Inside your body: The liver

You hear a lot about the liver — that we need to regularly detox to keep it ‘clean’. But is there any truth to this? HFG nutritionist Claire Turnbull finds out, with help from liver experts Rachael Harry and Kerry McIlroy.

The more you get to know about the liver, the more amazing it seems. It is easily one of the busiest organs in the body, working day and night.

Liver facts

• The liver is the largest internal organ in our body (the skin is the largest organ overall).
• It is triangle-shaped, has two lobes and sits in the upper right-hand side of your body, usually up underneath your rib cage.
• The weight and size of the liver varies from person to person.
• Everything we eat, breathe and absorb is refined and detoxified by the liver.
• Liver cells can regenerate. They can recover well from a sudden injury, such as a paracetamol overdose, or even removal of a damaged part from, say, a car crash. But the liver doesn’t fare so well with chronic abuse, for example, excess alcohol over time can cause irreparable damage.
• Men’s livers do not process alcohol more quickly than women’s.

Jobs our liver does for us

Maintains normal blood sugar levels

Your liver uses carbohydrates as fuel. Carbohydrates not needed after eating, and not reserved in your muscles, can be stored by your liver and used later. The carbohydrate is altered and stored either as glycogen (carbohydrate), or triglycerides (fat).

In between eating, or when your body’s energy needs are high, your body breaks down these stored fuels to use as needed. This helps keep the amount of glucose (or sugar) in your blood steady, and the supply of fuel to the cells in your body within a stable range, regardless of whether you eat two or five times in a day.

Fat breakdown and metabolism

Each day the liver makes around 800—1000ml of bile, which acts a bit like dishwashing liquid, breaking down fat for absorption. Bile is also essential for the absorption of fat-soluble vitamins A, D, E and K.

Your liver also stores triglycerides, breaking them down to produce energy when needed. As well as storing and breaking down fat, the liver makes cholesterol along with little transporters called lipoproteins, which take cholesterol and triglycerides around your body (see The liver and cholesterol, below).

Protein metabolism

The liver breaks down proteins to make energy, or converts them into other types of fuels. As part of this process ammonia is made. Your liver converts this into urea, disposed of by your kidneys via your urine.

Processes drugs, hormones and toxins

The liver filters your blood, detoxifies alcohol and drugs, and breaks down or chemically alters toxins and hormones so your body can get rid of them. Toxins come from a variety of sources, including our environment, food and water, and the air we breathe.

Storage

As well as storing glycogen and triglycerides, the liver stores vitamins A, B12, D, E and K, and the minerals iron and copper. These are released by the liver when needed elsewhere in the body.

Activating vitamin D

The liver, skin and kidneys work together to make the active form of vitamin D.

Are we overloading our livers?

The liver can do far more than what most people require, and consultant hepatologist Rachael Harry says the idea the average person is ‘overloading their liver’ is incorrect.

“There are misconceptions that the liver somehow becomes clogged up and backs up with toxins and that we need to go on special detox or cleansing diets to clean the liver up, but there is no evidence that this is true,” Dr Harry, who specialises in liver disease, says. That said, you can still harm the liver by making poor lifestyle choices, causing conditions such as alcoholic liver and fatty liver diseases.

To keep your liver functioning at its best, make healthy choices throughout your life; don’t think a week-long detox will somehow make your liver ‘clean’ again.

Things that harm the liver include:

• being overweight
• type 2 diabetes
• high cholesterol

One, or a combination, of these factors can result in ‘non-alcoholic fatty liver disease’ (NAFLD), which is when fat accumulates in liver cells because there is more fat coming in than it can push out. NAFLD is now the most common liver disease in the world with around 85 per cent of obese individuals likely to have it.

Excess alcohol can, over time, also cause irreversible damage, as scar tissue is created in the liver, reducing its capacity to regenerate.

What can we do to keep our livers healthy?

The main thing you can do is manage your alcohol intake, according to liver specialist dietitian Kerry McIlroy. In New Zealand, many of us drink far more than is recommended as safe. We can also:

• maintain a healthy weight
• manage our blood pressure and cholesterol level
• eat a varied, balanced diet

If you have any concerns about your liver, speak to your GP who can pick up any abnormalities with a blood test.

New Zealand’s alcohol guidelines

• Women: No more than two standard units a day, and no more than a total of 10 in a week. At least two alcohol-free days.
• Men: No more than three standard units a day, and no more than a total of 15 total in a week. At least two alcohol-free days.

For more about alcohol and standard units, check out alcohol.org.nz.

The liver and cholesterol

• There are different types of cholesterol: good (HDL), and bad (LDL).
• A certain amount of cholesterol is necessary.
• Cholesterol measurement looks at the amount circulating in your blood.
• While some foods contain cholesterol, they have only a small impact on your blood cholesterol levels.
• A diet high in saturated fat can encourage your body to make far more of the unhealthy LDL cholesterol than it needs.
• Some people have a genetic predisposition to make too much cholesterol.

Go to heartfoundation.org.nz for more information on blood cholesterol.