Why It Matters
eGFR, or estimated glomerular filtration rate, provides insight into kidney function. Cystatin C corrected eGFR is less affected by muscle mass than other estimation methods, as well as less subject to the influences of age, sex, and race, allowing for a more accurate measurement. (source, source, source)
For athletes and individuals with significant muscle mass, cystatin C-based eGFR resolves a critical limitation of creatinine-based calculations. Because creatinine production scales with muscle mass, standard eGFR can underestimate kidney function in muscular individuals and overestimate it in those with low muscle mass. Cystatin C eGFR eliminates this confounder, providing a cleaner signal of true glomerular filtration, making it the preferred kidney function marker in performance populations where muscle mass and protein intake exceed population norms. (source, source)
Low Cystatin C eGFR: Reduced Kidney Filtration
Low eGFR can be influenced by physiological factors affecting kidney function, as the kidneys play a crucial role in filtering waste products from the blood. From a nutritional standpoint, factors such as excessive intake of sodium along with inadequate hydration can contribute to decreased kidney function and lower eGFR. (source, source, source)
Potential Performance Impact
- Impaired clearance of metabolic waste products, compromising recovery between sessions
- Compromised electrolyte and fluid regulation under training stress
- Accumulation of uremic toxins, impairing cardiovascular and neuromuscular function
- Reduced capacity to handle the metabolic demands of high-intensity training
Optimization
Eat Mediterranean-style meals. Adherence to the Mediterranean diet has been shown to support kidney function by lowering systemic inflammation and cardiometabolic strain. The anti-inflammatory properties of this dietary pattern directly protect glomerular filtration capacity. (source, source)
Protocol: Consume a Mediterranean-style diet rich in fruits, vegetables, whole grains, lean proteins, and healthy fats.
Prioritize proper hydration. Adequate hydration supports renal blood flow and glomerular filtration. Dehydration concentrates waste products and increases kidney workload, contributing to lower eGFR readings. (source, source)
Protocol: Drink at least 0.5 fl oz of water per pound body weight per day.
Avoid smoking. Smoking causes hyperfiltration and oxidative damage to the glomerular endothelium, accelerating kidney function decline. Avoiding smoking protects the filtration membrane and supports sustained eGFR. (source, source)
Protocol: If a smoker, take the steps to quit. If not, avoid areas where secondhand smoke is present.
Supplement with CoQ10. CoQ10 possesses anti-inflammatory and anti-oxidative characteristics that promote kidney and cardiovascular function. By reducing oxidative stress on the glomeruli, CoQ10 supports the filtration capacity measured by cystatin C eGFR. (source, source)
Protocol: Supplement with at least 100 mg of CoQ10.
High Cystatin C eGFR: Favorable Kidney Function
Elevated eGFR can be influenced by physiological factors related to kidney function, as the kidneys play a vital role in filtering waste and excess fluids from the blood. Nutritionally, factors such as adequate hydration and a balanced diet low in sodium can support kidney health and potentially contribute to higher eGFR levels. (source, source)
Generally, high cystatin C eGFR readings are considered to be a sign of good kidney health.
Optimization
High cystatin C eGFR readings usually do not require any specific treatment unless it is associated with a specific illness. There is no suggested nutritional, lifestyle, or supplement-based intervention.
