Galectin-3
Also known as: Gal-3
What Does Galectin-3 Measure?
Galectin-3 (Gal-3) is a protein belonging to the galectin family of carbohydrate-binding proteins. A blood test measuring Galectin-3 quantifies the circulating levels of this protein in the bloodstream, typically expressed in nanograms per milliliter (ng/mL). Galectin-3 is primarily secreted by activated macrophages and other immune cells and plays a central role in mediating inflammation, cell adhesion, cell proliferation, and fibrosis (scarring) in tissues throughout the body.
Why Does Galectin-3 Matter?
Galectin-3 has emerged as a clinically significant biomarker primarily in the context of heart failure, where elevated levels are strongly associated with cardiac fibrosis and adverse outcomes. It serves as a prognostic tool approved by the FDA to assess the risk of hospitalization and mortality in patients with chronic heart failure. Beyond cardiology, elevated Galectin-3 is linked to fibrotic diseases of the liver, kidneys, and lungs, as well as certain cancers, making it a broad indicator of chronic inflammation and tissue remodeling. Monitoring Galectin-3 can help clinicians guide treatment decisions, assess disease progression, and evaluate therapeutic responses.
Normal Ranges
Males
Less than 17.8 ng/mL (adult males; values above 25.9 ng/mL are considered high risk in heart failure)
Females
Less than 17.8 ng/mL (adult females; values above 25.9 ng/mL are considered high risk in heart failure)
Children
Not well established in pediatric populations; consult age-specific reference ranges
Causes of High Levels
- Chronic heart failure and cardiac fibrosis — elevated Galectin-3 reflects ongoing scarring of heart tissue
- Chronic kidney disease — impaired kidney clearance and renal fibrosis drive higher levels
- Liver fibrosis and cirrhosis — activation of hepatic stellate cells increases Galectin-3 secretion
- Pulmonary fibrosis — macrophage-driven fibrosis in the lungs elevates circulating levels
- Cancer — various malignancies including colorectal, prostate, breast, and thyroid cancer are associated with increased Galectin-3 expression
- Chronic systemic inflammation — conditions such as rheumatoid arthritis, inflammatory bowel disease, and metabolic syndrome can raise Galectin-3 levels
Causes of Low Levels
- Absence of significant fibrotic or inflammatory disease — healthy individuals with no underlying organ fibrosis tend to have low baseline levels
- Effective treatment of heart failure — successful management with medications can reduce Galectin-3 over time
How to Improve Your Galectin-3
Diet
- Increase dietary fiber intake (fruits, vegetables, legumes, whole grains) — soluble fiber, particularly pectin found in apples and citrus, has been shown to inhibit Galectin-3 activity
- Consume anti-inflammatory foods such as fatty fish (salmon, mackerel), olive oil, walnuts, and leafy greens to reduce the chronic inflammation that drives Galectin-3 elevation
- Reduce ultra-processed foods, refined sugars, and trans fats which promote systemic inflammation and metabolic dysfunction
- Follow a Mediterranean-style diet rich in polyphenols, which has been associated with reduced cardiac and hepatic fibrosis markers
- Limit excessive alcohol consumption to reduce liver fibrosis progression and associated Galectin-3 elevation
Supplements
- Modified Citrus Pectin (MCP) at 5–15 grams per day — the most evidence-backed Galectin-3 inhibitor; research shows it can measurably reduce circulating levels and block Galectin-3's pro-fibrotic activity
- Omega-3 fatty acids (EPA + DHA) at 2–4 grams per day — reduce systemic inflammation and may attenuate fibrotic signaling pathways
- Curcumin (turmeric extract) at 500–1,000 mg per day with piperine for absorption — demonstrates anti-inflammatory and anti-fibrotic properties in preclinical and early clinical studies
Related Biomarkers
Frequently Asked Questions
What is Galectin-3 and why would my doctor order this test?
Galectin-3 is a protein involved in inflammation and tissue scarring (fibrosis). Your doctor is most likely to order this test if you have heart failure, to assess your risk of hospitalization or worsening of the condition. It may also be used if there are concerns about fibrosis in other organs such as the liver or kidneys, or to monitor certain inflammatory or malignant conditions. It is a prognostic marker, meaning it helps predict the course of disease rather than diagnose a specific condition.
What does a high Galectin-3 level mean?
A high Galectin-3 level generally indicates increased fibrotic activity and inflammation in the body. In the context of heart failure, levels above 25.9 ng/mL are considered high risk and are associated with greater likelihood of hospital readmission or death. Elevated levels can also reflect fibrosis in the liver, lungs, or kidneys, chronic inflammatory disease, or certain cancers. A high result should always be interpreted by your doctor in the context of your symptoms, medical history, and other test results.
Can Galectin-3 levels be lowered naturally?
There is growing evidence that certain lifestyle and dietary changes can help reduce Galectin-3 levels. The most studied natural intervention is Modified Citrus Pectin (MCP), a dietary fiber supplement derived from citrus peel that directly inhibits Galectin-3 activity. An anti-inflammatory diet rich in fiber, omega-3 fatty acids, and polyphenols, combined with regular exercise and weight management, can reduce the underlying inflammation and fibrosis that drive elevated Galectin-3. However, any approach to lowering Galectin-3 should be discussed with and supervised by your healthcare provider.