What Vitamins Are Found in NADH and FADH2?

January 13, 2026 •

2 min read

Over 400 enzymes in the human body require the coenzyme NAD (the oxidized form of NADH) to function, making its precursor, vitamin B3 (niacin), absolutely essential. This highlights the critical connection between dietary intake and fundamental biological processes like energy production, where key electron carriers containing vitamins are found in NADH and FADH2.

Quick Summary

The coenzymes NADH and FADH2, crucial for cellular energy production, are synthesized from the B vitamins niacin (B3) and riboflavin (B2), respectively. These vitamin derivatives function as electron carriers in cellular respiration's energy transfer steps.

Key Points

NADH Origin: NADH is derived from niacin (vitamin B3).
FADH2 Origin: FADH2 is derived from riboflavin (vitamin B2).
Electron Carriers: Both transport electrons in cellular respiration.
Energy Yield Difference: NADH yields more ATP than FADH2 due to its entry point in the ETC.
Dietary Necessity: B vitamins must be obtained from the diet for energy metabolism.
Metabolic Pathways: Essential for glycolysis and the citric acid cycle.

The Foundation of Cellular Energy

At the heart of cellular energy production lie two vital coenzymes, NADH and FADH2. They act as electron carriers during cellular respiration, a process that converts food into usable energy in the form of ATP (adenosine triphosphate). Their function is to transport high-energy electrons to the electron transport chain, where the majority of ATP is produced. These complex molecules are derived from essential B vitamins.

Vitamin B3: The Core of NADH

NADH, or nicotinamide adenine dinucleotide, is the reduced form of NAD+. It is derived from vitamin B3, also known as niacin. The nicotinamide component of the vitamin is integrated into the NAD+ structure. NADH plays a crucial role in glycolysis and the citric acid cycle by accepting electrons. Niacin is found in meat, fish, eggs, milk, and fortified cereals.

Vitamin B2: The Backbone of FADH2

FADH2, or flavin adenine dinucleotide, is formed from the reduced coenzyme FAD. Its precursor is vitamin B2, known as riboflavin. The flavin portion of FAD is synthesized directly from riboflavin. FADH2 is produced during the citric acid cycle and transports electrons to the electron transport chain. Riboflavin is abundant in dairy products, eggs, meat, and fortified grains.

The Importance of a Balanced Diet

Obtaining necessary B vitamins through diet is essential as the body cannot synthesize them. Deficiencies in niacin or riboflavin impair NADH and FADH2 production, leading to metabolic issues like fatigue.

Comparison: NADH vs. FADH2

Here is a comparison of their key properties and functions in cellular energy production.


Feature	NADH (Derived from Niacin - B3)	FADH2 (Derived from Riboflavin - B2)
Precursor Vitamin	Vitamin B3 (Niacin)	Vitamin B2 (Riboflavin)
Energy Yield	~2.5-3 ATP	~1.5-2 ATP
Entry Point into ETC	Complex I	Complex II
Energy Level	Higher energy boost	Lower energy boost
Metabolic Stage	Glycolysis and Citric Acid Cycle	Citric Acid Cycle

What Happens During Cellular Respiration?

Cellular respiration involves breaking down glucose for energy.

Glycolysis: Initial glucose breakdown producing ATP and NADH.
Pyruvate Oxidation: Produces additional NADH.
Citric Acid Cycle: Generates NADH, FADH2, and some ATP. FADH2 is formed during succinate oxidation.
Electron Transport Chain: NADH and FADH2 donate electrons, driving ATP synthesis.

Conclusion

NADH and FADH2 are derived from niacin (B3) and riboflavin (B2) and are crucial electron carriers in cellular respiration. A balanced diet with sufficient B vitamins is essential for healthy metabolism and energy production.

The Link Between B Vitamins and Cellular Energy

For a deeper look into the broader roles of the B vitamin complex, you can refer to authoritative sources such as the National Institutes of Health.

List of Foods Rich in Relevant B Vitamins

Ensuring adequate intake supports NADH and FADH2 production:

Rich in Niacin (B3): Poultry, beef, salmon, fortified cereals, legumes.
Rich in Riboflavin (B2): Dairy products, eggs, organ meats, mushrooms, leafy greens.

This connection highlights the impact of micronutrients on cellular energy and efficiency.

Frequently Asked Questions

They carry high-energy electrons to the electron transport chain for ATP production.

From the diet: niacin (B3) for NADH and riboflavin (B2) for FADH2.

Niacin is vitamin B3. The body converts it to NAD+, which is reduced to NADH for electron transport.

Riboflavin is vitamin B2. It's a precursor to FAD, which is reduced to FADH2 during the citric acid cycle for the ETC.

Deficiency can impair NADH and FADH2 production, reducing energy and causing fatigue and metabolic issues.

NADH enters the ETC at an earlier, higher energy point (Complex I), while FADH2 enters later (Complex II), resulting in less ATP.

The body efficiently recycles these coenzymes. A balanced diet with B3 and B2 is usually sufficient. Consult a healthcare professional about supplements.