Vitamin B5 for Energy, Fatigue and Fat Metabolism

Table of Contents

1. How B5 Turns Food Into Fuel
2. Building Fat, and Burning Ketones
3. What Real B5 Deficiency Did to Energy
4. Does Extra B5 Boost Energy If You Already Have Enough?
5. Is B5 a Fat Burner?
6. Three Claims, Three Evidence Levels
7. Tired All the Time? What to Check First
8. B5-Rich Whole Foods for Steady Energy
9. Safety and Sensible Doses
10. Key Research Papers
11. Connections
12. Featured Videos

How B5 Turns Food Into Fuel

Think of your cells as a power station with one main furnace: the Krebs cycle (also called the citric acid or TCA cycle) inside the mitochondria. Fuel cannot be shovelled into that furnace raw. It first has to be cut into a standard two-carbon "briquette" called an acetyl group, and that briquette has to be carried in on a handle. The handle is coenzyme A (CoA). Attached together they make acetyl-CoA, the single gateway molecule that both carbohydrate and fat must pass through.

Coenzyme A is assembled inside the cell in five steps, and the starting material is pantothenic acid — vitamin B5. Humans cannot make B5, so every molecule of CoA you own was built from B5 you ate (biochemistry review: Leonardi and colleagues, 2005). CoA takes part in more than 100 different reactions across the metabolism of fats, carbohydrates, proteins and alcohol (review: Czumaj and colleagues, 2020). For the step-by-step assembly line, see our Coenzyme A Synthesis page.

From carbohydrate

Glucose is first split in the cell fluid into two molecules of pyruvate. Pyruvate then crosses into the mitochondria, where a large enzyme complex called pyruvate dehydrogenase snips off one carbon (breathed out as carbon dioxide) and clips the remaining two-carbon piece onto CoA. No CoA, no acetyl-CoA — the sugar's energy stays stuck at pyruvate. Several B vitamins work side by side in that one enzyme: B1 (thiamine), B2 (riboflavin), B3 (niacin) and B5 (as CoA), which is one reason B vitamins are usually discussed as a team.

From fat

A fatty acid has to be "switched on" before it can be burned: it is first attached to CoA to become an acyl-CoA. It is then carried into the mitochondria (with help from carnitine) and broken down by beta-oxidation, a repeating cycle that chops two carbons off at a time — and every chop needs a fresh CoA to receive the piece. A long fatty acid therefore consumes CoA again and again on its way to becoming a string of acetyl-CoA molecules.

Inside the furnace

Acetyl-CoA hands its two carbons to the Krebs cycle, which strips out their energy as electrons that drive ATP production. CoA shows up again partway round the cycle as succinyl-CoA, so the cycle itself depends on it. In short, coenzyme A sits at every entrance to the furnace and at one point inside it.

The low-B5 branch is the honest version of "B5 gives you energy": when coenzyme A runs short, every fuel route slows at once, so the result is a whole-body, hard-to-pin-down tiredness rather than one dramatic symptom. The right-hand column is the other half of the story, covered below: topping up a tank that is already full does not make the engine bigger.

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Building Fat, and Burning Ketones

B5 is not only about burning fuel; it is also needed to store it. When you eat more than you need, the body builds new fatty acids on a large enzyme called fatty acid synthase. At its heart is the acyl carrier protein, which swings the growing fat chain from station to station on a flexible arm called 4'-phosphopantetheine — a piece cut from CoA, and therefore made from B5 (review: Leonardi and colleagues, 2005). The raw material for that chain is malonyl-CoA, another CoA compound.

So B5 sits on both sides of the ledger: it is needed to build fat and to burn it. That alone is a good reason to be wary of anyone selling it as a one-way "fat burner" — the vitamin is a tool the body uses in whichever direction your overall energy balance points.

