Move over gluten - 'lectin' is the new food fad in town according to Irish dietitian
Lectin has recently been touted as the new enemy - but is there any credibility behind the theory that the protein was developed to 'defend' plants from humans? Our resident dietitian Orla Walsh has the low-down
Food fear-mongering continues as a new supposed enemy called 'lectin' comes out of the shadows. Remarks suggesting that this component is how certain vegetation "defend themselves from being consumed by humans" are being made. Not the most scientific of arguments, as I doubt animals love being eaten either.
In science it is generally considered sensible to be wary of the person trying to sell you something - in this instance a book. The truth is, very few foods are perfect. Most of them have both "good" and "bad" aspects. Due to this you can nearly always make foods fit into the most current theory.
Nonetheless there's no smoke without fire so it's most certainly worth investigating. Lectins are found in many healthy foods including as seeds, tubers and legumes. They are a protein and they bind specific bits of carbohydrate. How they bind is similar to the action of velcro. The exact role of lectins in plants is unclear, although they are thought to act as a protectant from microorganisms, pests and insects.
Some articles suggest about 30pc of our food contains lectins. However, this study was looking at diets in the US in about 1980 and a lot has changed since then. Nevertheless, as lectins are found in plants, and really healthy ones like beans, peas and lentils, it goes against the grain to shun these foods, as the research in favour of eating them is plentiful.
Lectin is slightly different depending on where it's found. Assuming all lectins act in the same way may be wrong, similar to grouping all saturated fats together. Wheat germ lectin has been found to make it through the intestines, which means that it survives the digestive process, to ultimately leave our body through our stools.
As it touches on the wall of the gut throughout its journey it is being investigated for any potential harm or benefit it may cause along the way. This is especially important as lectins are known to bind to cells and may therefore be able trigger the immune system to respond. This could be a benefit in that it ups our tolerance but some worry that it may be causing a more extreme reaction leading to certain autoimmune diseases.
These questions need investigation, as currently the evidence isn't providing anything definitive.
Another area of concern is that lectins may interrupt the bacteria found in the colon. There is some suggestive evidence that the impact lectins may or may not have on the body could depend on what bacteria is residing in the individuals gut.
There is also other research to suggest that lectin activity within the gut depends on the stress that has recently occurred in the gut. Most of these studies are done in rats and we humans are different to our rodent pals. I suppose with everything dose and context seem to come into play.
It's difficult to write an article on lectins without mentioning the leaky gut syndrome debate. Leaky gut is a bit of a grey area. Some diseases like irritable bowel disease (IBS) and coeliac disease can lead to damaged gut lining, due to the nature of the condition. This compromised intestinal barrier can lead to other symptoms experienced by people including tiredness, bloating, diarrhoea and excess gas production.
Treating these conditions and diseases can help restore the gut to its former glory. Nevertheless in 1985 a study showed that lectins lead to increase gut permeability in rats. Reviews have been written to suggest that it's a chicken and egg scenario in some cases, in that the leaky gut causes these conditions rather than these conditions causing a leaky gut. There is not enough evidence in this area yet.
Research is also lacking in the area of 'leaky gut' in people without disease and if it does exist, how exactly is it fixed? There is no one answer, so be wary of anyone who answers this question with a one liner.
The lectin debate may be quickly quashed by the studies that show that normal processing of the likes of beans, peas and lentils such as soaking, cooking, fermenting and even spouting will degrade most of the lectins they contain.
For instance, it is fairly well known that red kidney beans can make people feel poorly if they are consumed raw or if improperly prepared due to their high lectin count. However when we soak them before cooking them it reduces the lectin content with estimations of about 99pc. As many of us use canned kidney beans, there doesn't appear to be any reason for concern as they have been shown to contain very low levels of lectin.
At present there is not enough research to make recommendations on lectin intake. Just because something doesn't have evidence behind it now though, doesn't mean it never will. But when it comes to your diet, it's advisable to avoid changing it without strong evidence to suggest you should.
When you consider the evidence, the research in favour of beans, peas and lentils wins out.
We know that plant-based diets are commonly consumed in the areas of the world where people live the longest. The human body is continuously adapting. We may not have adapted fully to be able to eat lots and lots of legumes without gut issues. But truth be told, when we eat a lot of anything, we usually suffer from it in some way or another.
Health & Living