eli5: sugar and what’s bad and what isn’t?



Sugar is in fruit and you can eat a ton of fruit and be ok, but then you can’t eat much candy or pop. What’s the difference? Also sugar vs sweeteners? Sugar is such a world I can’t wrap my mind around because there’s so much debate!

In: Biology

Basically, sugar is sugar, the source and type don’t matter much but the amount does.

As long as your having a healthy amount as part of a balanced diet the type isn’t that important.

But if you want to know there’s 3 types of sugar, Glucose, Fructose, and Galactose.
All sugar is comprised of some combination of three different sugar molecules, in various ratios.

White sugar is 50% glucose and 50% fructose.

Maple syrup is 51.5% glucose and 49.5% fructose.

High fructose corn syrup is 45% glucose and 55% fructose.

Agave nectar is 12% glucose and 88% fructose.

Brown sugar is 49.5% glucose and 49.5% fructose.

Honey is 44.5% glucose and 50.5% fructose.

Coconut sugar is around 80% sucrose, which breaks down to around 40% glucose and 40% fructose.

It’s pretty safe to say that we’re splitting hairs when we say that one sugar is better chemically than another, since they’re all pretty much the same chemically, and to our bodies.

Non-nutritive sweeteners work by mimicking the shape of sugar, but being chemically different enough that they can’t be absorbed. So your taste buds are fooled, but the receptors that absorb sugar are not. Many of them (the ones that end in -ol, like xylitol) have an extra -OH group added, which stops them getting absorbed.

The difference between (for example) eating an apple or orange, and eating the exact amount of sugar in them is that you’re missing out on lots of other useful dietary substances. Even just the water, but also fibre and vitamins.

Imagine how full you’d be after eating a big bowl of oranges, vs a big bowl of Kit Kats. But the oranges have (per google) 9 grams of sugar per 100 g, and the Kit Kats have 49 g of sugar per 100 g. So when you eat an orange, 91% of it isn’t sugar (and one orange has your daily minimum of vitamin C). And when you eat a Kit Kat, almost half of it is just sugar.

As someone has already mentioned glucose and fructose are the main sugars we talk about and table sugars tend to be sucrose which is a combination of them. I am no expert but it does seem like there are *some* differences in the way that the body metabolises different sugar and the sort of fat that might result or where that fat is produced. Fructose is as a matter if interest the ‘sweeter’ of the two.

The problem with sugar is much to do with quantity and ‘context’. Too much sugar is associated with obesity , diabetes and dental cavities. Obesity is *associated* further with things like heart disease and cancer. Though sugar does have some role in making you feel full, I believe, on its own it does so less than when combined with other important nutrients. When you eat fruit the sugar is combined with other useful nutrients and things like fibre that help slow down the sugar uptake and make us feel full, if you eat sweets or drink soda then this isn’t the case and you are more likely to still feel hungry.

As far as sweeteners are concerned , it’s seems like studies will continue to be ongoing ( and there are of course different ones).I have read that people drinking soda with sweetener in are again likely to want to eat more and thus it’s not necessarily as helpful as people might think in dieting. As far as any other health issues with sweeteners it’s difficult because there will be some scaremongering that might have no clear research basis. On the other hand, I’m not sure whether the amount that people now have with them being so common was quite expected.

I think that it wouldn’t be unreasonable to consider whether like sugar itself you should consider the whole nutritional value of whatever you are eating or drinking , whether having unnecessary *added* sweetness is likely to be a good thing and whether it’s sometimes better to have less of something than always try to find a replacement. But to be clear I am not aware of any research that shows sweeteners are ‘bad’ for you unless someone knows better…

The difference between the sugar in fruit and the sugar in candy or pop is how it’s packaged. The sugar in fruit is mostly contained in the cells of the fruit, and this means two things. One, not all of the sugar is available for your body to absorb, because chewing doesn’t break open every cell, and our digestive system can’t break down intact plant cells. Two, when you eat fruit, you’re eating a bunch of other stuff with it, namely the soluble fibre that slows down your body’s absorption of the sugar.

Candy, on the other hand, is refined sugar, that is, sugar that’s been stripped of its natural plant packaging. This means that all of the sugar in candy is readily available, and there’s nothing else with it to slow down the absorption, so you get a massive spike in blood sugar (which is generally bad).

Artificial sweeteners are something else entirely. In pretty much every case, the shape of the sweetener molecule is similar enough to that of sugar that it can fit into the bits of your tongue that taste sweetness, tricking your body into thinking there’s sugar there. For “natural” sweeteners like xylitol and other sugar alcohols, your body can still break them down for energy, but for artificial sweeteners like aspartame, your body can’t break them down, so you get the sweet taste without calories (which is a whole separate issue).