Every time you move, think, or even just breathe, trillions of cells are running the same three-step chemical process to keep you powered. Here's how that process actually works, and which nutrients are doing the behind-the-scenes work.
Written by Vita Globe Editorial Team | Reviewed against peer-reviewed research and NIH guidance
What nutrients does your body actually need to make energy?
Your cells convert food into ATP — the body's energy currency — through cellular respiration in the mitochondria, yielding roughly 32 ATP molecules per glucose molecule when oxygen is available[1]. B-vitamins act as coenzymes at nearly every step of that process[2][4], iron carries the oxygen that makes the efficient version of this process possible[6], and magnesium is required for the energy-production reactions themselves[7].
Caveat: These nutrients matter for energy production when you're actually short on them — fatigue is a documented symptom of B12 deficiency specifically[5] — but because the body stores years' worth of some of them, true deficiency is uncommon and can take a long time to show up. Correcting a real shortfall restores normal function; it isn't a way to get "extra" energy beyond that.
Sources: NIH NIGMS: ATP's Amazing Power · NIH: Iron Fact Sheet · NIH: Magnesium Fact Sheet · Verified 2026-09-06
IN THIS ARTICLE
The ATP Process: Cellular Respiration in Three Stages
Every cell in your body runs on adenosine triphosphate (ATP), which NIH's National Institute of General Medical Sciences describes as "the major source of energy for organisms' biochemical reactions" — essentially the cellular equivalent of electricity powering a device[1]. ATP is produced mainly in the mitochondria, through a process called cellular respiration, which is why mitochondria are often called the "powerhouses" of the cell[1].
The process happens in three connected stages. Glycolysis breaks glucose down into pyruvate in the cell's main body, yielding a small amount of ATP directly. The citric acid cycle (Krebs cycle) then processes those breakdown products further, generating electron carriers. Finally, the electron transport chain uses those carriers, along with oxygen, to generate the majority of your ATP — when oxygen is available, this full pathway yields roughly 32 ATP molecules per glucose molecule, versus just 2 from fermentation without oxygen[1].
B-Vitamins: The Coenzyme Team
B-vitamins don't provide energy themselves — they act as coenzymes, the helper molecules that let the enzymes running cellular respiration actually function. Thiamine (B1) is a good example: NIH's fact sheet notes it "plays a critical role in energy metabolism," with its active form serving as "an essential cofactor for five enzymes involved in glucose, amino acid, and lipid metabolism"[2].
Riboflavin (B2) forms the coenzyme FAD, which NIH describes as playing "major roles in energy production" and metabolism more broadly[3]. Niacin (B3) forms NAD, which is "primarily involved in catabolic reactions that transfer the potential energy in carbohydrates, fats, and proteins to ATP" — with more than 400 enzymes in the body depending on it[4]. And B12 supports healthy red blood cell formation[5] — relevant to energy indirectly, since those cells are what deliver the oxygen the electron transport chain needs.
B-vitamins are found in leafy greens, whole grains, eggs, and fortified cereals; B12 specifically comes only from animal products or fortified foods, which is why vegans and vegetarians are more commonly advised to supplement it. Fatigue is a listed symptom of B12 deficiency specifically[5], though because the body stores several years' worth of B12, deficiency symptoms can take a long time to appear.
If all this coenzyme detail has you wondering whether a multivitamin is worth taking in the first place, that's a fair question — we broke down what the research actually supports.
Iron: Getting Oxygen to the Party
Remember that the oxygen-using version of cellular respiration produces roughly 16 times more ATP than the version without oxygen. Iron is what makes that efficient version possible: it's "an essential component of hemoglobin," the red blood cell protein that "transfers oxygen from the lungs to the tissues," according to NIH's fact sheet[6]. Without enough iron, your tissues — including your muscles and brain — get less of the oxygen that makes efficient ATP production possible.
That's why iron deficiency anemia's hallmark symptoms are "weakness, fatigue, and difficulty concentrating"[6] — it's a direct, mechanistic consequence of cells not getting enough oxygen to run efficient respiration. Iron-rich foods include lean meats, spinach, and legumes. One practical detail: vitamin C "enhances the bioavailability of nonheme iron" (the type found in plant foods), while compounds in tea and coffee can reduce absorption — so pairing a plant-based iron source with a vitamin C source, and spacing iron-rich meals away from tea or coffee, can meaningfully improve how much you actually absorb[6].
