Dear Dr. Mo: I love sweet foods. I am slightly overweight but nothing serious and I try to control it. I’ve heard that fructose can cause heart disease and is bad for the health. Now I know fructose is found in fruit so how can this be true?
Dear reader: Let me begin by saying that two predominant sugars in our modern diet are glucose and fructose. Our cells need sugars (carbohydrates) to extract energy form them. Virtually every cell in our body can use glucose to get that energy.
With fructose however, the story has a little evil twist – only the liver cells can get energy directly from fructose metabolism and this is where the trouble starts for us.
Fructose in liver undergoes a series of metabolic changes and one of those changes is that the liver uses fructose to create fat!
So when you think of fructose think of fat as well.Feed your liver with enough fructose (especially in today’s fast diets which unfortunately abound with sugary foods and beverages) and gradually, very small droplets of fat will begin to accumulate inside the liver cells – such a process of fat build up is called non-alcoholic fatty liver disease, virtually unknown before 1980 and affecting a large number of adults and 80-90% of those who are obese or have diabetes.This goes to say that what’s changed in the past few decades has not been us physically, but our life styles and especially our diets and I don’t mean extra fruit intake but all the sweet foods and drinks we manufacture.
There’s some good news though, at least initially. Early on in the process, the fat accumulation in the liver is reversible and requires some dietary and life style changes.
After some time, the liver may become inflamed and suffer a low-grade damage. If nothing is done to stop the process, the inflammation may become more severe leading up to liver cirrhosis – an aggregation of scar tissue induced by damage and subsequent fatal loss of liver function.
This is similar to what happens to livers of people who drink too much alcohol over longer periods of time.
Metabolizing fructose through the liver has other very harmful effects:
- Increase of blood pressure
- Increase of LDL (so-called “bad”) cholesterol
- Elevation of triglycerides in the bloodstream
- Promotion of the buildup of fat around organs (visceral fat)
- Tissues may become insulin resistant initiating diabetes
- Other changes that are harmful to the arteries and heart
Two relatively recent studies have established a strong link between higher intake of fructose with higher chances of developing or dying from heart disease.
So to answer your question, yes, fructose does indeed affect our health in a negative way but only if taken in excess amounts and over long periods of time. Avoiding these damaging effects of course doesn’t mean giving up fruit, which is good for you.We’ve been eating fruit for thousands of years and our bodies are adapted to the amounts of fructose that we get from them.
Instead, it is another excellent reason for avoiding the refined sugars and high-fructose corn syrup used to make breakfast cereals, pastries, soda and fruit drinks, and other sweet foods.
Usually all that’s required are a few changes in our lifestyles and diet habits to avoid many of the health problems down the road. Your question today was a good place to start this change.
Yours in health