Why are so many scientists studying this spice?
Paula Goodyer | Fairfax Media | The Age | May 10 2017
What do depression, dementia, diabetes, heart disease, arthritis and cancer have in common - apart from being modern plagues? They're linked by inflammation - not the acute painful inflammation that erupts from a throat infection and then subsides, but the chronic inflammation that smoulders in the body and is linked to many chronic diseases.
But what if there were an antidote - a natural anti-inflammatory that could turn inflammation down without the harmful side effects of anti-inflammatory drugs?
Curcumin is a leading candidate for the job. An ingredient of the yellow spice turmeric, its anti-inflammatory effect has prompted around 150 research projects here and overseas looking at its potential to prevent or improve a range of problems including autism and inflammatory bowel disease as well as common conditions like depression and diabetes.
People with depression have higher levels of inflammation - and inflammation reduces the effect of serotonin, a brain chemical that regulates mood, explains Dr Adrian Lopresti whose research at Perth's Murdoch University found that both curcumin or a combination of curcumin and saffron - another yellow spice - have a similar effect to anti-depressants.
"The people in our research had moderate chronic depression. We found that, compared to a placebo, they had a greater benefit from these supplements including those who were already on anti-depressants." he says. "Pharmaceutical anti-inflammatories can improve depression too - but they have side effects."
"Curcumin is also an antioxidant which helps prevent free radical damage -studies have found that people with depression have greater free radical damage to brain cells. Curcumin appears to help protect brain cells - which is why other studies are looking at whether curcumin might help prevent dementia."
Inflammation can also damage the cells in the pancreas that produce the insulin needed to keep levels of blood glucose healthy, says Professor Manohar Garg* from the University of Newcastle's Centre for Physical Activity and Nutrition in NSW. He's running two studies - one to see if curcumin reduces inflammation in people with prediabetes; another to see if curcumin can help people diagnosed with type 2 diabetes from developing heart disease too.
"There's a huge demand for an anti-inflammatory substance that doesn't have side effects and curcumin stands out. "
Then there's cancer.
More than 60 studies of curcumin worldwide are looking at its potential role with a number of cancers, says Dr Gunveen Kaur from Deakin University's Institute for Physical Activity and Nutrition.
"But these studies are mostly small - there's a need for more large scale studies," she says.
One clue that sparked interest in curcumin is that in India, where turmeric consumption in foods like dahl, curries and pickles is high, the levels of some chronic diseases including dementia and cancer have been lower than in the west.
That's now changing as India embraces western fast food, Professor Garg says.
"People are eating more burgers, pizza and noodles. Consumption of traditional foods containing turmeric is dropping, with parallel increases in cardiovascular disease, type 2 diabetes and cancer. That's not to say the drop in turmeric consumption is the only cause but the two trends are parallel."
Meanwhile in Australia, more baristas are lacing lattes with turmeric - and you can even buy turmeric chips. But neither option will deliver a significant dose of curcumin, Professor Garg says.
"It has a very short life in the blood so unless you're eating it regularly - as in a traditional Indian diet which might include turmeric at lunch and dinner - it's difficult to maintain blood levels of curcumin," he says.
Curcumin's bioavailability - the ease with which it reaches the body's tissues - can be a problem because the body processes it quickly and excretes it, he adds. It's more bioavailable when combined with fat - as in food cooked with oil - and with piperine, the ingredient in black pepper that gives it flavour.
Piperine slows down the metabolism of curcumin, explains Dr Kaur - one study in humans found that combining 2 g of curcumin with 20 mg of piperine increased curcumin's bioavailability by 2000 per cent."
But while we wait for science to figure out what curcumin can and can't do, some people are jumping the gun and opting for curcumin injections - the death of a woman in California earlier this year has been related to intravenous curcumin.
"I don't see any strong evidence to suggest that IV injections will cure disease - and we don't fully understand the effects of bypassing the gut or know in which of the body's tissues or in what doses curcumin might cause toxicity," stresses Dr Kaur whose report card on curcumin appeared in The Conversation recently.
"There are many other risks of IV injections including infection or accidentally injecting air in the veins which can be fatal."
If you want to try a curcumin supplement how do you choose a good one?
With difficulty - there's no reliable way to tell if a supplement is effective and contains what it claims to contain, she says.
"We have an online registry of supplements called the Australian Register of Therapeutic Goods maintained by the Therapeutic Goods Administration (TGA). Although the TGA monitors the safety of supplements, it relies on the manufacturer's honesty to declare the ingredients of a supplement and does not actually test the supplements.
"Many supplements sold on the internet are not registered with the TGA and therefore not regulated in any way."
Until we know more, her advice is to take curcumin in food as part of a healthy diet.
More dahl anyone?
*Professor Garg is recruiting volunteers in the Hunter area of NSW diagnosed with either pre-diabetes or type 2 diabetes to take part in research into curcumin. For more information, call (02) 4921 5636.