Ever wondered what alcohol is doing to your liver? Most of us know that our glass of wine and our trusty blood cleansing companion are not the best of friends, but arming yourself with the knowledge of why may help inspire you to think twice before refilling your glass.
In basic terms, alcohol is a toxin to the liver. The reasons why are multiple. The main cause of damage, however, is from what is termed ‘oxidative stress.’ Oxidative stress occurs with an accumulation of free radicals overwhelms antioxidant defences. The damage can be so significant as to lead to alcoholic liver disease (ALD). There are thought to be many ways that oxidative stress can happen, and some of these will be explained here.
Acetaldehyde is the first breakdown product of alcohol in the body. This occurs in the liver via the enzyme, alcohol dehydrogenase. This toxic substance is then converted to acetate by acetate dehydrogenase. Some people have a deficiency in acetate dehydrogenase, which results in an excessive build up of acetaldehyde leading to ‘alcohol sensitivity.’ Symptoms may include facial flushing, increased heart rate, and increased blood pressure. Acetaldehyde may also be responsible for some of the symptoms associated with alcohol consumption, such as some of the behavioural effects. Even if you have a ‘normal’ ability to process this metabolite, it is still a reactive product that is likely to cause cellular damage. One mechanism is its ability to alter certain proteins, causing them to be inactive. It may also possibly cause an immune response against the liver.
Another factor thought to wreak havoc is the induction by alcohol of the liver enzyme CYP2E1. This enzyme belongs to a family of metabolising enzymes called cytochrome P450, and although it is important for breaking down alcohol, it creates toxic substances in the process. These include superoxide anion radicals, hydrogen peroxide and hydroxyl radicals. Damage can occur broadly throughout the cells, interrupting multiple cellular functions.
A little known property of the mineral iron is that it can also cause oxidative stress under certain conditions in the body, and you guessed it, alcohol plays a role in this, too. There appears to be more iron in the livers of those with a high alcohol intake or signs of alcoholic liver damage. Iron plays a destructive role by converting less reactive oxidants into more powerful oxidants.
Some of the other main ways that alcohol can affect our livers include: the alcohol induced production of free radicals by Kupffer cells in the liver; alcohol induced lack of oxygen in cells; and a reduction in antioxidant enzymes and substances. It is important to realise that many of these mechanisms feed into each other, potentially causing accumulative effects.
References available on request