Ketones

During fasting, very-low-carbohydrate eating or long exercise, the liver turns some of the acetyl-CoA from fat into ketone bodies (acetoacetate and beta-hydroxybutyrate), passing through a CoA compound called HMG-CoA on the way. Ketones travel in the blood to the brain, heart and muscles, which turn them back into acetyl-CoA — a step that borrows CoA from succinyl-CoA. Ketone production is a normal, useful adaptation that lets the brain run on fat-derived fuel when glucose is scarce; it is not a sign that fat is being "wasted". This point matters when we look at the weight-loss claim further down. For the practical side, see our Ketogenic Diet and Fasting pages.

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What Real B5 Deficiency Did to Energy

Because B5 is in nearly every food, naturally occurring deficiency is almost never seen on its own. What we know about it comes mainly from a small series of experiments at the University of Iowa in the 1950s, in which volunteers were deliberately made deficient — a pantothenate-free diet, in some groups combined with omega-methyl pantothenic acid, a look-alike molecule that blocks B5 from being used (Bean and colleagues, 1955; Hodges and colleagues, 1958 and 1959). Evidence tier: small controlled human depletion studies — a handful of men each, but direct human evidence.

The 1958 report described a cluster of changes that appeared over weeks: fatigue, apathy and a general feeling of being unwell (malaise), stomach and bowel upset, personality changes, and, less regularly, a faster heart rate and unstable blood pressure. Several men developed tingling or burning in the hands and feet. In other words, fatigue was genuinely the first and most common complaint — the common claim that B5 deficiency causes tiredness is correct.

Two corrections to how these experiments are often retold. First, the blood-pressure problem the papers describe is a tendency for pressure to drop on standing up (postural or orthostatic hypotension), not orthostatic hypertension. Second, burning feet is a real feature of B5 deficiency, but it is not unique to it: diabetes, alcohol, B12 or B1 shortage, kidney disease and several medicines cause burning feet far more often. Our Burning Feet and Neuropathy page covers that in detail, and Human Deficiency Experiments tells the full story of the Iowa studies.

A later diet study gives a sense of the timescale. Fry and colleagues (1976) fed adult men a low-B5 diet for 63 days. Their urinary pantothenic acid fell from an average of 3.05 mg a day to 0.79 mg a day, while a comparison group given 10 mg a day stayed replete. Blood levels responded more sluggishly than urine. The study reports measurable shifts in urine, blood and nitrogen balance rather than the striking illness seen when the blocking drug was used — a reminder of how hard true B5 deficiency is to produce with food alone.

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Does Extra B5 Boost Energy If You Already Have Enough?

This is the question that really matters for someone standing in a supplement aisle. The logic sounds tight: B5 makes CoA, CoA runs energy metabolism, so more B5 should mean more energy. The trouble is that cells do not build CoA in proportion to how much B5 is available. The first step of CoA assembly (the enzyme pantothenate kinase) is tightly regulated by feedback from CoA itself, so once the cell has enough, extra B5 mostly passes out in the urine (review: Leonardi and colleagues, 2005). An analogy: a factory with plenty of raw material in the yard does not run faster because a second truck of the same material arrives.

The athlete trials

Athletes are the ideal test group: if extra B5 improved fuel use anywhere, it should show in a hard endurance effort, where fat and carbohydrate burning are measured precisely.

• Webster (1998) — a randomised, double-blind, placebo-controlled crossover trial in 6 highly trained cyclists. For 7 days before each test they took either a placebo or 1 g of allithiamin (a B1 derivative) plus 1.8 g of a pantethine/pantothenic acid compound. They then rode 50 km at a steady pace followed by a 2000-m time trial. There were no significant differences in heart rate, oxygen use, blood lactate, glucose, fatty acids or perceived effort. The time trial took 178.2 seconds on placebo and 170.7 seconds on the supplement, a gap that was not statistically meaningful (P=0.58). Tier: small RCT, negative.
• Whitfield and colleagues (2021) — the most direct test so far. 14 trained male cyclists were matched into a control group or a group taking 6 g of pantothenic acid a day for 16 weeks — more than a thousand times the 5 mg Adequate Intake. Muscle biopsies were taken repeatedly. Muscle coenzyme A and acetyl-CoA did not rise, and exercise performance did not change. Tier: small controlled trial with tissue measurements, negative.

