Which is worse: Glucose or fructose?

David posted the following interesting question on the Nutrition Diva Facebook page:

“Your podcast on nutritional trade-offs made me think of the following question: I try very hard to limit my intake of sugar. But some foods do need some kind of sweetener, and so I’m wondering about what alternatives to table sugar you recommend. Some are higher in glucose, and that brings with it a higher glycemic index. Others have a lower glycemic index, but are higher in fructose, which experts say to avoid. What do you think?”

Most sweeteners, including table sugar, honey, maple syrup, agave nectar and so on, contain glucose and fructose in varying amounts. Table sugar is half glucose and half fructose. Agave nectar on the other hand is about 70% fructose and only 30% glucose.

These two sugars are metabolized through different pathways. Glucose is absorbed into the blood stream and fructose is metabolized in the liver. So agave nectar is going to cause a lower rise in blood sugar than table sugar. On the other hand, studies in rats suggest that too much fructose can increase the amount of fat stored in the liver and that’s not good.

So are you better off with a sweetener that’s higher in glucose or one that’s higher in fructose?

Here’s the thing: Both the effects of glucose on blood sugar and the effect of fructose on liver function are highly dose dependent. When you’re only consuming a small amount of added sugars, you’re unlikely to get into trouble on either front. So, as long as you’re keeping your consumption of added sugars to the suggested levels—5 to 10% of calories–it doesn’t really matter that much which sweetener you choose.

But many people consume large amounts of sugar. So which is the better choice for those who eat a lot of sugar?

titanic-deck-chairsIf your diet is high in sugar, this becomes a matter of choosing the lesser of evils. In that case, it would probably depend on that person’s situation. A person with diabetes or pre-diabetes would probably want to prioritize limiting the effect on blood sugar and go with a sweetener that’s lower in glucose. A person with NAFLD (non-alcoholic fatty liver disease) would probably want to avoid overburdening the liver and go with a sweetener that’s lower in fructose.

But obviously there is a third option. In either scenario, you’d be far better served by reducing your sugar intake–at which point your dilemma largely disappears.

7 thoughts on “Which is worse: Glucose or fructose?

  1. Really good answer. Thanks.

    Any suggestions on HOW I can reduce sugar in fluids?

    I know wine has sugar and isn’t good for the liver, but it’s become a habit that I need to replace with something. Juices are high in sugar and calories, too, even ones like V8 juice.

    I’ve been trying to drink just water or mint tea, but sometimes that just doesn’t cut it, especially at cocktail hour.

    1. One of my favorite mocktails is club soda with a splash of cranberry or pomegranate (just enough to turn it the color of a cosmo) and a squeeze of lime. Just a bit of added sugar from the juice. Another is club soda with a healthy dash of Angostura bitters.

  2. I read something the other day that I found to be quite disturbing. It said that when a person limits how much carbohydrates one eats, that all that does is make one’s body derive its energy from the protein and fats that one eats. It said that whatever pounds one loses by following such a diet, is largely water. Basically, then, all one is doing by limiting how many carbohydrates one eats, is a self-induced bodily dehydration. I find this disturbing, because as a severely overweight person, the only diet plan which I have had any success in at all, has been to limit my overall non-fiber carbohydrates intake to about 180 grams per day. I had thought that limiting my carbs was forcing my body to use some of my excess bodily fat. But if this is not the case, and if what that book said is correct, then I feel as if I have no hope at all of ever losing my excess weight.

    1. Raymond, it’s true that limiting carbohydrates will cause your body to use other nutrients (fats and proteins) for fuel. It’s also true that much (but not all) of the initial weight loss associated with the initiation of a low-carbohydrate diet is actually water. However, if you continue to take in fewer calories than you burn, you will lose more than just water. If limiting your non-fiber carbohydrates has been a successful weight loss strategy, then I would encourage you to continue with that.

      1. Thank you for answering me. I think I understand what you are saying. Basically, that while there is no way around the reality that one can lose weight only by eating fewer calories (or burning more off with increased exercise) that at least one benefit of eating a low-carbs diet, is that it naturally makes a person eat less. The reason for this, is that it is carbs above all else that causes fatties like me to be so addicted to food. I even heard that sugar is more addicting than heroin! So by eating fewer carbs, I am basically taking all the fun out of eating, making me eat less. I realize that sounds kind of depressing, but it looks like that is the bottom line truth of things. btw, another factor worth mentioning that I neglected to say about myself above, is that I am not only about 140 pounds overweight, but am also pre-diabetic, with diabetes running in my family. And so another benefit of limiting my total carbs, is that perhaps it lessens my chances of developing full-blown diabetes, as my blood sugar is kept at a moderate level. Of course, complicating all this, is that even if I eat a low-carbs diet, just the fact that I am so overweight, makes me a prime candidate for diabetes. And from what I understand, diabetes is not only the leading cause of blindness, but is even strongly correlated with dementia. So terrifying! Maybe what I need to do is to put a big piece of very thick black masking tape over my mouth, and refuse to eat until I lose all of my excess weight.

  3. Thanks for the mocktail suggestions.

    Raymond, I believe Monica can help clarify this a bit further, but “Carbs” has taken on a meaning of being bread, pasta, etc. It is my understanding that there are carbs in fruits and vegetables, as well, so by limiting a certain TYPE of carb like processed wheat, you are not eliminating all carbs. The thought of diabetes is frightening. When I was first diagnosed, I turned to the diabetes asso for lots of information. Just a thought.

    Monica, sugar is my biggest concern. I can’t seem to find out how much sugar is in a 5 oz glass of Trader Joe’s pinot to count in my 25g of allotted added sugar.
    it’s not sweet but not dry either.
    Also, bananas are quite sweet. Should I be including them in the sugar count?

  4. Do you know what I think? That the more I stick to eating nothing but high omega 3 fish such as sardines and herring, salad vegetables (that is, vegetables that can be eaten raw), and healthy oils (such as extra virgin olive oil), that the healthier I will be, the less I will have to worry about ever getting diabetes or dementia, with my excess weight falling almost effortlessly off of me. Of course, circumstances do not always permit one to stick to such a diet, plus there is the danger of it becoming too monotonous. My answer to that, though, is to try as much to stick to such a diet, compromising it only when outer circumstances call for it. And of course, I suspect that every once in a while just enjoying oneself by eating anything one wants, also has its place, just as long as one really only does that on rare occasions, like maybe once per month.

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