reduce fatigue.

A basic blood test — ordered by a clinician — checks iron, ferritin (stored iron), B12, vitamin D, and other markers. That result tells you and your clinician exactly where to focus, rather than guessing.

What about general energy supplements?

Products marketed for energy often contain B-vitamin complexes, adaptogens (such as ashwagandha or ginseng), or coenzyme Q10. For most people eating a reasonably varied diet, these provide modest benefit at best. B vitamins are excreted when already sufficient, and evidence for adaptogens in the general population is mixed and often based on small studies.

Caffeine can boost alertness short-term but does not address underlying fatigue — and taken too late in the day it can disrupt sleep, making tiredness worse the next day.

If your fatigue is severe, persistent, or worsening, it is worth understanding the cause rather than supplementing around it. Fatigue can have many drivers — thyroid problems, anemia, sleep disorders, mental health conditions — that supplements will not address.

What is a reasonable first step?

If you feel generally well and are mostly looking for a modest energy boost, a daily multivitamin that meets basic recommended daily values is low-risk and covers common gaps. Prioritizing sleep (7–9 hours for most adults is the consensus target 4Ref 4Watson NF, Badr MS, Belenky G, et al. (2015).Recommended Amount of Sleep for a Healthy Adult: A Joint Consensus Statement of the American Academy of Sleep Medicine and Sleep Research Society.7–9 hours of sleep per night as the consensus recommendation for healthy adults), hydration, and regular movement will often do more than any individual supplement.

If your tiredness is persistent, getting in the way of daily life, or accompanied by other symptoms — shortness of breath, heart racing, coldness in the hands, brain fog, mood changes, or unexplained weight changes — a clinician visit and blood work is the more useful next step.

Which factors raise your risk of a nutrient deficiency?

Certain groups are at meaningfully higher risk for specific deficiencies:

• Menstruation and pregnancy. Monthly blood loss raises iron needs. Pregnancy raises iron, folate, and B12 needs significantly. Fatigue in pregnancy warrants specific guidance from a prenatal clinician.
• Vegan or vegetarian diet. B12 is found almost exclusively in animal products; vegans almost always need supplementation 2Ref 2Obeid R, Andrès E, Češka R, et al. (2024).Diagnosis, Treatment and Long-Term Management of Vitamin B12 Deficiency in Adults: A Delphi Expert Consensus.B12 deficiency causes fatigue, neurological symptoms, and is more common in vegans and older adults; supplementing normal B12 does not boost energy. Iron from plant sources is absorbed less efficiently.
• Older age. B12 absorption declines with age due to changes in stomach acid. Vitamin D synthesis from sunlight also declines.
• Chronic conditions. Kidney disease, inflammatory bowel disease, and celiac disease can impair absorption of multiple nutrients.
• Certain medications. Metformin can deplete B12 over time. Proton pump inhibitors reduce B12 and magnesium absorption.