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Fructose and lectins: Health disruptors or not?

July 1, 2020
Karen Davis, BSDH, RDH, sifts through the research regarding fructose and lectins in the human diet. Just how healthy are they?

Your food choices today will matter tomorrow.

I took note of the foods and beverages my husband was served on the “liquid diet” when he was recently hospitalized for testing. David is a cancer survivor and transplant recipient. He was given Ensure with 31 grams of sugar, apple juice with 24 grams of sugar, and lemon ice with 15 grams of sugar. Even though I’m not good at math, I know that totals 70 grams of sugar from one meal alone. The American Heart Association established recommendations in 2009 for Americans to limit daily intake of added sugar to 26 grams for women and 38 grams for men.1 The next day, I took note of his meal, which was full of lectins (carbohydrate-binding proteins), such as bread, beans, tomatoes, and potatoes. Are fructose and lectins disrupters of our health or not? If they are, why would hospitals serve them to patients with chronic diseases?

Questions such as these have been tumbling around in my mind for years because I have a daughter and a husband who both live with chronic illnesses. You and I treat patients who must live with chronic diseases daily. Food studies are expensive, and study design variations can make comparisons of data impossible. It is no surprise that there are conflicting data from which to draw conclusions. 

Here are my bottom-line conclusions from years of researching how foods with fructose and lectins impact the body:

Table sugar (sucrose) is half fructose and half glucose. Our bodies need glucose, but there is no biological need for fructose. It is pro-inflammatory by raising triglycerides and blood pressure, increasing liver fat, and increasing the risk for insulin resistance, type 2 diabetes, and obesity—just to name a few health implications evidenced in thousands of studies. Overindulgence of sugary foods can be addicting. Fructose also interferes with the natural production of the hormone leptin, which helps regulate the feeling of fullness, hence making overindulgence easy. I inform my patients to avoid fructose for these reasons. 

Most foods that have lectins—such as lentils, citrus fruits, berries, bell peppers, and tomatoes—are actually good for us because of their antioxidant, vitamin, fiber, and mineral value, with exceptions for certain populations. Patients with celiac disease should not eat gluten, a lectin found in wheat, rye, and barley, since gluten triggers an immune response in the small intestine that can lead to serious complications. Some individuals have gluten sensitivities, which can contribute to bloating, discomfort, joint pain, and fatigue. Patients with autoimmune diseases, such as irritable bowel diseases and arthritis, may find that avoiding lectin-rich foods improves their symptoms. For the majority of people, however, I believe there is compelling evidence that whole-food, plant-dominant diets (even those with lectins) are anti-inflammatory and beneficial. 

Our food and beverage choices fall into two categories: disease-promoting and disease-preventing. Foods really aren’t neutral. Certain foods function as antioxidants, providing nutrients and promoting cellular repair, while other foods are pro-inflammatory, increasing oxidative stress, which promotes cellular damage. If we could see the cellular damage of pro-inflammatory foods before our eyes, likely no one would choose to eat them, regardless of how they taste.

If you are reading this and thinking, “What about the evidence?” you might want to consider three books and one evidence-based website that have been helpful resources for me.

The first is a book written by Robert H. Lustig, MD.2 Dr. Lustig is a pediatric endocrinologist at the University of California and one of the world’s top researchers. He has been researching and lecturing about what fructose does to the body for years because he has witnessed it unfolding before his eyes in his treatment of unhealthy children. The book is titled, Fat Chance: Beating the Odds Against Sugar, Processed Food, Obesity, and Disease. It has 22 chapters, each citing evidence-based research for his conclusions. Here are two beginning statements from chapter 11 in the book. “Sugar is a toxin. Plain and simple.” And, “Fructose isn’t the only cause of obesity, but it is the primary cause of chronic metabolic disease, which kills . . . slowly.”

A second resource is a book written by Michael Greger, MD, FACLM, titled, How Not to Die: Discover the Foods Scientifically Proven to Prevent and Reverse Disease.3 His book has 15 chapters unveiling how certain ingredients in foods (including fructose) are pro-inflammatory and other food choices (whole-food, plant-based diets) are anti-inflammatory. Dr. Greger also does an exhaustive citation of studies to back up his conclusions related to disease prevention and disease promotion of various foods. He is also the founder of nutritionfacts.org, which catalogs evidence-based videos related to health, wellness, and nutrition. He has published an informative video debunking claims from some authors who suggest lectins are ruining our health and are the source of weight gain.4

A third resource related to lectins is the book by Steven R. Gundry, MD, titled, The Plant Paradox: The Hidden Dangers in ‘Healthy’ Foods that Cause Disease and Weight Gain.5 Dr. Gundry attempts to make the case that lectins in general promote disease (and therefore he adopts a lectin-free diet) and purchasing his lectin-blocking supplements will help restore health. Some of his conclusions sound convincing, but after a thorough study of the citations referenced and literature published, I have a differing opinion.

I believe that while a diet avoiding lectins may help or even be necessary for a small part of the population, most individuals benefit greatly from plant-based foods, irrespective of lectins. Should you wish to explore limited, but emerging evidence surrounding lectins and autoimmune diseases, a valuable resource is an article titled, “Lectins, Agglutinins, and Their Roles in Autoimmune Reactivities,”6available online at Google Scholar. 

Is fructose a health disruptor? My personal conclusion is that mounds of evidence support that it is. Avoid fructose to live a longer and healthier life. What about lectins? Are they health disruptors? I am unconvinced that they are for the general population. Many of these plant-based lectins are anti-inflammatory, which helps repair cellular damage. Remember, foods and beverages are not neutral. Your choices today will matter tomorrow.  


  1. Johnson RK, Appel LJ, Brands M, et al. Dietary sugars intake and cardiovascular health: a scientific statement from the American Heart Association. Circulation. 2009;120(11):1011-1020. doi:10.1161/CIRCULATIONAHA.109.192627
  2. Lustig RH. Fat Chance: Beating the Odds Against Sugar, Processed Food, Obesity, and Disease. New York, NY: Penguin Random House; 2012.
  3. Greger M. How Not to Die: Discover the Foods Scientifically Proven to Prevent and Reverse Disease. New York, NY: Flatiron Books; 2015.
  4. Greger M. Dr. Gundry’s The Plant Paradox Is Wrong. NutritionFacts. September 13, 2017. Accessed February 28, 2020. https://nutritionfacts.org/video/dr-gundrys-the-plant-paradox-is-wrong/
  5. Gundry SR. The Plant Paradox: The Hidden Dangers in ‘Healthy’ Foods that Cause Disease and Weight Gain. New York, NY: Harper Collins Publishers; 2017.
  6. Vojdani A. Lectins, agglutinins, and their roles in autoimmune reactivities. Altern Ther Health Med. 2015;21(suppl 1):46-51. 
Karen Davis, BSDH, RDH, is the founder of Cutting Edge Concepts, an international continuing education company. She practices dental hygiene in Dallas, Texas. Davis is an independent consultant to the Philips Corporation, PerioSciences, and Hu-Friedy/EMS. She can be reached at [email protected].