Fructose and Glucose and Monosaccharides, Oh My!
In my earlier post about fructose intolerance, I explain that fructose is a monosaccharide, or a simple sugar. Individuals with fructose intolerance struggle to digest foods that contain this sugar. Fructose is found in fruits but also a number of vegetables and sweeteners, like honey. Many people with fructose intolerance also struggle to digest fructans.
Glucose is another simple sugar found in many fruits and sweeteners. Unlike fructose, glucose is relatively easy to digest, even for individuals with fructose intolerance. Sucrose, also known as table sugar, is 50% fructose and 50% glucose.
The scientific nuances of this are a bit beyond me, but the general idea is that, when consumed at the same time, glucose can support with the absorption of fructose at a ratio of 1:1. That is, if the food you eat has at least as much glucose as it does fructose, it’s much easier for your body to digest. Any fructose that exceeds the glucose content is called free fructose. For individuals with fructose intolerance, that free fructose sits around in your gut and ferments, leading to all of the fun symptoms mentioned in the FI blog post.
With fructose-to-glucose ratios in mind, individuals with FI might actually to be able to tolerate some fruits and vegetables that contain small or medium amounts of fructose—if they contain equally high or higher amounts of glucose. Even if the ratio is good, however, foods with extremely high amounts of fructose likely won’t be tolerated even with the glucose present. Here is where the trial and error comes in (again).
Foods with 1:1 Fructose-to-Glucose or Better AND Lower Fructose Content (Probably Safe in Reasonable Serving Sizes):
Broccoli - 1:1
Carrots - 1:1
Cucumber - 1:1
Eggplant - 1:1
Grapefruit - 1:1
Green Beans - 1:1
Lemons & Limes - 1:1
Mandarins - 1:2
Mushrooms - 1:1
Okra - 1:1
Papaya - 0.3:1
Peach (fresh) - 1:1
Pineapple (fresh) - 1:1
Plum (fresh) - 2:3
Potato - 1:1 (with really minimal fructose in the first place)
Pumpkin - 1:2
Raspberries - 1:1
Spinach - 1:1 (with really minimal fructose in the first place)
Strawberries - 1:1
Sweet Potato ~ 1:1
Tomato - 1:1 (varies by type of tomato, though)
Turnip - 1:1
Zucchini - 1:1
Note: Some of the above foods, while safer in terms of fructose, are relatively high in fructans and may not be tolerated well in large servings (examples: broccoli, tomatoes, zucchini).
Foods with 1:1 Fructose-to-Glucose Ratio or Better but Higher Fructose Content (Trial & Error + Limit Serving Size):
Bananas - 3:4
Blackberries - 1:1
Cherries (sweet) - 3:4
Cranberries (fresh) - 1:1
Grapes - 1:1
Foods with Excess Fructose (Likely Need to Avoid):
Apples and apple juice - 3:1
Applesauce - 2:1
Artichoke - 2:1
Blueberries - 3:2
Canned cranberries (21g fructose/100g)
Honey ~ 4:3 (and the fructose amount is so high that it’s even more problematic)
Jams and jellies
Mango - 3:1
Most dried fruit
Most juice
Oranges - 3:2
Sweets, foods, or drinks with high-fructose corn syrup
Watermelon - 2:1
Sweetener Info
Safer for FI: aspartame, acesulfame K, saccharin, cyclamate, stevia, thaumatin
Likely problematic: sorbitol, xylitol (found in many diet or “sugar free” products)
References
