Tagatose is most commonly found in milk. And when I say ‘most commonly’, I mean ‘you have to break down the lactulose into smaller molecules and then rearrange the atoms of the smallest one until you get it’. So, not very common.

It is chemically virtually identical to ‘real’ sugar, because it is the chiral twin of L-fructose, but it doesn’t have the same effect on your body (i.e. the need to stop by your liver for a chat and a sit-down before being converted into fat). However, from what I have learned (and experienced) its behaviour is very odd.

Tagatose, although totally a sugar, tends to behave much more like a sugar alcohol. This is because it’s a chiral, or ‘right-handed’ twin of fructose; our bodies will only use left-handed sugars for energy, and they basically have no idea what to do with right-handed ones. Tagatose has around 30% the calorie impact of table sugar, but that’s because only a small amount of it is actually absorbed by your body; the rest passes straight through your intestine unabsorbed, much like a dietary fibre. And, much like other sugar alcohols, tagatose is hydrophilic, meaning it absorbs moisture. Keep these things in mind as you grit your teeth throughout the next terrifying paragraphs.


Chemically, tagatose is a sugar – a monosaccharide (like glucose or fructose), but is the right-handed chiral twin (or mirror image) of fructose. Unlike virtually every other sweetener I have reviewed, tagatose is the only genuinely reducing sugar, which means that it will undergo the Maillard reaction (i.e. browning) when used in baking. In most ways it behaves exactly like sugar in baking and cooking; absorbing and retaining moisture, melting and setting at the same temperatures, and soluble in water at 20c. It is also a prebiotic.


Tagatose has an identical mouth-feel to table sugar – it is produced in the the same granular crystal form. It is around 90% as sweet as table sugar, so shouldn’t need enhancing with high-intensity sweeteners.

I’ve had tagatose, and for my money, it tastes perfect. And I mean, motherflipping PERFECT. It tastes exactly like sugar. Unfortunately however, some people can have EXTREMELY bad reactions to tagatose. Everything I’ve been able to glean from casual conversation on forums and comment threads suggests that some people have no problem with it, while others experience the most godawful of side effects… and I am one of those people.

After doing my due diligence researching tagatose, I finally managed to order some (links available below), and was super-excited when it arrived. I tore open the packet and immediately brewed a cup of tea and added a couple of teaspoons (around 10 grams) – and ohmygod it was so good… I had found it. I was like Indiana Jones drinking from the carpenter’s cup. I was going to live forever.

Unfortunately, it turns out I was more like the Nazi archaeologist whose life-force drained from his body and then exploded in a shower of man-flavoured desiccated coconut, because I spent the next day and a half crawling between my bed and the bathroom as if I’d been dragged down to hell by the worst flu I’ve ever had. For me, tagatose is extremely hydrophilic, so it attracts water in my body like a sponge, and if you react badly to it like I did, you may find yourself evacuating every atom of moisture from your body over and over again… Jesus, it was terrible. Like, I’m-dying-how-come-satan-has-it-in-for-me? terrible.

Sweetener Profile

Tagatose Sugar
Sweetness Where table sugar has a sweetness of 100% 92% 100%
Glycemic Index Where glucose has a G.I. of 100 0 65
Calories per teaspoon Where a teaspoon is, on average, 4g 6 16

Benefits & Side Effects

In some individuals (and I’m definitely including myself here), tagatose can cause extreme diarrhoea in only modest quantities – which is a hige shame for me personally, because aside from this, I would consider it a perfect sugar replacement in every way.

It has no effect on blood sugar levels, a far lower caloric value than table sugar, and will brown and react just like real sugar.

But PLEASE USE EXTREME CAUTION if you want to try this out. Various guidelines suggest no more than 50g of tagatose per day. I would suggest no more than two teaspoons (8g) and see how you go!