Magnesium: Stabilizing the Energy Currency
Magnesium's role is less well-known but just as fundamental: NIH's fact sheet states magnesium "is required for energy production, oxidative phosphorylation, and glycolysis"[7] — in other words, it's directly involved in more than one stage of the cellular respiration process described above. ATP itself is typically bound to a magnesium ion in the cell (as Mg-ATP) for stability, which is part of why adequate magnesium status matters for how efficiently your cells can actually use the ATP they produce.
Nuts, seeds, whole grains, and dark leafy greens are good dietary sources. Because magnesium is involved in hundreds of enzymatic reactions throughout the body, it's one of the more broadly relevant nutrients on this list, even though it rarely gets top billing next to B-vitamins and iron.
The honest summary
- ATP, made in your mitochondria, is the actual "energy" your cells run on — and with oxygen, that process is about 16 times more efficient than without it[1].
- B-vitamins, iron, and magnesium each play a specific, well-documented role in that process — they're not interchangeable "energy" nutrients, each does a different job[2][6][7].
- Fatigue is a real, documented symptom of both iron and B12 deficiency specifically — if low energy is persistent, it's worth checking with a doctor rather than assuming a supplement will fix it[5][6].
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Frequently Asked Questions
Will taking B-vitamins give me more energy if I'm not deficient?
Not necessarily. B-vitamins act as coenzymes in energy metabolism, but they don't add extra fuel the way food does — they help enzymes do their job. If you're already getting enough from your diet, more won't speed up ATP production. Where supplementation tends to help is when intake is genuinely low, absorption is impaired (common with age or certain medications), or you follow a diet — like vegan or vegetarian — that makes B12 harder to get from food alone.
Why does low iron specifically cause fatigue?
Iron is a core component of hemoglobin, the protein that carries oxygen from your lungs to every cell in your body. Without enough oxygen reaching your mitochondria, cells can't run the oxygen-dependent stage of energy production efficiently and fall back on far less efficient pathways. The result is the classic iron-deficiency symptom set: persistent tiredness, weakness, and difficulty concentrating.
What does coenzyme actually mean?
A coenzyme is a small molecule an enzyme needs alongside its main substrate to catalyze a reaction — a required helper rather than the star of the show. Several B-vitamins are converted into coenzymes (like FAD from riboflavin or NAD from niacin) that shuttle electrons during cellular respiration. Without them, the enzymes involved in the Krebs cycle and electron transport chain can't function.
What's the difference between B12 and B Complex gummies?
B12 gummies provide just vitamin B12, most relevant if you're on a plant-based diet or have a diagnosed B12 gap. B Complex gummies provide a fuller set of B vitamins (B1, B2, B3, B6, B12, and others), each acting as a coenzyme at a different step of energy metabolism. Neither "does more" than the other — they cover different parts of the same process.
Sources
- National Institute of General Medical Sciences. Science Snippet: ATP's Amazing Power.
- National Institutes of Health, Office of Dietary Supplements. Thiamin - Fact Sheet for Health Professionals.
- National Institutes of Health, Office of Dietary Supplements. Riboflavin - Fact Sheet for Health Professionals.
- National Institutes of Health, Office of Dietary Supplements. Niacin - Fact Sheet for Health Professionals.
- National Institutes of Health, Office of Dietary Supplements. Vitamin B12 - Fact Sheet for Health Professionals.
- National Institutes of Health, Office of Dietary Supplements. Iron - Fact Sheet for Health Professionals.
- National Institutes of Health, Office of Dietary Supplements. Magnesium - Fact Sheet for Health Professionals.
About the Vita Globe Editorial Team
The Vita Globe Editorial Team researches and writes our wellness content, working from peer-reviewed research, systematic reviews and guidance from bodies such as the NIH. We cite our sources inline and update articles when the evidence changes.
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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. The content in this article is for informational purposes only and is not a substitute for professional medical advice.
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