There is one problem with the Paleo diet for oh, about 30-50% of Europeans and maybe 15-20% of Americans – the low starch approach that encourages eating more fruit and sweet potatoes exacerbates many digestive, mood, and skin problems.
You hear about it often. “I’ve made all these positive dietary changes and suddenly I’m more sensitive to everything.” After years of wondering about the same thing, I may have slowly stumbled upon one, of maybe many, possible reasons for this.
What Is Fructose Malabsorption?
According to Wikipedia “Fructose malabsorption, formerly named “dietary fructose intolerance,” is a digestive disorder in which absorption of fructose is impaired by deficient fructose carriers in the small intestine’s enterocytes.”
This means that our ability to break down fructose is impaired and so fructose molecules travel down to the colon undigested. When anything makes its way down to the large intestine without first being broken down, the situation can get pretty ugly.
Many people with fructose malabsorption experience digestive troubles such as diarrhea or constipation, rashes, melancholy or anger, among others. I myself started to see a connection to fruit and my skin as well as my mood and digestion. This led me to some pretty strict elimination diets. If only I had known years ago that there were just some specific foods I needed to avoid…
Discovery Through Experimentation
I’ve mentioned countless times on this blog that, while going Paleo initially helped with many of my symptoms, it wasn’t the cure all that I had hoped for. Even after going Paleo I was still so bloated I looked five months pregnant, I still had skin issues, and I was still depressed, among other symptoms.
Going Paleo did offer so many positive benefits that I had never seen before with any other diet modification, I was well convinced that some version of it was right for me, but those few remaining symptoms were quite a blight on my self image and physical comfort.
I am stubborn and so I experimented and experimented trying to figure it out.
Finally, about 3 years into being Paleo, I narrowed my diet down to almost nothing but raw fish, raw meat, fresh juices from celery, wheatgrass, carrot, and spinach, plus white rice. That was the extent of my diet for a good two years and it was absolutely amazing.
But I guess I was just too thrilled with feeling good; I wasn’t careful about making sure my diet was perfectly wholesome. I quit making broth, never ate saturated fats, was probably missing some B-vitamins, and I may have taken a little too much to drinking in my newfound youth (blush, kinda feel stupid about that). Whatever the reason exactly, I developed a raging allergy to rice (and several vegetables which I didn’t find out about until years later) and had to quit my miracle diet. ;(
After playing around again with your usual Paleo diet and never feeling so awesome again, I went super low carb. That worked too by god! No fatigue, no depression, no acne, no nuthin. I felt great. But my extremely low carb approach came with its own set of complications. It was hard to eat enough meat and fat. I wasn’t eating veggies because, like so many others, I thought I was allergic to everything.
Until one day, about 7 or 8 months ago, someone popped round the blog and dropped a gem of advice in the comments. Maybe you should look into fructose malabsorption. It made sense. I had figured out on my own years ago that fruit does me much harm. Maybe I needed to avoid it like I avoid gluten.
Now the success with these two vastly different diets makes perfect sense.
I eliminated Fructose.
While I had thought I was reacting to everything I put in my body, I had only been reacting to fructose.
Symptoms of fructose malabsorption vary from person to person. Many of the symptoms are IBS- like symptoms and, in fact, fructose malabsorption may be one of the leading causes of irritable bowel syndrome.
- Itching and rashes
- Depression and low serum tryptophan concentrations
- Carbohydrate cravings
- Colic in babies
The test for fructose malabsorption is a simple hydrogen breath test – the same test used for lactose intolerance.
The poor man’s way to test for fructose malabsorption is by eliminating fructose and observing symptoms. This method works just as well since there are so many symptoms associated with the condition. If relief of all of these happens, you’ve figured it out.
Fructose Can Cause Depression
Surprisingly, the undigested fructose molecules in the intestine does a whole lot more damage to the body than just some annoying bloating, gas, and rashes. I mean, as if that weren’t enough, researchers have found that those free floating fructose molecules actually react chemically with tryptophan – the precursor to serotonin, one of the neurotransmitters that helps us feel happy – degrading it and lowering serum levels. Without tryptophan we feel depressed and irritable and weepy.
Researchers from the University of Innsbruck in Austria found a high correlation to depression and women with fructose malabsorption, although the same was not found in men. Another Spanish study found that 71% of the depressed adolescents they studied had sugar intolerance, compared with 15% of controls. A huge margin like this should not be overlooked.
