The liver, a vital organ responsible for detoxification, metabolism, and hormone regulation, plays a crucial role in maintaining overall bodily homeostasis. While the liver is primarily known for its functions in digestion and detoxification, its influence extends to the cardiovascular system, particularly in regulating blood pressure and fluid retention. Understanding the liver’s role in these processes sheds light on how liver health can significantly impact conditions such as hypertension and edema (fluid retention), particularly in people with impaired liver function.
The Liver’s Role in Blood Pressure Regulation
Blood pressure is primarily regulated by the autonomic nervous system, the kidneys, and hormonal systems like the renin-angiotensin-aldosterone system (RAAS). However, the liver also plays a substantial, though often underappreciated, role in this regulation. The liver produces angiotensinogen, a precursor to angiotensin II, a powerful vasoconstrictor that increases blood pressure. Dysfunction in the liver can lead to an imbalance in angiotensinogen production, potentially leading to abnormalities in blood pressure regulation.
Moreover, the liver detoxifies and breaks down various hormones, including aldosterone, a hormone that increases sodium and water retention, thereby raising blood pressure. In advanced liver disease (cirrhosis), aldosterone levels do rise, mainly because the kidneys switch on the RAAS in response to a low effective blood volume, with slower breakdown in the liver adding to it. This drives sodium and water retention, but blood pressure in cirrhosis tends to fall rather than rise: arteries in the gut widen, and the extra sympathetic nervous system activity is the body’s attempt to hold pressure up.
The better-documented link with high blood pressure runs through fatty liver. In a meta-analysis of 11 cohort studies with about 390,000 adults, people with non-alcoholic fatty liver disease were about 1.7 times as likely to develop high blood pressure over an average of almost six years (Ciardullo 2022), and higher blood pressure goes with more frequent and more severe fatty liver (Aneni 2015). These are associations, not proof of cause: both conditions share the same drivers, such as excess weight and insulin resistance.
Portal Hypertension and Systemic Effects
A specific form of high blood pressure related to the liver is portal hypertension, which occurs in conditions such as cirrhosis. Portal hypertension refers to elevated blood pressure within the portal vein, the vessel that carries blood from the digestive organs to the liver. Although this form of hypertension is localized to the liver, it has systemic effects, often leading to fluid retention in the abdomen (ascites) and lower extremities (peripheral edema). Portal hypertension does not raise the blood pressure measured on the arm; in advanced cirrhosis arm blood pressure is often low, because arteries elsewhere in the body widen.
Fluid Retention: The Role of the Liver
Fluid retention, or edema, is a common symptom of liver dysfunction, particularly in advanced liver disease (cirrhosis). Simple fatty liver does not usually cause swelling. The liver’s role in regulating blood proteins, such as albumin, is crucial for maintaining proper fluid balance. Albumin helps keep fluid within the blood vessels; when albumin levels drop due to liver disease, fluid leaks out into the surrounding tissues, causing edema.
The liver also influences the body’s ability to balance electrolytes, particularly sodium and potassium, through the production and breakdown of various hormones. When liver function is compromised, this balance is disrupted, leading to excessive sodium retention, which causes the body to hold onto more water, which shows up as swelling of the legs and fluid in the abdomen (ascites).
Additionally, liver dysfunction can lead to increased levels of inflammatory cytokines and oxidative stress, which impair kidney function, further contributing to fluid retention. The renin-angiotensin-aldosterone system (RAAS), which is crucial for kidney function and fluid balance, is heavily influenced by the liver. In cirrhosis, this RAAS activation is a main driver of fluid retention.
Nutrients, Liver Function and Blood Pressure: What Is Known
Certain nutrients such as choline, inositol, methionine, and taurine take part in liver metabolism. None of them is a treatment for high blood pressure or fluid retention, and only choline has EU-approved health claims: it contributes to normal lipid metabolism and to the maintenance of normal liver function. If you would like to look at how we built LiverGuard around choline, the full formula is on the product page. Here is what research says about each:
- Choline: This nutrient is needed to export fat from the liver; a lack of choline causes fatty liver disease (FLD). There is no evidence that choline lowers blood pressure or reduces fluid retention.
