A study published last summer in Cancer Research shows that fructose is even more of a nutritional villain than previously suspected. More than any other kind of sugar, it appears to trigger cancer cells to divide and proliferate.
Researchers at the University of California–Los Angeles extracted pancreatic tumor cells from patients and grew the cells in petri dishes. They added glucose (another simple sugar long known to fuel the growth of cancer cells) to one dish and fructose to the other. The cancer cells used both glucose and fructose as fuel, but the fructose also activated the cellular pathway that drives cell division while triggering cellular activities that helped cancer cells rapidly metabolize both fructose and glucose.
The main source of fructose in the North American diet is high-fructose corn syrup and other refined sweeteners, such as sucrose, dextrose and maltose. U.S. consumption of high-fructose corn syrup alone shot up 1,000 percent between 1970 and 1990.
Today, the average American eats 70 grams of fructose per day — a number triple the recommended daily limit.
The best way to limit fructose intake is to greatly reduce or eliminate processed foods and sweetened beverages from your diet. But you can further limit your total fructose intake by choosing fruits — like berries and stone fruits — that have lower fructose concentrations, and going easy on fruit juices and dried fruits, which deliver a lot of fructose per serving. Osteopathic physician and New York Times best-selling author Joseph Mercola, MD, suggests no more than 20 grams of fructose per day, with no more than 15 grams coming from fruit.
The Fructose in Fruit
Fruits are good sources of nutrients and fiber, but some contain a significant payload of fructose, too. Here’s a low-to-high listing of some commonly eaten fruits (grams of fructose in bold):
- Peaches — 1 cup, 154 g — 2.36 g
- Clementines — 2 fruits, 148 g — 2.42 g
- Raspberries — 1 cup, 123 g — 2.89 g
- Pineapples — 1 cup, 165 g — 3.50 g
- Grapefruit — 1 cup, 230 g — 4.07 g
- Bananas — 1 cup, 150 g — 7.28 g
- Apples — 1 cup, 125 g — 7.37 g
- Mangoes — 1 cup, 165 g — 7.72 g
- Pears — 1 fruit, 148 g — 9.22 g