The second trial is especially telling because it measured the very molecule the theory relies on. Four months of huge doses did not raise CoA inside muscle at all, which fits the feedback-control picture above.

B-complex products and fatigue

Studies of mixed vitamin products are sometimes quoted as evidence for B5. In one randomised, double-blind, placebo-controlled trial, 215 working men aged 30 to 55 took a high-dose B-complex plus vitamin C and minerals, or a placebo, for 33 days; the supplement group rated themselves as less stressed, more vigorous and less mentally tired, and did better on one mental arithmetic task (Kennedy and colleagues, 2010). That is a real, modest finding — but the product contained many nutrients, so it cannot tell us whether B5 contributed anything. A broad review of B vitamins and the brain argues that a whole-group supplement is a reasonable approach when diet is poor (Kennedy, 2016), and a narrative review links each B vitamin, including B5, to fatigue when status is inadequate (Tardy and colleagues, 2020). Neither shows that B5 on its own lifts energy in someone who is already replete.

Bottom line: if you are genuinely short of B5, restoring it matters. If you are not, the evidence that extra B5 raises energy or endurance is weak to negative.

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Is B5 a Fat Burner?

A claim that circulates online is that large doses of B5 let dieters fast "without hunger" and melt body fat. It traces back mainly to one paper: Leung (1995), published in Medical Hypotheses, a journal that exists to publish untested ideas. The author proposed that the ketones produced during dieting reflect a shortage of B5, that B5 supplements would let fat be burned "completely" without ketone formation, and that dieters would therefore feel less hungry and weak. The paper reports, without data, the author's own success treating overweight patients with this approach alongside careful calorie control.

How to weigh it:

• It is a hypothesis paper, not a trial. There was no control group, no blinding and no published dataset that would let anyone check the result. Evidence tier: hypothesis plus uncontrolled clinical impression.
• The premise does not fit modern physiology. As the ketone section above explains, ketone production during a calorie deficit is a normal adaptation that feeds the brain, not wasted energy caused by a vitamin shortage.
• Nobody has confirmed it. In the three decades since, no controlled human trial has shown that pantothenic acid causes fat loss. The 16-week cyclist trial above found no change even in muscle CoA.
• Fat loss follows energy balance. B5 is needed both to burn and to build fat, so adding more of it does not pick a direction for you.

A widely viewed clinician Q&A on B5 puts it fairly: B5 helps the body use fat as fuel, but it is not a weight-loss supplement and will not shift belly fat on its own. That matches the evidence. Where B5 might indirectly matter is in someone truly deficient, whose tiredness makes activity hard — and that person needs a diagnosis, not a fat burner.

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Three Claims, Three Evidence Levels

Most confusion about B5 and energy comes from blending three separate claims into one. They have very different levels of support.

• Corrects a deficiency — strong. The biochemistry is settled, and controlled depletion studies in volunteers produced fatigue when B5 was withheld.
• Boosts energy when you already have enough — weak to negative. Two small cyclist trials found no performance benefit, and the larger-dose one found no rise in muscle CoA. Mixed B-complex trials cannot isolate B5.
• Burns body fat — no evidence. The idea rests on one uncontrolled hypothesis paper.

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Tired All the Time? What to Check First

Fatigue is one of the most common reasons people see a doctor, and isolated B5 deficiency is one of its least likely causes. A systematic review of 26 primary-care studies of patients whose main complaint was tiredness found depression in about 18.5%, anaemia in about 2.8%, serious physical disease in about 4.3% and cancer in about 0.6% (Stadje and colleagues, 2016). Tiredness that is real and persistent deserves a proper look before reaching for any single vitamin.

