Aside from the long standing knowledge that it rots our teeth, sugar is now thought to cause all manner of diseases from diabetes and heart disease to cancer and even ageing skin. So shouldn’t that mean we should be avoiding it like the plague?
Sugar is a form of carbohydrate (a mix of carbon, hydrogen and oxygen), which is primarily responsible for providing energy to our bodies so that we can move and function without tiring. There are three types; Monosaccharides (sweets (glucose), fruit (fructose), dairy (galactose)), Oligosaccharides (fibre), and Polysaccharides (starchy foods). Monosaccharides enter the bloodstream quicker than other types because they have only one unit (hence ‘mono’) so don’t take much work to break down.
The sugars first have to go via the liver, where they are either turned into glucose and go to the bloodstream, or get stored as glycogen. Insulin removes excess blood sugar and takes it to be stored in the cells (as fat). Too much sugar repeatedly, and insulin won’t be able to do its job properly, and a person becomes ‘insulin resistant’, in severe cases diabetic.
Fruit contains sugar, so due to the aforementioned negative effects of too much sugar, fruit has been demonised as contributing to the demise of health and increase in waistlines. But it’s not as black and white as that – fruit also contains an abundance of vitamins, minerals, antioxidants, and both soluble and insoluble fibre, all of which promote good health, and the fibre present slows down the digestion of fruit. In fact when it comes to problems with blood sugar, it appears sugar has no unusual effects whatsoever after all.
Professor and author Steve Pavlina did a raw food diet for 30 days as an experiment, consuming mostly fruit, monitoring his blood sugar, weight, blood pressure and other health measures throughout:
“I monitored my blood sugar using a blood sugar testing device, the same kind diabetics may use. It showed no discernible spikes in blood sugar throughout the trial whatsoever — absolutely none. In fact, my blood sugar remained incredibly steady throughout the trial. My highest blood sugar reading of the trial was 94, which is still medium-low. All that sweet fruit in my diet simply did not have any adverse effect on my blood sugar. Eating this way gave my blood sugar more consistency than ever. I couldn’t spike my blood sugar on this diet if I tried. Even eating 19 bananas in one day made no difference.” (source)
I think some of the confusion may have arisen due to the similar names between fructose and High Fructose Corn Syrup. The latter is a corn sugar that has undergone changes with enzymes, to make it higher in fructose, and sweeter. It is cheap, and often used in commercial sweet foods such as confectionary, cakes etc. (though less and less now that people are aware of the harm it causes and manufacturers seek alternative options).
The nature and abundance of high fructose corn syrup in Western diets has been linked to obesity, cardiovascular disease, diabetes, and non-alcohol fatty liver disease. It is unclear whether it does this more than other simple sugars like ‘table sugar’, but needless to say, it’s just sugar, and too much sugar isn’t good for anyone.
Sugar is sugar, and too much of it is going to be a problem. But any food in the wrong amounts isn’t good, that includes fat, sugar, or protein. It’s just that sugar is both very easy to overeat and abundant in so many foods we have available.
And when it comes to fruit, fruit also contains both soluble and insoluble fibre to slow absorption. It would take a lot of fruit – more than most people eat, to have negative impact on health due to imbalanced blood sugar levels. Research shows 50g is about the amount of sugar the liver can process before negative effects may start to occur, so that’s at least 7 generous servings of averagely sweet (some fruits have more sugar than others) fruit per day, based on most fruits having about 7g fructose / 100g. However as Steve Pavlina’s study shows, this is far from being a given number for everyone.
Caveat; dried fruit and fruit juice are concentrated sources of fruit sugar, so while on occasion won’t hurt (and do have their own health benefits like vitamins and fibre), they’re best kept to a minimum – stick to fresh or frozen most of the time.
And as for weight gain and fat storage, this cannot occur unless there is a calorie surplus overall in a person’s diet, whatever foods those calories come from.