- Inositol: Inositol is studied for its role in fat metabolism and insulin signalling, so far mostly in animal studies. An effect on blood pressure or fluid retention has not been established in humans.
- Methionine: Through cysteine, methionine is a building block of glutathione, and it is the source of SAMe, which the liver uses in many reactions, including making phosphatidylcholine. There is no evidence that it affects fluid retention.
- Taurine: This amino acid supports bile production, aiding the liver in fat metabolism. Taurine has also been studied for blood pressure: in a meta-analysis of seven small trials (103 people, 1–6 g a day), taurine supplements lowered blood pressure by about 3 mmHg on average (Waldron 2018). The trials were small and short, and an effect on swelling (edema) has not been shown.
Morning Fluid Retention and Liver Dysfunction
Puffiness of the face and eyelids is often more noticeable in the morning, because fluid redistributes while you lie flat; swelling of the ankles and legs is usually worse in the evening. Swelling that does not go away, or comes with a swollen abdomen or shortness of breath, needs a doctor’s check: it can come from the heart, the kidneys or the liver.
Conclusion
The liver’s role in regulating blood pressure and fluid retention is often overlooked but crucial for overall cardiovascular and metabolic health. Impaired liver function can lead to imbalances in hormone metabolism, electrolyte regulation, and detoxification processes, all of which can contribute to fluid retention, while fatty liver is closely associated with high blood pressure. In fatty liver, the steps that reduce liver fat, such as weight loss and regular movement, also help blood pressure. In cirrhosis, fluid retention needs medical treatment. Do not stop prescribed medicines, including blood-pressure tablets and diuretics, without your doctor.
Resources
- Scorletti, E., & Byrne, C. D. (2013). Omega-3 fatty acids, hepatic lipid metabolism, and nonalcoholic fatty liver disease. Annual Review of Nutrition, 33, 231-248. DOI: 10.1146/annurev-nutr-071812-161230
- Elsharkawy, A. M., Oakley, F., & Mann, D. A. (2005). The role and regulation of hepatic stellate cell apoptosis in reversal of liver fibrosis. Apoptosis, 10(5), 927-939. DOI: 10.1007/s10495-005-1055-4
- Ciardullo, S., Grassi, G., Mancia, G., & Perseghin, G. (2022). Nonalcoholic fatty liver disease and risk of incident hypertension: a systematic review and meta-analysis. European Journal of Gastroenterology & Hepatology, 34(4), 365-371. DOI: 10.1097/MEG.0000000000002299
- Aneni, E. C., Oni, E. T., Martin, S. S., et al. (2015). Blood pressure is associated with the presence and severity of nonalcoholic fatty liver disease across the spectrum of cardiometabolic risk. Journal of Hypertension, 33(6), 1207-1214. DOI: 10.1097/HJH.0000000000000532
- Ciardullo, S., Monti, T., Sala, I., et al. (2020). Nonalcoholic fatty liver disease and advanced fibrosis in US adults across blood pressure categories. Hypertension, 76(2), 562-568. DOI: 10.1161/HYPERTENSIONAHA.120.15220
- European Association for the Study of the Liver. (2018). EASL Clinical Practice Guidelines for the management of patients with decompensated cirrhosis. Journal of Hepatology, 69(2), 406-460. DOI: 10.1016/j.jhep.2018.03.024
- Waldron, M., Patterson, S. D., Tallent, J., & Jeffries, O. (2018). The effects of oral taurine on resting blood pressure in humans: a meta-analysis. Current Hypertension Reports, 20(9), 81. DOI: 10.1007/s11906-018-0881-z
- Zeisel, S. H., & da Costa, K. A. (2009). Choline: an essential nutrient for public health. Nutrition Reviews, 67(11), 615-623. DOI: 10.1111/j.1753-4887.2009.00246.x
- Pani, A., Giossi, R., Menichelli, D., et al. (2020). Inositol and non-alcoholic fatty liver disease: a systematic review on deficiencies and supplementation. Nutrients, 12(11), 3379. DOI: 10.3390/nu12113379
- Mato, J. M., & Lu, S. C. (2007). Role of S-adenosyl-L-methionine in liver health and injury. Hepatology, 45(5), 1306-1312. DOI: 10.1002/hep.21650
