Let’s Talk About the Most Common Nutrient Deficiencies in Runners!
Have you ever left a doctor’s appointment feeling reassured that your lab results were “normal,” only to later realize that, as an athlete, you were actually in sub-optimal ranges? You're not alone! Many runners experience fatigue, sluggish recovery, and underperformance due to overlooked nutrient deficiencies.
The reality? Standard lab reference ranges are based on the general population, not endurance athletes with high training loads, sweat losses, and increased metabolic demands. That’s why it’s essential to understand what “optimal” really looks like for runners. Let’s break down some key nutrients:
Ferritin (Iron Storage Protein)
Why it matters: Ferritin is essential for oxygen transport, endurance, and overall energy production. Runners, especially females, often have lower levels due to foot-strike hemolysis (red blood cell breakdown), sweat losses, and minor GI bleeding from intense training.
Optimal for athletes: 65-150 ng/mL (higher than the general population)
Signs of deficiency: Fatigue, heavy legs, dizziness, shortness of breath, poor recovery.
Vitamin B12
Why it matters: B12 is crucial for red blood cell production, nerve function, and energy metabolism. Endurance athletes may need higher levels than the average person due to increased turnover and muscle repair demands.
Optimal for athletes: Above 500 pg/mL (general range: 200-1100 pg/mL)
Signs of deficiency: Brain fog, tingling in hands/feet, weakness, low endurance.
Vitamin D
Why it matters: This powerhouse vitamin supports bone health, muscle function, immune system strength, and recovery—yet many runners are deficient, especially those training indoors or in colder climates.
Optimal for athletes: 50-100 ng/mL (general range: 30-100 ng/mL)
Signs of deficiency: Frequent injuries, muscle pain, fatigue, low immunity.
Magnesium
Why it matters: Magnesium regulates muscle contraction, relaxation, and energy production. It also plays a key role in recovery and stress management—both of which are crucial for runners.
Optimal for athletes: 0.75-0.95 mmol/L
Signs of deficiency: Muscle cramps, poor sleep, fatigue, irritability, slow recovery.
How to Stay Ahead of Deficiencies
Instead of waiting until fatigue or injury sets in, be proactive! Work with a sports dietitian to assess your nutrient status, optimize your fueling strategy, and ensure you’re getting the right labs done for peak performance.
Get More In-Depth With A Nutrition Consultation
Not sure where to start? Want help navigating lab testing or understanding your results? Book an intro call today and let’s chat about how GracesGrit can support your training!
Grace Thomas, MDN, RDN, LDPerformance Dietitian, Personal Trainer, Speed/Agility CoachGracesGrit Nutrition & Fitness Solutions LLC