As shown in the table above, peanuts contained between 1024-2048 HAU when raw. However, after either boiling, microwaving, or roasting, between 98-100% of the lectins were destroyed.
Are lectins bad for your health?
According to a 2018 Consumer Survey conducted by the International Food Information Council (IFIC), approximately 36% of Americans follow a specific diet [1]. According to the survey, two of these diets, the Whole30 and Paleo diets, are followed by 12% of Americans [1]. Both advocate the avoidance of legumes because they contain lectin [2]. The idea of a lectin-avoidance diet was made famous by Dr. Steven Gundry in his 2017 book, “The Plant Paradox.” Gundry argues that while plant foods are generally considered healthy, some of them contain lectins, which lie at the heart of many of today’s common health problems including inflammation, leaky gut, autoimmune diseases, obesity, and cancer [3].
As with many foods and even water, consuming large amounts of lectins could be toxic for humans [4]. However, there is no current recommended daily limit. Between 1976 and 1989, there were 50 reported cases of kidney bean food poisoning [10]. Symptoms of acute poisoning included abdominal pain, vomiting, and diarrhea. The source of the outbreak was identified as lectins in uncooked or partially cooked kidney beans. Cooking kidney beans significantly decreased the amount of lectins in them from between 80-100,000 haemagglutinin units (HAU) to <400 HAU [10]. Therefore, care should be taken to properly cook legumes like kidney beans to avoid adverse effects.
What do we still not know about lectins?
The reality is that there is still much to learn about the role that lectins play in human health. Most of the available studies that have been conducted were done in ways that make it difficult to translate the findings in a public health setting, including:
- Studies conducted in animals
- Studies conducted on isolated human cells
- Studies where lectins were isolated from the foods that contain them
Benefits of lectins: What does lectin do to the body?
We do not fully understand the actions of lectins either by themselves or within foods. Available evidence suggests that in some cases, lectins may even be protective against cancer, some viruses, and infections. For example, PNA, the main lectin in peanuts, seems to be highly reactive to tumor cells. It has been associated with suppression of tumor development in mice [8]. When used in medical applications, it also helps drugs to be more effective because they can recognize the tumor cells better with PNA than without it [8]. PNA seems to be effective at suppressing the Herpes Simplex virus, while Machaerium lectins in the sunflower plant have been shown to effectively inhibit HIV [8]. Research surrounding the structure and biological functions of lectins is still ongoing, and more needs to be done to understand the unique characteristics of various plant lectins and their application in humans.
The problem of eliminating plants
It is also crucial to consider the synergistic actions of nutrients within a whole food and their physiological responses. Most of the lectin-containing plant foods listed above have been shown to provide multiple health benefits for humans. For example, regular peanut consumption has been associated with reduced risks of heart disease, cancer, diabetes, inflammation, obesity, Alzheimer’s, and gallstone disease [13]. Therefore, the recommendation to eliminate lectin-containing plant foods runs against the larger body of scientific evidence that promotes them for better health. To eliminate plant foods from one’s diet would be to forfeit that protection they provide for the body.
Should you eat lectins?
It is not necessary to eliminate lectin-containing foods from the diet. Proper cooking methods can significantly reduce or eliminate lectins in foods, making them safe for consumption. Further, the large body of scientific evidence shows that these foods (including peanuts) are overwhelmingly associated with positive health outcomes.
