Explanation
The BUN-to-creatinine ratio is an indicator of kidney health and hydration. (source, source)
Low
A low BUN/creatinine ratio may be influenced by physiological factors involving kidney function and hydration status, as both blood urea nitrogen (BUN) and creatinine are markers of kidney health. From a nutritional perspective, factors such as low protein intake or hydration status can contribute to a lower ratio. (source, source, source, source)
Optimization
Prioritize high-quality protein: Low protein intake has been shown to negatively affect serum BUN levels. (source) Urea is the primary metabolite derived from dietary protein intake and tissue protein turnover, thus low BUN levels would be a result of low protein intake. (source) Recommendation: Eat 0.8 to 1.0 g of protein per pound of body weight per day.
One serving examples: Eggs (3 large eggs), Chicken Breast (3.5 oz), Beef (lean cuts) (3.5 oz), Salmon (3 oz), Pork (lean cuts) (3.5 oz), Tofu (3.5 oz)
Avoid alcohol: Alcohol consumption has been associated with low BUN levels. (source) Alcohol consumption contributes to a reduction in the body’s ability to convert amino nitrogen into urea. (source) Recommendation: Monitor alcohol intake. Try to limit consumption to one or two drinks daily, with the goal of less than three per week.
Supplement with a quality protein source: Low protein intake has been shown to negatively affect serum BUN levels. (source) Urea is the primary metabolite derived from dietary protein intake and tissue protein turnover, thus low BUN levels would be a result of low protein intake. (source) Recommendation: Supplement with 20 to 40 g of quality protein with a goal of consuming 0.8 to 1.2 g of protein per pound of body weight per day.
Prioritize fiber-rich foods: Daily fiber intake has been shown to reduce creatinine levels. (source) Fiber increases the stool bulk and provides a fecal route of excretion for nitrogenous waste, including creatinine, resulting in decreased levels of creatinine in the body. (source, source) Further, fiber aids in supporting bacterial creatinase, which breaks down creatinine, in the intestine. (source) Recommendation: Incorporate fiber-rich foods with the target of at least 30 g of fiber per day.
One serving examples: Chia Seeds (2 tbs), Flaxseeds (2 tbs), Lentils (1 cup), Steel Cut Oats (1 cup), Avocado (1 medium Avocado)
Supplement with vitamin C: Low vitamin C is associated with high creatinine concentrations. (source) Vitamin C supplementation improves endothelial function of the kidneys, resulting in enhanced kidney function, including the ability to metabolize and clear waste, like creatinine, from the blood. (source) Recommendation: Supplement with at least 100 mg of vitamin C daily.
High
A high BUN/creatinine ratio can stem from physiological factors relating to the kidneys, as these organs filter waste products from the blood. Nutritionally, factors like dehydration or excessive protein intake can influence this ratio. (source, source, source)
Optimization
Avoid smoking: Smokers have been shown to have higher BUN concentrations than nonsmokers. (source) Smoking is associated with renal function deterioration mediated by elevated homocysteine levels. (source) As kidney function diminishes, BUN concentrations rise. Recommendation: If a smoker, take the steps to quit. If not, avoid areas where secondhand smoke is present.
Supplement with a vitamin B complex: Low levels of vitamins B1 and B2 have been associated with high BUN concentrations. (source) Supplementation with vitamin B complex helps suppress oxidative pathways that hinder kidney health and function. (source) Supporting kidney health helps to lower BUN concentrations. Recommendation: Supplement with a vitamin B complex that has at least 50% of daily recommendations for each B vitamin.
Limit foods high in fiber: Daily fiber intake has been shown to reduce creatinine levels. (source) Fiber increases the bulk of the stool and provides a fecal route of excretion for nitrogenous waste, including creatinine. (source, source) Further, fiber aids in supporting bacterial creatinase, which breaks down creatinine, in the intestine. (source) Limiting fiber intake regulates creatinine levels in the body. Recommendation: Monitor and limit excess intake of fiber-rich foods, like oats, beans, and whole grains.
Exercise at a high intensity: High-intensity resistance training increases creatinine levels. (source) Exercise induces muscle damage that results in elevated creatinine levels. (source) Recommendation: Recommendation: Follow a structured program ensuring at least 75 minutes of 75% Max Heart Rate or greater weekly.