Common, checkable causes worth ruling out:

• Iron deficiency, with or without anaemia — a blood count and ferritin. See Iron-Deficiency Anemia.
• Underactive thyroid — a TSH test. See Hypothyroidism.
• Vitamin B12 deficiency, especially in older adults, vegans and people on metformin or acid-reducing drugs. See Vitamin B12.
• Sleep — too little of it, or poor-quality sleep from obstructive sleep apnea (loud snoring, waking unrefreshed).
• Low mood or depression, and long-running stress.
• Blood sugar problems, kidney or liver disease, and pregnancy.
• Medicines and alcohol — sedating drugs, some blood-pressure tablets, regular drinking.
• Fatigue lasting six months or more that worsens after exertion may fit chronic fatigue syndrome.

"Adrenal fatigue" is often offered as an explanation for stress-linked tiredness, and B5 is often recommended for it. It is not a recognised medical diagnosis; the reasons are set out on our Adrenal Fatigue page, and what the research does and does not show about B5 and the stress hormones is on Adrenal Support and Stress.

Testing B5 itself

You will sometimes hear that blood and urine tests for B5 are useless. In research, urinary pantothenic acid excretion is in fact the standard marker of B5 status: in the 1976 depletion study it fell clearly as intake dropped, while blood levels moved more slowly (Fry and colleagues, 1976). Commercial "intracellular" or "functional" micronutrient tests, which grow a person's white blood cells with and without added nutrients, are a different method category; their validation for B5 specifically is limited. Our Testing page compares the options.

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B5-Rich Whole Foods for Steady Energy

The name pantothenic comes from the Greek pantothen, "from everywhere", and it fits: almost every whole food contains some. The adult Adequate Intake is 5 mg a day, and a varied whole-food diet usually reaches it without trying. Figures below are from the USDA FoodData Central database (per 100 g as listed there, with a typical serving worked out):

• Beef liver, braised — 7.11 mg per 100 g; about 6.0 mg in a 3-oz (85 g) serving, more than a full day's need.
• Shiitake mushrooms, cooked — 3.59 mg per 100 g; about 2.6 mg in half a cup (73 g).
• Avocado, raw — 1.39 mg per 100 g; about 1.4 mg in half a fruit.
• Eggs, whole — 1.53 mg per 100 g; about 0.77 mg in one large egg (50 g).
• Sweet potato, baked in skin — 0.884 mg per 100 g; about 1.0 mg in a medium potato (114 g).
• Chicken breast, roasted — 0.965 mg per 100 g; about 0.82 mg in 3 oz (85 g).
• Brown rice, cooked — 0.38 mg per 100 g; about 0.74 mg in a cup (195 g). Milling to white rice strips much of the B5 with the bran.
• Lentils, boiled — 0.638 mg per 100 g; about 0.63 mg in half a cup (99 g).
• Sunflower seeds, dried — 1.13 mg per 100 g; about 0.32 mg in a 1-oz (28 g) handful.

An ordinary day — two eggs, a chicken-and-brown-rice lunch, an avocado and a baked sweet potato — adds up to roughly the full 5 mg. B5 is water-soluble and partly lost in processing, freezing and canning, so whole, minimally processed foods carry the most. For "steady energy" in the everyday sense, the bigger levers are regular meals built on protein, whole grains like brown rice, vegetables and healthy fats, plus sleep. See Vitamin B5 Sources for a longer list.

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Safety and Sensible Doses

• Food first. The adult Adequate Intake is 5 mg a day. There is no RDA because there was not enough data to set one, and no Tolerable Upper Intake Level was set by the Institute of Medicine because no clear toxic threshold was identified.
• Large doses are mostly well tolerated, but gram-level doses can cause stomach upset and diarrhoea. The 16-week trial used 6 g a day; that is a research dose, not a target, and it produced no energy benefit.
• The real risk is a missed diagnosis. Treating persistent fatigue with a supplement can delay finding anaemia, thyroid disease, sleep apnea or depression, all of which are treatable.
• Pantethine, a related form studied mainly for cholesterol, is a different question — see Pantethine and Cholesterol.
• For forms, doses and who might reasonably supplement, see Dosing and Supplement Forms and Vitamin B5 Toxicity. People on long-term medicines, heavy drinkers and anyone with malabsorption should read Risk Factors and Depleters.