Lactose and fructose malabsorption disorders combined were found to result in an even greater instance of depression.
Depression is more common in women with FM
We can thank Emily Deans, an MD with interests in evolutionary psychiatry, for clarifying the cause of the connection between women with fructose malabsorption and depression. Why not men she asked? The answer is because men have more tryptophan than do women.
“The researchers postulated that estrogen made the big difference. Estrogen activates an enzyme called hepatic tryptophan 2,3 dioxygenase that shifts the metabolism of tryptophan from making serotonin (happy) to making kynurenic (not happy). Women already have lower serum levels of tryptophan than men do (which may be part of the reason why we are more vulnerable to depression in the first place), so screwing up whatever available tryptophan in the diet with fructose may lead to even lower levels, and thus depression.”
Looks like if you’re a woman and you’re depressed, you had better get yourself tested for fructose malabsorption.
Safe Foods List
Not all fruits and sweeteners are created equally. Some of them have more fructose than others, and so some of them are safer than others.
Foods which should be eaten in moderation only:
- Ripe banana
- Oranges and grapefruit
- Maple syrup in small doses – doesn’t work for everyone
- Table sugar in small doses
- Distilled liquor
Foods which can be eaten liberally:
- Milk – if lactose malabsorption is not also an issue
- Leafy green vegetables
- Lemons and limes
- Yams but NOT sweet potatoes
- Tapioca – same as yuca or casava
- Corn Tortillas
Foods to Avoid List
Foods containing fructose:
- Fruit juice
- Dried fruit
- Fruit concentrates
- Whole corn
- Tomato paste
- Corn syrup and high fructose corn syrup
- Wine – dry wines might be ok in moderation
Not only do fructose malabsorbers need to avoid fructose but we need to avoid something called fructans too. Fructans are long chain fructose molecules and they usually do the same damage as fructose. The amount of fructans vary in the following foods so add after eliminating all fructose and fructan containing foods, try adding some of these back one at a time and in small amounts to observe tolerance. Many of these such as coconut, onions, and wheat are quite high in fructans and usually don’t work for any of us FMs.
Foods containing fructans:
- Coconut milk and meat
- Jerusalem artichoke
- Green beans
- Carrots – tolerance varies
- Chicory root
For a searchable database of foods containing fructose check out the website The Farting Pear.
Tips for Avoiding Fructose
The last and very important thing to know about fructose is that table sugar (sucrose) contains 50% fructose and 50% glucose. This sounds scary at first but interestingly glucose helps carry fructose through the intestines. So, when you eat table sugar the glucose part essentially holds the hand of the fructose part and helps it along. They are absorbed together so that the fructose doesn’t have to make the terrible trip down to the colon where it doesn’t belong. Now, if you eat a whole heck of a lot of sucrose, some of the fructose will probably escape down to the colon, unaided by the glucose, so don’t go overboard.
This little fact about glucose can be very useful when accidentally (or intentionally) eating something which contains a small amount of fructose. We can simultaneously eat some glucose (I use NOW brand dextrose) to avoid the ill effects of fructose. But remember, this only works in small amounts. If you decide to eat a whole entire mango, for example, adding glucose isn’t going to help you absorb that amount of fructose.
Solving a Life Long Problem
My daughter Evelyn had also been bloated quite often since she started eating solids. I never knew why. I almost figured she inherited my own bad microbial environment which I had developed after years of bad diet and anti-biotics. Turns out neither of us are in such a bad place after all. We just were fermenting fructose like crazy. (I had tried, very religiously, candida diets and anti-microbial herbs and probiotics to no avail.)
Finding out what had been causing my remaining persistent symptoms which the Paleo diet couldn’t cure was wonderful – it’s a miracle to not be stumped anymore. But to find out what is causing your own child’s discomfort is a relief beyond any other.
Evelyn has fructose malabsorption too. After all these years we finally got to the bottom of it. We have our lists printed out and hanging on the fridge. We give them to her friends, her dad, and school. She knows most of the foods herself but she likes having the list handy too.
Here is a picture of her one evening when she was bloated and very sad because she was constipated, juxtaposed with her new flat bellied self. Depression was never one of her symptoms… yet. I’m sure if she had hit puberty before finding out about this, that would have hit her too, just like it has hit all of the women in my family. Hmm, food for thought.