Pre-Workout Supplements May Elevate Your Liver Enzymes

Jad Ismail
2 min readApr 22


I love caffeine, and more importantly, pre-workout supplements. They give me a good boost for my workouts, no matter when I take them. However, from my experience and research, I discovered that there is a gap between nutrition science and healthcare. Pre-workout supplements can increase liver enzyme levels, which can cause confusion between you and your doctor. Healthcare providers may not always have sufficient nutritional information, especially since nutrition is still an evolving science in its infancy.

Picture by Anthony

Niacin: The Key Ingredient in Pre-Workout Supplements

One common ingredient found in pre-workout supplements is Niacin, also known as vitamin B3; It’s a water-soluble vitamin that plays an important role in various bodily functions, including energy production, DNA repair, and cell signaling. It is found in many foods, including meat, fish, and poultry, as well as in supplements. But it can also be synthesized in the body from the amino acid tryptophan. The average person consumes around 20 mg of niacin daily from food sources.

In pre-workouts, Niacin is used for its potential in energy production, improving blood flow, and reducing fatigue. The recommended daily intake of niacin is 16 milligrams for men and 14 milligrams for women.

Some pre-workout supplements may contain as much as 500 milligrams or more of niacin per serving, far exceeding the recommended daily intake.

Niacin and Liver Enzymes: Evidence from Studies

One study published in the American Journal of Cardiology found that niacin therapy at a dose of 500mg caused an increase in liver enzyme levels in some patients with high cholesterol levels.

The increase in liver enzymes is typically mild and reversible once the niacin therapy is discontinued. Therefore, it is important to disclose any supplements you are taking to your healthcare provider before undergoing blood work, and it is better to take a break for a few days prior to the test to ensure accurate results and avoid any unnecessary confusion. It is also worth mentioning that not all individuals may experience an increase in liver enzymes with niacin supplementation, as individual responses may vary.

Take off:

Overall, it is important to be mindful of the vitamins we take in supplements and to stick to the recommended daily intake to avoid any potential negative effects on liver health.



Jad Ismail

Hello, I'm Jad Ismail, a scientist, engineer, and blogger with a background in fitness, nutrition, and technology.