~~ I do not have medical experience, just sharing some of my research. ~~

I recently watched some YouTube videos [23,24,25,26]  that labelled fructose as a poison and a chronic toxin.
I proceeded to validate the science behind this, and found that the independent research may not use as strong a word as poison, but agrees that fructose is definitely unhealthy when consumed in excess,
and can result in metabolic syndrome? conditions.

~~~~~~~~~~~~~~~~~~~~~

Which-ose?

Glucose is the main type of sugar in the blood and is the major source of energy for the body's cells. Glucose comes from the foods we eat or the body can make it from other substances. Our bodies and brains need glucose!

Fructose is a sweet substance which occurs naturally in fruits and vegetables. It is often used to make food sweeteners, such as high fructose corn syrup (HFCS).

Sucrose is made of 50% glucose and 50% fructose. It is found naturally in fruits and vegetables, and is purified from sugar cane and sugar beets for use in cooking and food production.

Fructose Facts

  • Fructose does not stimulate insulin, and with no insulin there is NO release of leptin (which inhibits hunger). Fructose also does NOT suppress the hunger hormone ghrelin, as would normally occur with food intake. The only possible result when eating fructose is that you'll be hungry and want to eat more!
  • Fructose metabolism is completely different than for glucose.
    • 80% of glucose is consumed by the body's cells for energy, leaving only 20% to be metabolized by the liver.
    • Our body's cells do not know how to process fructose, so it is almost entirely metabolized in the liver. The by-products are fat deposits, VLDL, and uric acid. So the bottom line, fructose is a carb that is metabolized as fat!

For diabetics dealing with low blood sugars, it is important to select foods high in glucose as opposed to fructose. You can buy glucose tablets at the drugstore that work really well. 

Fructose is the sweetest of the common sugars.
It is found naturally in fruits, fruit juices, honey and root vegetables, as well as in processed sweeteners and sucrose.

Because fructose is metabolized as fat, the glycemic index of fructose (how much it increases blood sugar) is only 19 compared with pure glucose which has a GI of 100. However, fructose has a much higher glycemic load?.

HFCS (high fructose corn syrup) was introduced in the 1970s, and is a liquid sweetener made from the sugar in corn. Specifically, corn starch is a chain of glucose molecules, and when broken down it becomes corn syrup. Enzymes are then added to convert some of this glucose into fructose.  HFCS and sucrose (table sugar) both consist of 1 glucose and 1 fructose molecule, and are metabolized in exactly the same way. HFCS is cheaper than sugar, with better flavor enhancement and longer shelf life. It’s more stable and consistent, especially in acidic foods and drinks.

Fructose is only harmful in large amounts, such as a diet with excessive added sugars. It turns out that there is not enough fructose in whole fruit to cause concern [4]. Fruit has a low calorie density and lots of fiber, and is very hard to overeat since the fiber makes you feel full. Fiber also slows the absorption of carbs which makes it easier for your liver to metabolize. However, when fructose hits your liver fast and in large amounts, as is the case when you drink soda or fruit juice, it gets overwhelmed and can trigger adverse health effects over time.

When the liver metabolizes fructose, one of the end products is triglyceride, a form of fat. Uric acid and free radicals are also formed. Excess consumption of fructose in the form of added sugars may cause:

  • Increased levels of VLDL (very-low-density lipoprotein) and triglycerides, which can lead to fat accumulation in the liver and damaged liver function. When released into the blood stream, triglycerides can potentially lead to fat accumulation around other organs and the growth of fat-filled plaque inside artery walls, as well as health issues such as arteriosclerosis (thickening of the artery walls), pancreatitis (inflammation of the pancreas), non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH)? and an increased risk of heart disease and stroke. [1,2,3,4,5,6,7,8,9,10,11,12]
  • Increased levels of uric acid in the blood, which can turn off production of nitric oxide (a substance that helps protect artery walls from damage), and can also lead to gout (a painful type of arthritis), increased joint pain, acne, heart disease, kidney disease and high blood pressure. [1,2,4,6,8,9]
  • Insulin resistance, which can lead to obesity, type II diabetes and heart disease. [1,2,3,4,6,7,8,9,10,11,12]
  • Overeating and resulting weight gain. Since fructose does not trigger the release of insulin or leptin (the satiety hormone), it therefore doesn’t suppress appetite like glucose does. [4,8,10]
  • Leptin resistance, which can disturb body fat regulation and contribute to obesity. [2,4,6,8,11]
  • Lipid imbalance in the blood (too much LDL and too little HDL), which can lead to atherosclerosis – a buildup of plaque in the arteries. [3,4,6,8]
  • Gut problems, including leaky gut, bloating, IBS, diarrhea and constipation. [21,22]
  • Overactive fructose metabolism in the brain, which may trigger Alzheimer's disease. [16,17]
  • Inflammation within the endothelial cells that line your blood vessels, which is a risk factor for heart disease. [14,15]

And now for some good news.
