What the Fruc(tose)?

04/12/2015 17:39 GMT | Updated 04/12/2016 10:12 GMT

I've been hearing a lot of people talking smack about fruit lately, so I wanted to clear some things up. Among other things, I hold bloggers and celebrity wellness personalities (with questionable nutrition qualifications) accountable for spouting a lot of crap that propagates the notion that certain fruits are "too high in sugar" and should be cut out of the diet.

For example, one famous blogger, said we should cut back on bananas on the basis of their high glycaemic index, and almost in the same breath, recommends eating dates and sweetening things with date syrup. Dates, on a per serving basis, have a glycaemic load higher than a banana (it also showing a fundamental misunderstanding of the problems of using glycaemic index vs. load, but I digress).

We have to remember that looking at glycaemic load & index are only one metric by which to measure the healthiness of a food and are not necessarily the best. For instance, they don't consider other health effects of that food. We also have evidence to suggest that bananas may actually improve glycaemic control in the long-run!

Another blogger giving fruit a bad rap is on a mission to vilify tropical fruits, like mangoes, on the basis that their sugars are released too quickly into the blood stream. Quel horreur! Too bad she missed this study which showed that, even in powdered form (with the fibre decimated) mangoes, like bananas, may help improve blood glucose control. They're also a really good source of the powerful antioxidant beta-carotene, which has a whole host of health promoting benefits (another reason we shouldn't focus too much on glycaemic index/load).

You see, fruit is much more than the sum of its parts. There are the obvious things - the fruit sugars, the fibre, vitamins, and minerals. But there are also thousands and thousands of compounds unique to plants that scientists are only beginning to get their heads around. For instance, the aforementioned mangoes, have a compound in them called mangiferin, which may slow the uptake of glucose into the blood stream. Similarly, berries have been shown to reduce the insulin response after a meal; berries have a cocktail of compounds: ellagitanins, anthocyanins, proanthocyanidins, soluble fibre, and a variety of other phytonutrients (i.e. plant nutrients) that all contribute to this effect, plus may help protect against heart disease and cancers. By only focussing on one nutrient, we're doing ourselves a massive disservice.

We know that countries who eat the most fruits and vegetables are the healthiest, so why are some bloggers (and the masses of Instagram followers who take their word as gospel) getting so amped up about fruit?

Earlier this year, the World Health Organisation called for countries to limit free sugars - ones that get added to food by manufacturers and by consumers at the table - to less than 10% of calories, or even better, to less than 5% of calories. This is of course a really important public health message; excess sugar leads to excess calories, leads to all sorts of problems - heart disease, obesity, and diabetes (although sugar is only part of the story in all of these conditions - just to keep things simple, you know?)

But people are getting this message confused and wrongly identifying fruit sugar as added sugar. It's not added, it was always in the fruit.

Another source of confusion is a body of literature that suggests fructose - one of the sugars found in fruit - is associated with liver damage akin to that of drinking excessive alcohol - a condition known as Non Alcoholic Fatty Liver Disease. NAFLD is a precursor to type two diabetes and other metabolic disorders. What we need to make clear though, it that this body of literature is again referring to added sugars (in the form of sucrose (table sugar), and high fructose corn syrup) not fructose found in fruit. In fact, one study found that a weight-loss diet which contained fructose in the form of fruit, was more effective, than a diet providing the same number of calories but no fructose. Another study showed that industrial, not naturally occurring fructose in fruit, was responsible for liver damage.

Let's get one thing clear - fruit contains sugar - but so do lots of healthy foods - beans, vegetables, whole grains - all contain sugar. Even blogger's beloved quinoa has a glycaemic load higher than the grapes they go to such lengths to avoid! The difference is that sugar from whole foods gets released into the body slowly and evenly, whereas added sugar gets in very quickly, and our pancreas needs to work really hard to bring it back down again. If this happens frequently, our pancreas can struggle to produce enough insulin, and over time, this can lead to type two diabetes.

Sugar, in the form of glucose, is what our bodies run on. We literally need it to fuel our cells and well, live. The problem is when sugars are refined and processed outside of the context of the food they naturally occur in. The best example of this is table sugar - or sucrose. It doesn't look much like the sugar cane it grew up in - the fibre, nutrients, and other phytochemicals that make up the plant have all been stripped away, leaving the white stuff behind. It then gets added back to food, which in itself is pretty devoid of nutrients - think breakfast cereals, bread, and other highly processed foods. Even fruit juice, which has the fibre, and other nutrients stripped away caused a spike in blood glucose, followed by such a big blast of insulin to get the sugar out of the blood stream that it causes blood glucose levels to dip. It's the same thing that happens after a 3pm chocolate bar at your desk; a sugar rush, followed by a crash. In fact, fruit juice has been linked to type two diabetes too.

But fruit juice is not the same as whole, unprocessed fruits. Just as white rice and wholegrain brown rice are not the same. A good diet is one that's rammed full of plant based, whole foods, like fresh or frozen vegetables, beans & pulses, whole grains, some nuts and seeds, and yes, fruits!

Last word on bloggers - these are generally the same people who espouse the benefits of 'alternative' and 'unrefined' sugars; honey, maple syrup, agave, coconut sugar - sure, these sweeteners may be more 'natural' than table sugar. They may have slightly more nutritional value - but you'd have to eat a shitton to get any benefit. They are all still added sugars. It all looks more or less the same under a microscope, and it all behaves the same in your body; it has the same number of calories per gram as table sugar and does the same thing to your blood sugar.

Just eat the fruit.

Laura Thomas, PhD is a nutritionist & wellness advocate who uses evidence based practice to help people live healthier lives.