FATTY LIVER DISEASE

Besides the unique human brain, the liver is the next most complex organ in the human body.  The liver is a workhorse and is involved in a magnitude of functions, such as the processing of nutrients from all we ingest;  converting them into fuel, storing energy, while making essential proteins, such as blood clotting factors that help prevent blood loss. The liver is also the main detoxification site in the body as it filters harmful substances from your blood and renders them harmless after breakdown. 

However, a danger is that when things start to go awry in the liver, there are no noticeable symptoms.  By the time symptoms appear such as feelings of tiredness, experiencing discomfort, or pain in the upper right side of the abdomen, abdominal swelling and yellowing of the skin and eyes, it could be a sign of fatty liver disease.

What is fatty liver disease?

When the body produces too much fat or is unable to metabolize fat efficiently, excess fat is stored in the liver cells, where it accumulates.  Small amounts of fat in the liver is normal, but an increased build-up of fat (more than 5% of the liver’s weight) can cause inflammation, which can damage liver cells and create fibrosis or scarring.  In severe cases fibrosis can lead to cirrhosis and liver failure. 

In mild cases fatty liver disease will not prevent the liver from functioning normally, but in up to 30% of cases, the disease can get worse over time.  In those instances, the disease progresses through stages – an initial build-up of fat (reversible damage), followed by the liver becoming inflamed and swollen, causing damage to the liver tissue, and forming scar tissue (an irreversible process called fibrosis).  During the final stage, extensive scar tissue replaces healthy tissue, a condition called cirrhosis of the liver (irreversible).  The hard scar tissue slows down liver functioning and may eventually block the functions of the liver entirely, leading to liver failure, while posing an increased risk for cancer of the liver.

Types of fatty liver disease:

There are two main types of fatty liver disease:

• Alcoholic fatty liver disease (AFDL) refers to the damage done to the liver due to the excessive consumption of alcohol. The liver breaks down most of the alcohol you drink, to allow it to be removed from the body. The process of breaking the alcohol down can generate harmful substances (e.g. acetaldehyde), which can damage liver cells and promote inflammation in the liver.  The liver has the ability to develop new cells, but prolonged alcohol misuse over many years, can reduce the liver’s ability to regenerate.  Fatty liver is the earliest stage of alcohol-related liver disease. The next stages are alcoholic hepatitis and cirrhosis of the liver.

• Non-alcoholic fatty liver disease (NAFLD) is increasingly common around the world, especially in western nations.  In the US at present it is the most common form of chronic liver disease, affecting about 25% of the population.  NAFLD can go on to develop into a more aggressive form, known as Non-alcoholic steatohepatitis (NASH), which is marked by liver inflammation, and may progress to advanced scarring or cirrhosis and liver failure.  The damage is similar to the damage caused by heavy alcohol use.  Several risk factors have been associated with this form of the disease.

Risk factors for non-alcoholic fatty liver disease (NAFLD):

Several risk factors can make it likely to develop non-alcoholic fatty liver disease, such as:

• A high intake of specifically fructose, from sugar and sweetened food and beverages, is associated with insulin resistance, diabetes, obesity, and fatty liver disease.  Sugar consists of glucose – which fuels every cell in the body and which levels are constantly controlled in the body, mainly through the hormone, insulin – and fructose – which is taken up 100% by the liver.  Liver cells, if flooded by fructose, converts most of this monosaccharide to fat, called triglycerides.  Some of this fat is exported by the liver in the form of very low-density lipoprotein (VLDL), and reflected by rising triglyceride levels in the bloodstream.  However, most of this fat is deposited in liver cells and with continued intake of fructose, results in a fatty liver. Other products also formed in the liver during fructose metabolism are uric acid and damaging free radicals. 

• A high fructose intake is also linked to high blood sugar levels and insulin resistance (associated with increased fatty acid levels in the blood), which is a precursor to diabetes.  Having insulin resistance, prediabetes and type 2 diabetes are all risk factors for developing fatty liver disease.  These conditions are linked to obesity, but weight loss, which makes the fatty liver less fatty, can reduce the risk of fatty liver disease.  However, rapid weight loss through crash dieting can end up possibly damaging the liver.

• Pregnancy may cause fatty liver disease, which is a rare, but serious complication of pregnancy.  Liver health usually returns to normal within a few weeks of giving birth.

• Infections such as hepatitis C can cause fatty liver disease.

• Side effects from certain prescription medications may result in fatty liver disease.

• Exposure to certain toxins that the liver is unable to break down can cause fatty liver disease.

• The risk of dying from cardiovascular disease is twice as high if you have fatty liver disease, as the affected liver produces inflammatory factors that can lead to narrowed blood vessels.

• Eating large quantities of unhealthy fats, such as saturated and trans fats, can lead to high levels of fatty substances, such as cholesterol and triglycerides, in the blood stream.
• A genetic predisposition and a family history of fatty liver disease is a rare, but definite risk factor for fatty liver disease.