Currently there is research being done to develop a ketohexokinase (KHK) inhibitor. KHK is the primary fructose metabolizing enzyme, and inhibiting this enzyme could potentially block fructose metabolism. [20]

The Obesity Epidemic

According to the WHO, worldwide obesity has nearly tripled between 1975 and 2021.
Before the mass production of refined sugar, humans rarely consumed it in high amounts.

The 1980 and 1985 dietary guidelines recommended the reduced intake of all fats. In response to this mandate, the food industry replaced the fat calories in processed foods with simple carbohydrates, including sucrose and HFCS.

But this didn't help, and the obesity rate still continues to increase.
And now we know that a high sugar diet is a high fat diet!

So what can we do?

  • First and most important, avoid all sugary drinks including sodas and fruit juices!! Drink water or green tea instead. Add berries, lemon or lime if you want more flavor.
  • Reduce the amount of processed foods that you consume. Processed foods often contain HFCS when you least expect it, such as in protein bars, yogurt, BBQ sauce, condiments, salad dressing, frozen foods, bread and crackers, apple sauce, canned soups & fruit, and baby formula! [12,13,14]
  • Eat more servings of fresh vegetables and fruits, along with plenty of fiber. Snack on whole foods like nuts and fruits instead of cookies and candy.
  • Read ingredient labels. If you see HFCS or added sucrose, look for alternative products.
  • Reduce alcohol consumption. Except for the 10% of ethanol that is metabolized in the brain, the remaining ethanol is processed by the body in exactly the same way as fructose.
  • Limit consumption of agave. Diabetics may benefit from agave's low glycemic index (17), but may not realize that it is 90% fructose! That is a much higher fructose content than table sugar (50%) or HFCS (55%).
  • Drink more water, which may stimulate your metabolism! [18,19]

Conclusion

While experts agree that excessive fructose is unhealthy, its health effects remain controversial.
However, it does seem to be in our best interest to limit the amount of fructose in our diets while the scientists keep busy gathering more empirical evidence 😉.

Back to Top

1. Harvard health: Is fructose bad for you?
2. NIH: Fructose and Sugar - a major mediator of NFLD
3. NIH: The role of fructose in NASH
4. Healthline: Is fructose bad for you?
5. NIH: How high fructose intake may trigger fatty liver disease
6. NIH: Fructose and metabolic diseases
7. Healthline: Evidence shows some sugars are worse than others
8. MedicineNet: How is fructose bad for you?
9. WebMD: What to know about HFCS
10. MedicalNewsToday: Is fructose bad for you?
11. NIH: Fructose, insulin resistance, and metabolic dyslipidemia
12. Healthline: 12 common foods with HFCS
13. EatThis: 23 surprising foods with HFCS
14. Healthline: 6 foods that cause inflammation
15. ScienceDirect: Fructose-induced inflammation
16. GeneticEngineeringNews: Fructose metabolism in brain may help initiate Alzheimer's disease
17. Frontiers: Cerebral fructose metabolism as a potential mechanism driving Alzheimer’s
18. University of Colorado: Water may be an effective treatment for metabolic syndrome
19. John Hopkins University: Drinking more water may help you lose weight
20. NIH: Pharmacologic inhibition of KHK may prevent fructose-induced metabolic dysfunction
21. StudyFinds: Too much fructose may cause a leaky gut
22. IntegrativePractioner: Excess fructose consumption may cause leaky gut

YouTube videos:

23. Dr. Richard Johnson, Nov 2020 - Fructose: The key culprit for obesity & metabolic syndrome?
24. Dr. Eric Berg, Nov 2017 - Fructose: The Most Dangerous Sugar
25. Dr. Robert Lustig, Jul 2009 - Sugar: The Bitter Truth
26. Dr. Robert Lustig, Oct 2013 - Fat Chance: Fructose 2.0
27. Dr. Brad Stanfield, Feb 2021 - Fructose Research 2021

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