Binge drinkers may reduce their chance of developing deadly liver disease if they also smoke cannabis, a medical study has found.
The surprising results come from a 2018 study of 320,000 people who had a history of misusing alcohol, but scientists warn that some liver conditions are exacerbated by cannabis use and the drug does little to mitigate many of alcohol's other negative effects.
Of the people studied, 90 per cent had never smoked cannabis, 8 per cent smoked it occasionally and 2 per cent were dependent on it.
Both groups of cannabis smokers had a 45 per cent lower risk of getting "fatty liver disease" and a 55 per cent lower chance of developing cirrhosis - scarring of the liver.
Crucially, this group also had a 38 per cent lower chance of developing hepatocellular carcinoma, the most common liver cancer.
The researchers commented on their findings, published in the journal Liver International, saying: "While cannabis has demonstrated anti‐inflammatory properties, its combined use with alcohol and the development of liver disease remain unclear."
They noted that one cause for the results might be that receptors in the body that respond to cannabis can also suppress collection of fat on the liver.
The study's co-author Dr Terence Bukong told Healthline: "The primary aim of our study was to assess the impact of cannabis use and the development of alcoholic liver disease.
"Given that no clinical studies had previously evaluated the impact of cannabis use and the development of progressive stages of alcoholic liver disease in humans, we thought that this was an important research area which needed urgent investigation."
Bukong added: "Our findings revealed that cannabis users were less likely to develop alcoholic liver disease, and cannabis-dependent individuals were the least likely individuals to develop alcoholic liver disease."
He said his research group was now working to discover which compounds in cannabis were responsible for action on the liver and want to develop treatments for liver disease.
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Bukong told Healthline that he was confident that "specific formulations of cannabinoids might soon be used [to] prevent or treat liver disease. My research group is actively working on important cannabis formulations which we hope will be important drug leads for future testing in the prevention and treatment of liver disease from inflammatory, metabolic, and even viral causes".
Dr Hardeep Singh, a gastroenterologist at St. Joseph Hospital in Orange, California, sounded a note of caution on the findings, warning that one liver disease was made worse by cannabis use.
"Patients with hepatitis C who used cannabis had way more liver scarring than those who didn't and more progression of their liver disease. Something in the cannabis could actually be increasing fatty liver disease and fibrosis," he told Healthline.
Singh theorises that some people have sensitivity to cannabis that influences whether they can benefit from it or not. "You can't just tell the public marijuana is good for your liver, because there may also be people whose liver is harmed by it."
A study published earlier this year in the Lancet journal showed that Kiwis are drinking less than 20 years ago but are still binge-drinking regularly.
While older adults are still drinking hazardously, consumption among millennials is falling.
Alcohol Action New Zealand told the Herald in August that, in the past 10 years, alcohol has contributed to 8000 premature deaths, 700,000 physical and sexual assaults, up to 30,000 children born with alcohol-related brain damage and more than $70 billion of social costs.
Kiwis will get to have their say on the legal status of cannabis at the 2020 election, when a referendum will be held on a whether New Zealand open a regulated legal market for the drug.
A bill will be drafted before the 2020 election, but will not be passed into law.
The bill will aim to reduce cannabis-related harm by protecting young people - whose brain development can be harmed by frequent cannabis use - offering health services to those that need them, and weakening the black market that currently peddles unregulated products to whoever can buy them.