Nasal SprayFrom $166/mo
InjectionFrom $166/mo
Medically reviewed by Vanessa Niles, R.N., M.D., F.A.C.O.G. —
Definition
Krebs cycle, in plain English
Fuel from carbohydrates, fats and proteins enters the cycle as acetyl-CoA. Each turn releases carbon dioxide and captures energy in carrier molecules.
Each turn makes 3 NADH, 1 FADH₂ and 1 GTP (or ATP). StatPearls describes steps such as the alpha-ketoglutarate dehydrogenase reaction producing NADH, carbon dioxide and a hydrogen ion.
- Also called
- Citric acid cycle, TCA cycle
- Location
- Mitochondria
- Per turn
- 3 NADH, 1 FADH₂, 1 GTP
How it connects
How Krebs cycle relates to NAD+
The Krebs cycle needs a steady supply of NAD+ to keep turning. If NADH can't hand off its electrons, NAD+ runs short and the cycle slows.
For your treatment
What Krebs cycle means for NAD+ therapy
That's one reason NAD+ is called essential for energy metabolism. Essential doesn't mean that taking more improves energy in healthy people, though.
- Free online consultation with a licensed U.S. provider
- NAD+ nasal spray or injection, plans from $166 a month if prescribed
- NAD+ has no FDA-approved use; compounded NAD+ isn’t FDA-approved
Questions
Krebs cycle: common questions
What is the Krebs cycle?
The Krebs cycle, or citric acid cycle, is a loop of reactions in mitochondria that breaks down fuel from food and loads electrons onto NAD+ to make NADH for energy.
Why is it called a cycle?
Its last step regenerates oxaloacetate, the molecule the first step uses, so it runs in a loop.
Who was Krebs?
Sir Hans Krebs described the cycle in 1937 and shared the 1953 Nobel Prize in Physiology or Medicine for the discovery.
Will NAD+ therapy give me more energy?
That hasn't been shown in healthy people. NAD+ is essential for making ATP, but taking more hasn't been proven to raise energy.
Does exercise affect NAD+?
Exercise has been linked to higher NAMPT, the NAD+ recycling enzyme, in muscle in research studies, and regular activity supports healthy aging.
Should I see a doctor about tiredness first?
Yes, if it's new or lasting. MedlinePlus lists many causes of fatigue, including anemia, depression, medicines and sleep disorders.
Keep learning
Related NAD+ terms
Terms that connect to Krebs cycle, each explained on its own page.
- Cell energyMitochondriaMitochondria are structures inside cells that turn energy from food into ATP, the cell's main energy currency. NAD+ and NADH are central to how they do it.
- MoleculesNADHNADH is the reduced form of NAD+. It carries high-energy electrons from the breakdown of food to the electron transport chain in mitochondria, where they help make ATP.
- Cell energyElectron transport chainThe electron transport chain is a series of four protein complexes in the inner membrane of mitochondria. It takes electrons from NADH, passes them to oxygen and uses the energy to make ATP.
- Cell energyATPATP (adenosine triphosphate) is the main energy currency of cells. Most of it is made in mitochondria using electrons carried by NADH, which is why NAD+ is tied to energy.
Official sources
Krebs cycle: sources and official resources
Official government and research sources behind this page, so you can check the facts yourself.
- NIH National Library of Medicine (StatPearls)Physiology, Krebs Cycle
The citric acid cycle step by step, including the steps that make NADH.
- NIH National Library of Medicine (StatPearls)Biochemistry, Electron Transport Chain
How four protein complexes use electrons from NADH to drive ATP production.
- NIH Office of Dietary SupplementsNiacin: Health Professional Fact Sheet
Explains how the body turns niacin (vitamin B3) into NAD, a coenzyme used by more than 400 enzymes.
- MedlinePlus Genetics (National Library of Medicine)Mitochondrial DNA
What mitochondria do, including making ATP, the cell's main energy source.
Medically reviewed by Dr. Vanessa Niles, R.N., M.D., F.A.C.O.G., on October 12, 2026. This glossary is general education, not medical advice. NAD+ has no FDA-approved use, and compounded NAD+ is not FDA-approved or evaluated by the FDA for safety or effectiveness. Talk with a licensed provider before starting any supplement or treatment.
Questions about NAD+? Ask a provider
Book a free online consultation. A licensed U.S. provider reviews your health and, if NAD+ fits, prescribes the nasal spray or injection, with plans from $166 a month.
Book a free consultation