Does Fish Oil Raise Creatinine? Understanding the Connection

November 21, 2025 •

3 min read

According to extensive studies, fish oil and omega-3 fatty acids are generally shown to improve or protect kidney function, not harm it. This counters the common misconception that fish oil raises creatinine levels, which is a key indicator of kidney health.

Quick Summary

This article explores the relationship between fish oil supplementation and creatinine levels. It examines the latest research findings, explaining how omega-3 fatty acids primarily benefit kidney function by reducing inflammation and improving health markers. We discuss the nuanced factors that influence creatinine and emphasize the overall protective role of fish oil for renal health.

Key Points

Fish oil does not raise creatinine: Scientific studies show that fish oil supplementation does not increase creatinine levels and may even help improve kidney function, particularly in those with chronic kidney disease (CKD).
Omega-3s have anti-inflammatory benefits: The omega-3 fatty acids in fish oil reduce inflammation and oxidative stress, which are major factors in the progression of kidney disease.
Creatine vs. creatinine confusion: The misconception that fish oil raises creatinine likely stems from confusion with creatine supplements, which are known to increase creatinine levels.
Dietary protein affects creatinine: Consuming large amounts of cooked meat or fish can cause a temporary, non-harmful elevation in creatinine levels, which is a distinct effect from fish oil supplementation.
Fish oil benefits for renal health: Research indicates fish oil can slow the rate of kidney function loss in specific conditions like IgA nephropathy and lower blood pressure, which reduces kidney strain.
Consult a healthcare provider: If you have concerns about kidney health or are taking medications, it is essential to speak with a doctor before starting any new supplement.

The Truth About Fish Oil and Kidney Function

Creatinine is a waste product from muscle metabolism that is filtered out of the blood by the kidneys. Its levels serve as a critical marker for assessing kidney health. The question of whether fish oil raises creatinine is therefore a significant concern for many health-conscious individuals. However, the available scientific evidence overwhelmingly suggests that for most people, fish oil and its omega-3 fatty acids (EPA and DHA) are beneficial for renal health rather than detrimental.

Research indicates that fish oil can play a protective role in kidney function, especially in individuals with pre-existing conditions like chronic kidney disease (CKD) or diabetes. For instance, a 2025 study found that omega-3 supplementation significantly improved both blood urea nitrogen (BUN) and creatinine levels in CKD patients on hemodialysis. This protective effect is largely attributed to the anti-inflammatory properties of omega-3s, which help reduce renal inflammation and oxidative stress.

How Omega-3 Fatty Acids Support Kidney Health

Reduced Inflammation: Omega-3s possess potent anti-inflammatory effects that can mitigate the damage caused by inflammation in the kidneys. This is particularly relevant for conditions like IgA nephropathy, where studies have shown fish oil can slow the loss of renal function.
Improved Hemodynamics: By influencing the production of eicosanoids and cytokines, fish oil can alter renal blood flow. This improved blood flow helps maintain the kidneys' filtering capacity.
Lowered Blood Pressure: High blood pressure is a major risk factor for kidney disease. Fish oil has been shown to slightly lower blood pressure, which in turn reduces the strain on the kidneys.
Positive Lipid Profile Effects: Omega-3 supplementation can improve lipid profiles, including reducing triglycerides, which can be beneficial for overall cardiovascular and renal health.

Factors That Can Affect Creatinine Levels

While fish oil itself does not typically raise creatinine, it's important to recognize that many other factors can influence these levels. These can range from dietary habits to underlying health conditions.

Dietary Protein Intake: Consuming large amounts of cooked meat, including fish, can cause a temporary increase in creatinine levels due to the conversion of creatine during cooking. This is not an effect of fish oil but rather the protein content of the meat.
Muscle Mass: Individuals with higher muscle mass naturally have higher creatinine levels. This is why creatinine levels are often interpreted relative to a person's age, gender, and body size.
Hydration Status: Dehydration can lead to a higher concentration of creatinine in the blood, creating a temporarily elevated reading.
Medications: Certain drugs, like some antibiotics and nonsteroidal anti-inflammatory drugs (NSAIDs), can affect kidney function and, as a result, impact creatinine levels.

Fish Oil vs. Creatine Supplementation: Clarifying the Confusion

A common point of confusion stems from the similarity of the names "fish oil" and "creatine." They are entirely different substances. Creatine, a popular supplement for athletes, is known to raise creatinine levels because it's the muscle waste product being measured. Fish oil, on the other hand, contains omega-3 fatty acids (EPA and DHA), and has no connection to the creatine-creatinine pathway. It is crucial not to confuse the two supplements when assessing their effects on kidney health.

Comparison of Fish Oil Benefits and Dietary Factors on Kidney Health


Feature	Fish Oil (Omega-3s)	Dietary Factors (High Protein)
Effect on Kidneys	Generally protective; reduces inflammation	Can cause temporary increase in creatinine
Mechanism	Anti-inflammatory action; improved hemodynamics	Normal metabolic breakdown of creatine in muscle
Creatinine Impact	Studies show potential to lower creatinine	Can lead to a transient, non-harmful rise in creatinine
Long-Term Renal Health	Associated with delayed progression of CKD	No long-term negative impact on healthy kidneys, but can influence test results

Conclusion

For most people, the notion that fish oil raises creatinine is a misconception. In fact, robust scientific research indicates that the anti-inflammatory and protective effects of omega-3 fatty acids can be beneficial for kidney function, especially in individuals with existing kidney issues like CKD. While other factors, such as high protein meals or dehydration, can temporarily influence creatinine levels, they should not be confused with the effects of fish oil supplementation. If you have concerns about your kidney health or creatinine levels, it is always best to consult with a healthcare provider for personalized advice.

This authoritative medical resource provides further reading on the effects of omega-3 supplementation in patients with chronic kidney disease: PubMed Central.

Frequently Asked Questions

While fish oil itself is not known to negatively affect kidney function or cause a false positive result, other dietary factors, such as eating a large amount of cooked fish or meat, can temporarily raise creatinine levels and impact test results. It is best to inform your doctor of all supplements you take.

Yes, several studies indicate that fish oil is not only safe for individuals with CKD but may also offer therapeutic benefits. It has been shown to reduce inflammation and potentially improve kidney function markers in some patients.

Creatine is a substance primarily found in muscle tissue and taken by athletes as a supplement. Creatinine is a waste product that the kidneys filter from the blood. Creatine supplementation can lead to higher creatinine levels, but fish oil has no connection to this metabolic pathway.

Eating fatty fish, like any other cooked meat, can temporarily cause a slight increase in blood creatinine levels. This is due to the natural creatine content in muscle protein, and the effect is transient.

In some specific medical contexts, particularly involving kidney inflammation, studies have shown that fish oil supplementation was associated with lower or improved creatinine levels compared to placebo groups. However, this is not a universal effect and depends on the underlying health condition.

Standard doses of fish oil are generally well-tolerated. The most common side effects are gastrointestinal upset and a fishy aftertaste, not adverse effects on kidney function. The risk of bleeding might theoretically increase with very high doses, but this is a separate consideration.