If you are pregnant, breastfeeding, have kidney disease or take several prescription medicines, discuss any high-dose supplement with your clinician first.

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Key Research Papers

1. Bean WB, Hodges RE, Daum K (1955). Pantothenic acid deficiency induced in human subjects. J Clin Invest. 34(7):1073-84. — PubMed PMID: 14392222
2. Hodges RE, Ohlson MA, Bean WB (1958). Pantothenic acid deficiency in man. J Clin Invest. 37(11):1642-57. — PubMed PMID: 13587673
3. Hodges RE, Bean WB, Ohlson MA, Bleiler R (1959). Human pantothenic acid deficiency produced by omega-methyl pantothenic acid. J Clin Invest. 38:1421-5. — PubMed PMID: 13673099
4. Fry PC, Fox HM, Tao HG (1976). Metabolic response to a pantothenic acid deficient diet in humans. J Nutr Sci Vitaminol (Tokyo). 22(4):339-46. — PubMed PMID: 1011047
5. Webster MJ (1998). Physiological and performance responses to supplementation with thiamin and pantothenic acid derivatives. Eur J Appl Physiol Occup Physiol. 77(6):486-91. — PubMed PMID: 9650731
6. Whitfield J, Harris RC, Broad EM, Patterson AK, Ross MLR, Shaw G, Spriet LL, Burke LM (2021). Chronic pantothenic acid supplementation does not affect muscle coenzyme A content or cycling performance. Appl Physiol Nutr Metab. 46(3):280-283. — PubMed PMID: 33075232
7. Kennedy DO, Veasey R, Watson A, Dodd F, Jones E, Maggini S, Haskell CF (2010). Effects of high-dose B vitamin complex with vitamin C and minerals on subjective mood and performance in healthy males. Psychopharmacology (Berl). 211(1):55-68. — PubMed PMID: 20454891
8. Kennedy DO (2016). B Vitamins and the Brain: Mechanisms, Dose and Efficacy—A Review. Nutrients. 8(2):68. — PubMed PMID: 26828517
9. Tardy AL, Pouteau E, Marquez D, Yilmaz C, Scholey A (2020). Vitamins and Minerals for Energy, Fatigue and Cognition: A Narrative Review of the Biochemical and Clinical Evidence. Nutrients. 12(1):228. — PubMed PMID: 31963141
10. Leung LH (1995). Pantothenic acid as a weight-reducing agent: fasting without hunger, weakness and ketosis. Med Hypotheses. 44(5):403-5. (Hypothesis paper, no controlled data.) — PubMed PMID: 8583972
11. Leonardi R, Zhang YM, Rock CO, Jackowski S (2005). Coenzyme A: back in action. Prog Lipid Res. 44(2-3):125-53. — PubMed PMID: 15893380
12. Czumaj A, Szrok-Jurga S, Hebanowska A, Turyn J, Swierczynski J, Sledzinski T, Stelmanska E (2020). The Pathophysiological Role of CoA. Int J Mol Sci. 21(23):9057. — PubMed PMID: 33260564
13. Stadje R, Dornieden K, Baum E, Becker A, Biroga T, Bösner S, Haasenritter J, Keunecke C, Viniol A, Donner-Banzhoff N (2016). The differential diagnosis of tiredness: a systematic review. BMC Fam Pract. 17(1):147. — PubMed PMID: 27765009

PubMed Topic Searches

1. PubMed: Pantothenic acid and exercise performance
2. PubMed: Human pantothenic acid deficiency
3. PubMed: Coenzyme A and energy metabolism

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Connections

• All Vitamins
• Vitamin B5 (Pantothenic Acid)
• Vitamin B5 Benefits
• Coenzyme A Synthesis
• Adrenal Support and Stress
• Vitamin B5 Deficiency
• Human Deficiency Experiments
• Vitamin B5 Sources
• Dosing and Supplement Forms
• Vitamin B5 Testing
• Vitamin B1 (Thiamine)
• Vitamin B2 (Riboflavin)
• Vitamin B3 (Niacin)
• Carnitine
• Fatigue
• Iron

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