What sugar does to your brain
Kiwis eat on average 37 teaspoons of the world's sweetest drug a day. We should be eating six.
A teaspoon of sugar helps the medicine go down, but 20-plus teaspoons and you'll probably need some medicine.
A little added sugar is lovely. Too much affects waistlines and physical health, and mounting evidence shows it impacts our psychological and brain health too.
On average New Zealanders consume about 37 teaspoons of sugar each day.
New guidelines released by the World Health Organisation (WHO) recommend no more than about 12 teaspoons of added sugar a day (this doesn't include naturally occurring sugars in fruit, vegetables and milk).
In fact, for the greatest health benefits they suggest halving that and having no more than six teaspoons a day (there's about four grams in a teaspoon).
"We have solid evidence that keeping intake of free sugars to less than 10 per cent of total energy intake reduces the risk of overweight, obesity and tooth decay," WHO's Department of Nutrition for Health and Development director Dr Francesco Branca said. "Making policy changes to support this will be key if countries are to live up to their commitments to reduce the burden of noncommunicable diseases."
The trouble is we crave the sweet stuff and the trickle down effect of consuming more and more of it is that we suffer.
"Evolutionarily, our mesolimbic pathway [the brain's reward system] reinforces that sweet things provide a healthy source of carbohydrates for our bodies," Penn State University neuroscientist Jordan Gaines Lewis said.
"Fruit is one thing, but modern diets have taken on a life of their own.
"These added sugars are sneaky and unbeknown to many of us, we've become hooked. In ways that drugs of abuse, such as nicotine, cocaine and heroin, hijack the brain's reward pathway and make users dependent, increasing neuro-chemical and behavioural evidence suggests that sugar is addictive in the same way, too."
Consider that a bowl of "healthy" breakfast cereal with a low-fat fruit yoghurt and a glass of apple juice consists of 20 teaspoons of sugar.
That's before you've even had your sweet "treat" for the day, your healthy low-fat yoghurt snack (many brands have five or six teaspoons of added sugar in a serve) or added a couple of tablespoons of barbecue sauce (one tablespoon has two teaspoons of sugar in it) to your "healthy" dinner of steak and vegetables.
And forget about your sugar-drenched fruit drink with lunch.
"Over-activating this reward system kickstarts a series of unfortunate events – loss of control, craving, and increased tolerance to sugar," neuroscientist Nicole Avena explained in a TED-Ed video.
Gaines Lewis explains: "In short, this means that repeated access to sugar over time leads to prolonged dopamine signalling, greater excitation of the brain's reward pathways and a need for even more sugar to activate all of the midbrain dopamine receptors like before".
"The brain becomes tolerant to sugar, and more is needed to attain the same sugar high."
The cyclical spiral can do more than make us seek more.
One recent study out of UCLA found excess sugar consumption can mess with memory and learning.
Bingeing on the sweet stuff disrupts the ability to think clearly and proper synapse function.
"Our findings illustrate that what you eat affects how you think," said the study's author Fernando Gomez-Pinilla, a professor of neurosurgery at the David Geffen School of Medicine at UCLA.
YOU CAN STILL INDULGE, SOMETIMES
It's news so depressing that it makes me want to go and eat some gelato to feel better.
However, there is good news. Relatively.
Firstly, many of the studies are extreme. We don't have to be extreme, we just need to watch our consumption and be aware of the hidden added sugars.
Sticking to as much unpackaged, unprocessed foods as we can means there's room for a bit of gelato – or whatever your sweet poison is.
Secondly, it is possible to decrease the brain's tolerance of sugar and thereby reduce the rollercoaster effect it has on our brain and emotions.
Gaines Lewis recounted the experience of a friend, Andrew, who gave up sugar for 40 days and went through the whole gamut of withdrawal. After the 40 days, Andrew had overcome the worst, and had probably reversed some of his altered dopamine signalling, she wrote.
"I remember eating my first sweet and thinking it was too sweet. I had to rebuild my tolerance," he said, after the sugar-free period.
Or just leave the tolerance levels low and enjoy that little hit that little bit more.