Does fructose damage your body?

With all of the confusing information circulating out there concerning how bad sugar is for our bodies and debating whether sugar itself or artificial sweeteners are worse to ingest, it can make it very hard to feel like we’re not damaging ourselves by eating anything sweet. Most people tend to enjoy having something of that flavor profile in their diet, so it can be helpful to know, if you can’t abstain all together, which ones tend to be more or less harmful. Of all the types of sugar you could consume, refined fructose is by far the most damaging. Research as shown high fructose corn syrup (HFCS) is more toxic than table sugar (sucrose). Mice fed a high-HFCS diet had nearly twice the death rate of mice fed a diet high in sucrose. Table sugar consists of two molecules, which separate in your gut: fructose and glucose. Glucose travels throughout your body and fuels your muscles and brain, making it our primary and most readily available energy source. But fructose, on the other hand, goes straight to your liver where all sorts of problems result. Your liver readily turns this fructose into liver fat, which causes a slew of metabolic problems. When we see elevations on lab results for AST and ALT liver enzyme tests, fatty liver becomes a likely suspect, especially if other values like triglycerides and cholesterol are also high.

Excess fructose shuts down the part of your brain that tells you when you’re full, making overeating likely. This is triggered by the hormone leptin. Leptin is a very powerful and influential hormone produced by your fat cells. Your fat, by way of leptin, tells your brain whether you should be hungry, eat and make more fat, whether you should reproduce, or (partly by controlling insulin) whether to engage in maintenance and repair. In short, leptin is the way that your fat stores speak to your brain to let your brain know how much energy is available and, very importantly, what to do with it. You become leptin-resistant by the same general mechanism that you become insulin-resistant – by continuous overexposure to high levels of the hormone. If you eat a diet that is high in sugar (particularly fructose), as the sugar gets metabolized in your fat cells, the fat releases surges in leptin. Over time, if your body is exposed to too much leptin, it will become resistant, just as your body can become resistant to insulin. The resulting insulin resistance is at the core of a long list of serious health problems, including cancer, Alzheimer’s, and heart disease. And the list seems to grow longer by the day. Research published in The Journal of the American Medical Association (JAMA)3 shows your risk of dying from heart disease nearly triples if 25 percent or more of your daily calories come from sugar. 

You may not realize that insulin resistance affects each organ differently. For example, insulin resistance may be the first step toward the development of hyperlipidemia and cardiovascular disease. Added sugars, especially fructose, may play more of a role than salt in high blood pressure. When certain organs experience insulin resistance, specific diseases may develop. Type 2 diabetes results from the muscles not being able to properly uptake glucose, and if it starts affecting the nerves, that’s when peripheral neuropathies set it. We already mentioned its effect on the liver, which is non-alcoholic fatty liver disease. If it develops in the ovaries there is polycystic ovary syndrome, and insulin resistance by brain cells can lead to brain fog and ultimately Alzheimer’s disease.

Therefore, we need to limit the fructose-containing foods in our diets in order to minimize our risk. The majority should come from natural sources only, such as fruits, which are typically higher in fructose but also have numerous vitamins, antioxidants, phytochemicals and fiber to help offset the negative effects. Agave syrup has been touted as a better alternative to some sweeteners, but it is very high in fructose content as a result of the processing techniques. Honey is a little better but only in raw form as, once again, processing increases the concentration of fructose. Pure maple syrup in small amounts can be used occasionally and stevia tends to currently be the best option as a sugar replacement. Enjoying healthy sweet foods should be able to be part of a balanced diet, but if you find that you need to get your “sweet fix” more frequently or it leads to making bad food choices, start by eliminating the poor sources of fructose from your diet and have yourself checked for insulin resistance.

In Health, 

Dr. Brad Niewierowski