Friday, January 23, 2009

Fructose Index is the new Glycemic Index

I've recently read a lot of literature from Hammer Nutrition, from whom I recently bought a bottle of electrolyte capsules. As I read, I learned they use long-chain Maltodextrin in their Hammer gels because (though a complex carbohydrate instead of a simple sugar) it has a Glycemic Index twice as high as table sugar (meaning that when eaten, it quickly and significantly spikes blood sugar.) I immediately wondered (as a former borderline diabetic back when I was fat) whether I should therefore avoid Maltodextrin. Surprisingly, researching that on their Web site led me to a PDF article on pages 1 and 3 of their Endurance News, Issue 058: "Fructose Called Most Dangerous Sugar." suggesting high fructose foods may be a far more important problem than high glycemic index foods, by increasing insulin resistance, this way:
"1) Unlike other sugars, fructose causes blood levels of uric acid to rise rapidly.
2) Uric acid in the blood reduces levels of nitric oxide (NO), especially in the endothelial lining of our 'endothelial NO'.
3) NO enhances the efficiency of insulin, increases blood flow to muscle and enhances glucose uptake.
4) Animals that lack endothelial NO develop insulin resistance and other features of metabolic syndrome: a cluster of symptoms linked to increased risk of diabetes and cardiovascular disease."

Googling the term "fructose index", in turn, led me to an article in the Whole Health Source blog. Key line: "it is the ingestion of foods that induce insulin resistance that carries the increased risk for obesity and cardiovascular disease and not eating foods that stimulate insulin secretion."

Also note this:
"Fructose, but not starch or its component sugar glucose, causes insulin resistance, elevated serum uric acid (think gout and kidney stones), poorer blood glucose control, increased triglycerides and LDL cholesterol in animal studies and controlled human trials. All of these effects relate to the liver, which clearly does not like excessive fructose (or omega-6 oils.) ... Drs. Johnson and Segal recommend limiting fructose to 15-40 grams per day, which is the equivalent of about two apples or one soda (choose the apples!). They also recommend temporarily eliminating fructose for two weeks, to allow the body to recover from the negative long-term metabolic adaptation that can persist even when intake is low."

For me, this means a bit of change, as I've been taking seriously government recommendations to eat 4-5 fruits a day. [Update: actually only recommends 2 cups of fruit a day for me.] I've limited those to actual whole fruits, rather than juices or processed items, but if this research is correct, even those aren't good in the quantities I've been feeling virtuous about eating.

The particular villain in the above articles was high-fructose corn syrup, which I already carefully avoid, but now it looks like we need to also be careful of fruits and even vegetables bred to be extra sweet. Even honey is listed as problematic. Naturally, table sugar is also a problem, even when hidden behind such labels as "cane juice."

I haven't found an official fructose index yet, but here's an informal one posted by the blog Natural High Transition (as reformatted by me for easier understanding):
"Grams fructose / 200 kcal serving
0 avocado, raw"

1 rowal, raw (?)
3 cranberries, raw
4 apricots, raw
6 nectarines, raw
7 clementines, raw
8 peaches, raw & grapefruit, raw
9 oranges, raw & tangerines, raw & pineapple, raw & raspberries, raw
11 bananas, raw & blackberries, raw & melons, cantaloupe, raw & abiyuch, raw (?)
----------- Safe Cutoff? ---------------
12 strawberries, frozen, unsweetened, raw
13 plums, raw & currants, raw
14 dates, deglet noor & kiwi & cherries, sour, red, raw
15 strawberries, raw
16 melons, honeydew, raw & persimmons, Japanese, raw
17 blueberries, raw & cherries, sweet, raw
18 figs
21 pears, raw
22 watermelon, raw
23 apples, raw & dates, medjool
24 grapes, red or green (seedless), raw
(Lower numbers are better in this list. Those in bold are often on my shopping list.)