09/18/2025
As an endurance athlete and as a dietitian who works with athletes, I’m always looking for ways to optimize performance and overall health. That’s why I run specific functional labs, like ferritin and vitamin D, to gain deeper insights beyond standard blood tests.
1. Ferritin is a crucial marker of iron storage in the body. Iron is essential for oxygen transport and energy production, especially during endurance activities. Low ferritin levels can lead to fatigue, decreased stamina, and even injury risk, so monitoring it helps ensure your body has what it needs to perform at its best.
2. Vitamin D plays a vital role in bone health, immune function, and mood regulation. For endurance athletes, maintaining sufficient vitamin D levels can improve recovery, reduce injury risk, and support mental resilience during training and competitions. Supplementation is necessary in the winter months in Wisconsin. Even with direct sunlight, the sun’s rays are not strong enough to synthesize vitamin D in the skin.
By checking these levels regularly, I can tailor your nutrition and supplementation strategy, whether that’s adjusting iron-rich foods, optimizing sun exposure, or supplementing when necessary to keep your body functioning optimally. This proactive approach isn’t just for athletes; it’s a valuable tool for anyone looking to support their health and performance from the inside out.
If you’re an endurance athlete or someone working toward your health goals, consider advocating for these functional labs. They can reveal underlying deficiencies or imbalances that might be holding you back and sometimes even before symptoms appear.