How to reduce your risk of NAFLD:

• Choose a healthy daily diet, with at least two-thirds of your plate at each meal plant based – rich in vegetables, whole grains, healthy fats, and fruit.

• Maintain a healthy weight by choosing a healthy diet and regular exercise.

• Exercise enough to work up a sweat, most days of the week.

• Avoid sugar, sodas, and fruit juices 

• Minimise alcohol intake

• Avoid snacking between meals

• Avoid seed oils high in omega 6

Functions of the liver:

The liver has two major sources of blood – the portal vein brings in nutrient-rich blood from the digestive system, and the hepatic artery carries oxygenated blood from the heart.  These blood vessels divide into small capillaries in the liver, with each ending in a lobule. Lobules are the functional units of the liver and consist of millions of cells called hepatocytes.  Blood is removed from the liver through three hepatic veins.

The liver plays an important role in the body:

• The liver’s main function is to filter (detoxify and purify) the blood coming from the digestive tract (stomach and intestine).
• The liver processes this blood and breaks down, balances, and creates nutrients for the body to use.
• It secretes a clear yellow or orange fluid called bile, which helps to carry away waste and helps the small intestine to digest and absorb fats, cholesterol, and fat=soluble vitamins. (Bile consists of bile salts, cholesterol, bilirubin, electrolytes, and water.) 
• When the liver has broken down harmful substances, they are excreted into either the bile or the blood. Bile by-products enter the intestine and ultimately exit in bowel movements, while blood by-products are filtered out by the kidneys and exit in urine.
• It metabolizes (breaks down) medicines into forms that are easier for the body to use.   It also clears the blood of medicines and harmful substances.
• Makes cholesterol and special proteins to help carry fats through the body.
• It regulates blood clotting.  Vitamin K is necessary for the creation of certain coagulants in the liver that help clot the blood, while vitamin K needs bile for its absorption. If the liver does not produce enough bile, clotting factors cannot be produced.

• It has an immunological function, as the liver is part of the mononuclear phagocyte system. It contains high numbers of Kupffer cells that are involved in immune activity, through destroying any toxins that might enter the liver through the gut.

• Carrying out the metabolism of the absorbed products of the three major macronutrients in our diet – carbohydrates, fats, and proteins, following digestion in the gut.  Bile breaks down fats and makes them easier to digest.    Excess glucose is stored as glycogen in the liver and released whenever additional energy is needed.  The liver plays a major role in amino acid metabolism – both for the making of new proteins (anabolism) and the catabolism of amino acids.

• It stores vitamins and minerals.  Excess dietary intake of fat-soluble vitamins A, D, E, and K are stored in the liver and in fat cells. Vitamin B12 is the only water-soluble vitamin that is stored in the liver.  Other water-soluble vitamins, such as vitamin C and the other B vitamins need to be replenished daily, as they are not stored in the body.  The liver stores iron from hemoglobin in the form of ferritin, ready to be used to make new red blood cells. The liver also stores and releases copper as needed.

• It produces albumin, which is the most plentiful protein in blood serum. Albumin transports fatty acids and steroid hormones and helps maintain the correct osmotic pressure to prevent the leaking of blood vessels.

• It is responsible for excreting cholesterol, hormones, and bilirubin (a yellowish substance that forms in the blood after red blood cells break down). (Too much bilirubin makes skin and eyes turn yellow.)  Bilirubin is formed by the breakdown of hemoglobin. The iron released from hemoglobin is stored in the liver or bone marrow and used to make the next generation of blood cells.  (Hemoglobin is the protein molecule in red blood cells that carries oxygen from the lungs to the body’s tissues and returns carbon dioxide from the tissues back to the lungs.)

Looking after your liver:

The liver is a very forgiving organ – after a good party where the booze was flowing freely, the liver will regenerate itself to undo the damage, but it takes two weeks of no alcohol to do so!  The same applies to overloading the body with sugar and unhealthy fats on the rare occasion.  Help the liver cope by limiting alcohol intake to one drink a day, while eating real food and avoiding all processed food and sweetened drinks.  The Mediterranean pattern of eating is the healthiest, most balanced and sustainable way of daily nutritional choices.

Sources:

Everything you need to know about fatty liver.  Published online and updated 12 February 2020.  Healthline.  (www.healthline.com)

Fatty liver disease.  Published online and updated 23 July 2020.  Medline Plus.  US National Library of Medicine.  National Institutes of Health.  (www.medlineplus.gov)

Fatty liver disease.  Published online and reviewed 31 July 2020.  Cleveland Clinic USA.   (www.clevelandclinnic.org)

Is fructose bad for you?  Published online and updated 6 March 2020.  Harvard Health Blog.  Harvard Medical School.  (www.health.harvard.edu)

When the liver gets fatty.  Published online and updated 9 May 2018.  Harvard Health Letter.  Harvard Medical School.  (www.health.harvard.edu)

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