• Dr Michael Mosley explores if a glass of red wine can protect you against the harmful effects of junk food. (Supplied )
Dr Michael Mosley investigates claims suggesting that drinking antioxidant-rich drinks, like red wine and green tea, helps to protect against the harmful effects of junk food.
By
Yasmin Noone

8 Mar 2019 - 9:23 AM  UPDATED 14 Jan 2020 - 2:01 PM

Those among us who love a good drop of red wine may be guilty of touting the beverage’s health benefits in the bid to have an extra glass with dinner.

After all, red wine has been celebrated as a healthy drink full of antioxidants with positive effects on your heart and cardiovascular health.

It’s also been believed that the antioxidants in red wine fight the nasty free radicals found in the fatty meals we eat. But now the Trust Me I’m A Doctor team claims otherwise.

What is a free radical and why is it so nasty?

Red wine, green tea and orange juice are all packed with good substances called antioxidants, which are said to protect your body against the ravages of free radicals produced by junk food. 

As Dr Mosley explains in episode two of Trust Me I’m a Doctor, free radicals are substances that our bodies produce within hours after eating a high fat, high sugar meal. 

“They change cholesterol and make it more likely to clog your arteries,” says Dr Mosley. “They also make blood vessels less flexible, an effect that can last for several hours. And repeatedly having fatty foods increases your risk of developing serious cardiovascular problems.”

On the other hand, an antioxidant is a substance found in certain foods that possibly prevent the damage caused by free radicals by inhibiting oxidation.

“The simplistic theory is that antioxidants mop up free radicals and what we're looking to see is whether, antioxidants in our diet, taken at the same time as the junk food, can prevent those harmful effects."

Antioxidant-rich drinks v free radicals

Dr Mosley visits the UK’s University of the Highlands and Islands to test the long-held belief that consuming an antioxidant-rich drink, like red wine, alongside a fatty meal, negates the impact that junk food has on our blood vessels.

He observes an experiment led by Professor Ian Megson, a cardiovascular scientist, to determine whether antioxidant-rich drinks really do destroy free radicals in fatty foods.

“The simplistic theory is that antioxidants mop up free radicals and what we're looking to see is whether, antioxidants in our diet, taken at the same time as the junk food, can prevent those harmful effects,” Prof Megson tells Dr Mosley.

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Healthy volunteers are recruited to eat a high-fat meal each day accompanied by an antioxidant-rich drink – red wine, green tea or orange juice.

The team measure two factors: the flexibility of the volunteers' blood vessels, and their levels of a substance called ‘oxidised cholesterol’ that affects the health of the arteries.

Ultrasound scans are taken before and after each meal to measure the flexibility of participants’ blood vessels. Blood tests samples are also taken to test their levels of oxidised cholesterol.

The results showed that eating a high-fat meal reduced the flexibility of the participants’ arteries by 30 per cent. None of the drinks consumed – not even red wine – had any positive effect on blood vessels.

“And when it comes to claims around antioxidants, do be sceptical. Just because it says it's rich in antioxidants doesn't mean it's going to do you any good.”

“The only thing that there was a slight impact on was with the orange juice,” says Prof Megson. “Unfortunately it made it slightly worse if anything. There's more sugar in orange juice, it might be the sugar that causes more free radicals to be produced rather than the antioxidants preventing free radicals.”

The study also showed there was no impact on oxidised cholesterol levels from any of the antioxidant drinks.

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So why have we always believed that drinking red wine and green tea – drinks that are rich in antioxidants – can balance out the damage of a fatty meal?

“We know that countries that have a lifestyle that involves drinks and foods high in antioxidants have a lower incidence of cardiovascular disease and that's really where the whole story started from," says Prof Megson. "But, it's most likely the lifestyle as a whole that is responsible rather than the antioxidants [in red wine, green tea or orange juice.]”

Dr Mosley explains that even though this study was small and only short-term, other long-term studies show that “some benefit to cardiovascular health in the longer term, but even in those studies it's not clear if the effects were purely down to antioxidants”. 

“Sadly whatever it is you drink, it's unlikely to counteract the effects of a junk food diet,” says Dr Mosley.

“And when it comes to claims around antioxidants, do be sceptical. Just because it says it's rich in antioxidants doesn't mean it's going to do you any good.”

The three-part series of Michael Mosley:Trust Me I’m A Doctor airs 8.30pm, Monday nights on SBS and streams via on SBS On Demand after broadcast. Watch Episode 2 here.

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