Riboflavin (vitamin B2)

What Does Riboflavin Do?

Riboflavin, also known as Vitamin B2, is a water-soluble micronutrient that plays a fundamental role in energy metabolism and cellular function. In a pre-workout context, it serves as a critical component of two major coenzymes, FMN and FAD, which are essential for the conversion of carbohydrates, fats, and proteins into usable ATP.

• ATP Production: Riboflavin is a key player in the electron transport chain, the primary pathway your body uses to generate the energy required for muscle contractions.
• Metabolic Efficiency: It helps the body more effectively oxidize macronutrients, ensuring that your pre-workout meal is actually being converted into fuel during your sets.
• Antioxidant Protection: It supports the glutathione redox cycle, helping to neutralize free radicals produced during intense physical exertion and reducing oxidative stress.
• Erythrocyte Support: It aids in the production of red blood cells, which are responsible for carrying oxygen to your working muscles to delay the onset of fatigue.

Clinical vs. Gym Bro Dosing

Key Insight: Riboflavin is water-soluble, meaning your body cannot store it for long periods. A dose of 10mg is more than enough to ensure your metabolic pathways are fully supported for a training session, as any significant excess will simply be filtered out by the kidneys.

Side Effects & Warnings

• Bright Yellow Urine: This is the most famous side effect of Riboflavin. It can turn your urine a neon, fluorescent yellow. This is harmless and simply indicates your body is excreting the excess.
• Increased Urination: Because it is water-soluble, high doses may act as a very mild diuretic in sensitive individuals.
• Digestive Sensitivity: While rare at the 10mg level, massive doses (400mg+) can occasionally cause diarrhea or stomach cramps.

Tip: If you are already taking a high-potency multivitamin or a B-complex, check the labels. You aren't at risk of toxicity, but you might be paying for extra Riboflavin that your body is just going to flush away.