Who doesn’t like chocolate? Very few of us. And a new study brings good news for those of us who like eating it – with a small caveat: you may need to learn to enjoy it differently.
A study led by Professor Joshua Lambert at Penn State University in the United States has found that feeding cocoa powder to high-fat-fed mice with liver disease significantly reduced the severity of their condition.
That alcohol is bad for our livers is well known. But few people understand that livers can become damaged even in those who abstain from drinking. Fatty liver disease is nicknamed “the most common disease you’ve never heard of”: one in four people have it, more than sufferers of diabetes and arthritis combined.
Dr Paul Ng, a Hong Kong specialist in gastroenterology and hepatology, says the condition is “linked to affluence; an abnormal accumulation of fat in liver cells because of excessive nutrition being stored inside the body”. In Hong Kong, 27 per cent of the population is estimated to be living with the condition, a figure that is on the rise.
Joshua Lambert is a professor at Penn State University in the US.
Mild cases are usually harmless, says Ng. But more serious cases can kill, “typically from a heart attack or stroke, as these patients run higher risks of having coronary heart disease”, he says. Happily, the condition is curable, Ng says – “not by a doctor but by the patients themselves”.
At least 60 per cent of patients with fatty liver can recover through lifestyle changes. That might include having more cocoa, like the fat mice in Lambert’s study. But it is not quite that simple.
The consumption of chocolate, which contains cocoa solids, cocoa fat or both, has been associated with a reduced risk of cardiometabolic diseases including stroke, in part thanks to the plant chemicals known as flavanols. These have antioxidant, heart-protective properties, says dietitian Michelle Lau at Hong Kong’s Nutrilicious.
The flavanols in cocoa can improve blood flow to the brain by increasing nitric oxide levels, causing blood vessel walls to relax and dilate. (They may also have positive effects on memory and mood, because they accumulate in the brain regions associated with learning and memory, including the hippocampus.)
Lambert and his team wanted to dig further into chocolate’s health benefits. It made sense, explains Lambert, “to investigate whether cocoa consumption had an effect on non-alcohol-related fatty liver disease, which is commonly associated with obesity in humans”.
Non-alcohol-related fatty liver disease is commonly associated with obesity in humans. Photo: Shutterstock
The cocoa diet for mice was introduced to them when they were already plump. This allowed researchers to test cocoa’s protective effects on mice in a situation that is representative of our growing – literally – global model: we’re all getting fatter.
“Given the high proportion of people in the United States and other parts of the world with obesity [in Hong Kong, 30 per cent of the adult population are obese and another 20 per cent are overweight] there is a need to develop potentially effective dietary interventions rather than just preventive agents,” said Lambert.
But how does the cocoa work, and how does it safeguard the liver?
Lambert explains: “There is a lot of evidence that the liver protective effects are because of the phytochemicals in cocoa: polyphenols. These compounds have antioxidant actions, but they have other biological effects as well. Since we used cocoa powder in our study, which contains other things – fibre, for example – we can’t say for sure if the benefits shown were due solely to the polyphenols. But they likely play an important role.”
He says polyphenols can reduce or moderate fat and carbohydrate digestion and its availability in the small intestine. “Earlier studies showed cocoa polyphenols can inhibit pancreatic lipase, the enzyme that breaks down fat during digestion, and that cocoa can increase the levels of fat that end up in faeces. Combined, this data suggests that cocoa polyphenols can reduce fat digestibility and absorption.”
We don’t know if cocoa consumption can aid in weight loss, he says. “In our study, the cocoa-treated mice stayed on the high-fat diet, so it’s possible that the treatment just kept things from getting worse,” says Lambert.
There is data suggesting that non-chocolate foods such as green tea, blueberries and cinnamon have similar effects on obesity and obesity-related fatty liver. Photo: Shutterstock
His team believes cocoa’s liver protective elements result from both the reduced fat digestibility in the small intestine caused by those polyphenols, and from improved gut barrier function and reduced gastrointestinal inflammation, which leads to reduced inflammation in the rest of the body.
What if the mice just ate less because of the cocoa? Could it be an appetite suppressant? Lambert says no, there was no change in their appetite. They ate just as much high-fat food as their cocoa-free comrades. But – and this is the crux of the findings – cocoa-treated mice gained weight at a rate 21 per cent lower than regular-fat-fed mice and their livers contained 28 per cent less fat.
At the end of the cocoa diet, they also had smaller spleen weights – indicating less inflammation. Levels of oxidative stress markers were 70 per cent lower than the high fat-fed control mice and their livers indicated substantially lower levels of DNA damage – 75 per cent less than in the control group.
Substituting a mug of cocoa into the diet for some other fat/sugar-containing food might afford benefits
The study used a commercially available cocoa product at a “physiologically achievable dose”; that is, people could easily consume an equivalent dose. “Doing the calculations, for people it works out to about 10 tablespoons of cocoa powder a day,” Lambert says. That is about five mugs of cocoa based on the instructions on the average tin of cocoa powder.
I think about how I like to drink my one cup of cocoa on a winter’s evening: sweet, hot, creamy. And fat mice come to mind. There must be a leaner way to get what we need? Certainly, says Lambert, but there is a need for recipe development.
“It would be good if there were ways to incorporate cocoa into the diet in foods other than chocolate. The other way that we are looking at the results is in terms of substitution: our results suggest that substituting a mug of cocoa into the diet for some other fat/sugar-containing food might afford benefits,” Lambert says.
What other foods might have a similar effect? Lambert suggests green tea, blueberries, cinnamon and other items contain polyphenols similar to those in cocoa, and there is data suggesting that they have similar effects on obesity and obesity-related fatty liver.
Several studies in human subjects with fatty liver disease have seen benefits from these foods in terms of lowering oxidative stress in the liver and on vascular function. While these are promising studies, more work is needed, he says.
In the meantime, I’m off for a mug of hot chocolate: two heaped tablespoons of cocoa powder, skimmed milk and stevia to taste.