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Is Fructose Bad for Your Brain?


Fructose often gets a bad rap, and for good reason. Americans increased consumption of high-fructose corn syrup by 1,000% between 1970 and 1990 as the sweetener became the go-to syrup for soda and other sugary drinks. Fructose is also added to plenty of sweetened packaged foods and is the natural sugar found in fruit. It's also the main sugar in agave.

A new study from UCLA suggests that genes in the brain can be damaged by fructose, which may impact memory and learning and could even cause Alzheimer's disease, diabetes, and heart disease.

The research was done with rats split up into three groups. The first group drank plain water, the second group had fructose water (with an amount of fructose equal to a person drinking 34 ounces of soda), and the third group was given fructose water and DHA, a type of omega-3 fatty acid found in oily fish such as salmon and trout. The rats were trained to escape a maze and were tested again after six weeks on their new regimens.

How did the rats do? The fructose rats took twice as long as the other groups to escape the maze, while the DHA and fructose rats did just as well as the rats given just water. This led the researchers to conclude that fructose was slowing the rats down. On the bright side, DHA could help offset the negative effects of fructose. The genes in the rats brains changed as a result of the fructose, with those changes being linked to Parkinson's disease, depression, and other brain diseases.

Should you go for the giant Slurpee with a side of salmon? Not so fast! Keep in mind, the study was done on rats, not humans. Any volunteers want to get some friends together to repeat the rat experiment and see what happens? Didn't think so.

Here's what we know about the effects of fructose in people: Overdoing it on fructose is linked to a higher risk of high blood pressure, heart disease, and type 2 diabetes. Fructose may also be more fattening than other types of sugar, based on how it's metabolized.

So should you cut down on fruit or quit juicing for good? Whole fruit provides phytochemicals, fiber, vitamins, and minerals that prevent chronic diseases. Plus, the fiber slows down the metabolism of fructose in fruit, unlike sugary drinks or candy. Having a couple of servings of fruit a day whole or in a smoothie will work wonders for your health. But juicing large amounts of fruit and removing all the fiber? You're left with mostly fructose. The same goes for store-bought juice—choose whole fruit first. And when you do have juice, make sure it's 100 percent juice.

The bottom line: Limit all the added sugars you're eating, not just fructose. Eating too much sugar, whether it's raw cane sugar or white sugar, is linked to inflammation, which increases chronic disease risk. Getting excess sweet stuff also raises triglyceride levels, upping your heart disease risk.

Need to satisfy your sweet tooth? Try fruit-based desserts like my Mango Froyo or Vegan Chocolate-Covered Strawberries.


Christy Brissette, RD

Christy Brissette is one of North America’s top dietitians and a leading nutrition and food communications expert. She is the President of 80 Twenty Nutrition, a nutrition and food media company and private practice. Her mission? To end food confusion and dieting once and for all.  More →

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