Fructose and Alzheimer’s disease?

We are critically examining the claims of the article, Astaxanthin: A Rising Star in Alzheimer’s Prevention. The last few articles in this series dealt with astaxanthin itself, but today we have reached the point where the Astaxanthin article begins to talk about risk factors for Alzheimer’s disease.

The first thing mentioned is fructose.

Now, as a scientist, I take immediate offense at the impassioned diatribe against this simple sugar found naturally in fruits. HOWEVER, we are dealing once again with oversimplification leading to imprecision.

It is entirely possible that you will already know what I am about to say. (I hope that is the case.) But the fructose controversy is alive and well in all types of media, so it is worth trying to shed a little light on what is really not so complex an issue.

1. What is fructose?

Fructose is a simple sugar found in fruits, berries, and some vegetables. It has the same chemical formula as glucose, the simple sugar preferred by brain neurons. That is, a molecule of either sugar contains six carbon atoms, six oxygen atoms and twelve hydrogen atoms.glucose-fructose


The difference between fructose and glucose lies in the arrangement of the atoms.

2. Does the difference in shape matter?

Well, yes, actually it does. If you read my earlier series of articles on drug discovery in Alzheimer’s, you may recall that 3-D shape is critical to protein function. Since it is the job of some proteins to make the energy from foods we eat available to our cells, it follows that the 3-D shape of the molecules in our food might also be important.

In the case of fructose and glucose, the difference in shape causes them to follow two different metabolic pathways. Glucose is dismantled very effectively by the metabolic machinery of cells and produces abundant energy in a form cells can easily use. Fructose is also metabolized, but it follows a different pathway than glucose does (because of its different shape) and becomes a free fatty acid instead of being converted easily to energy for the cell.

Your body can, and does, deal effectively with the fatty acids formed from fructose… up to a point. That point seems to be the amount of fatty acid formed from 25g of fructose per day. And therein lies the problem.

3. So what is the problem?

The problem is that many of us consume much more than 25g per day of fructose. And don’t blame the apple you ate at lunch. It is virtually impossible to exceed 25g per day of fructose if fresh fruits and vegetables are your only source. The culprit is the processed food we eat.

4. Have you heard of High Fructose Corn Syrup?

Of course you have! This highly concentrated natural sweetener is found in all kinds of processed food–not just cakes, pies and bread, but pizza dough, ketchup, mustard, soup, and more. It is almost impossible to find a food that hasn’t been sweetened by some company or other, these days. We have a natural, instinctive liking for sweet foods–and the food industry takes advantage of that by adding sweeteners to all sorts of things. Read the labels! Even things that should be healthy for you–dried fruit… simple, right?–may have been treated. I just read this on a container of trail mix: “dried sweetened cranberries.”

If you only ate 25g per day of fructose, but it came from high fructose corn syrup, would that be a problem? Probably not, though I know some would argue with me on that.

5. So foods sweetened with sugar are better for me, right?

I cannot bring myself to say that they are. Here’s the deal:

Table sugar, cane sugar, pure cane sugar… the chemical name for all of these is sucrose. sucroseSucrose is a disaccharide. That is, it is made of two simple sugar molecules hooked together. (di- means two, -saccharide means sugar) Each molecule of sucrose is made from one molecule of glucose hooked to one molecule of fructose.  If you look at the diagram at right and compare it to the one above, you will see this. So what we call sugar is half glucose and half fructose, and most of us eat much more than we should of that combination. The sweetener in my trail mix was sugar. So how much sugar did it take to sweeten those dried cranberries?  Well, the total sugars in 1/4 cup of trail mix was 7g. So if I eat a handful of trail mix four times in a day, and have NO OTHER SOURCE OF SUGAR IN MY DIET, I’m good.  But what about the bread I made my lunch sandwich with? What about the cereal I ate for breakfast? What about the dressing on my dinner salad?  You get the point.

Sugars are everywhere, they can contribute to obesity and to type 2 diabetes, and, in excess, will harm your body and your brain.

6. Isn’t fructose natural?

Of course it is. So is sugar. So is vitamin D. So is alcohol. Being natural does not mean something is good for you. There are no rules about what may be labeled natural. Natural is just a word the food industry uses to make you feel good about the processed foods you eat.

Why we love the word natural is beyond me. Spider venom is natural. Hurricanes and tsunamis and tornadoes are natural. All the poisonous plants in the world are natural. So when something is labeled “All Natural,” look a little closer at the label. Sometimes the product will actually be a healthy choice, other times not. You have to read the fine print.

7. Is there anything good to eat?

Yes. The best advice if you really want to eat healthy is to eat real food–fruits and vegetables you buy fresh (and organic, if you can afford it) and meats that are hormone free.  The most succinct advice I’ve seen on the subject was in a little book I browsed in my chiropractor’s waiting room. It said simply, “If your grandmother [or great-grandmother] wouldn’t recognize it as food, don’t eat it.” I have not forgotten the advice, though I don’t know who to thank for it. (If you know who the author was, please let me know so I can give proper credit!)

8. What about supplements?

I am not against them, with these caveats:

Remember that more is NOT always better (Too much of a good thing can be toxic.) Be sure to buy from a reputable vendor. Look carefully at the sources from which supplements are derived. Read the fine print.

I recommend reading this good, simple article on fructose and Alzheimer’s. It’s short and (dare I say it?) sweet. Enjoy.

Next time more on the presumed sources of Alzheimer’s disease.

See you then. –Susan


2 thoughts on “Fructose and Alzheimer’s disease?

  1. Great analogies, great info. I’m passing your posts to my father as he struggles to care for my mom. Tomorrow, I’ll be heading down to visit her even though five minutes after I leave, she won’t even remember that I was there.This disease is like a python.


  2. What can I say? My own mom died of cancer, after a mercifully short battle. My dad died of heart failure, but the number of notes we found reminding him of a multitude of simple things convinced me that he was dealing with the early stages of Alzheimer’s as well. He had my phone number written down on pieces of paper… in every room of his house. The disease is, indeed, like a python. My heart goes out to you and to your dad.


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