'Anti-nutrients' in your food. Should you be concerned?

Updated: Mar 30, 2020

We have so many choices when it comes to what form we buy our food in and how we choose to prepare it and cook. What was once a simple choice now becomes a process of sorting through if soaked, activated, flavoured, coated, blanched or raw is best for your health

The truth is, preparation of foods through soaking, sprouting, cooked or raw, can change the nutritional profile of the food, but how much will this impact you and your health?

Here is what some of the science says to help you understand the effect some food preparation techniques have on your food.

Birds eye view of jar of fermented purple cabbage

Soaking and sprouting: Reducing anti-nutrients

Tannins are a type of polyphenol that naturally presents in our diets. Tannins can be seen as ‘anti-nutrients’ as they have the ability to interact with proteins that can make them unavailable for us to absorb. However, when tannin-containing foods such as legumes and pulses are soaked, sprouted or pressure-cooked, their tannin content is reduced. This may be an important consideration for those who rely on plant based food sources for protein and nutrients (1, 2).

Phytic acid is another type of ‘anti-nutrient’ that can bind to nutrients like zinc, calcium, iron and proteins, which makes them unavailable for us to absorb. When grains such as millet are sprouted the phytic acid content is significantly reduced, making is better for us to use the nutrients.

Generally speaking, iron and zinc from vegetarian diets are less available for us to absorb than from non-vegetarian diets. However this could be for two reasons 1) reduced meat intake (reduced levels of nutrients) 2) or higher intake of phytates. However, in Western countries we have a varied diet from which we get our nutrients from therefore it is not clear that vegetarians or vegans will necessarily experience nutritional deficiencies (4, 5, 6)

Check out this recipe for DIY sprouting mung beans.

Cooking: Makes some foods safe and changes the nutritional profile

There is a popular study circulating, which suggests that kidney beans are harmful to our digestive system and gut lining. However, this statement is based off a study that fed 300mg of raw kidney beans to rats that weighed 80-100mg rats high doses in just 6 hours. It did find there was reversible damage to the gut lining BUT consider huge amount of beans fed compared to their weight, the fact they are raw. I’m very sure if someone fed me three times my body weight in food in 6 hours my gut would be in chaos too!

There are also some studies suggesting kidney beans are also unsafe for humans. This is because they contain a type of lectin called haemagglutinins, which can cause food poisoning like symptoms when eaten raw. Interestingly when cooked these beans are completely harmless, palatable, and highly nutritious from humans (7, 8).

Fermentation: Changes nutrient content and is a source of bacteria

In tempeh, a fermented soybean product, and in idli, a rice-legume based fermented food of India and Sri Lanka, fermentation increases the contents four B-vitamins. B vitamins, B2 and B3 are increased in many Bacillus-fermented Asian fermented foods (9).

Eating the bacteria found in fermented foods could beneficially influence your gut cells, immune system, and-gut hormone cells in a way similar to probiotic supplement strains. Recent studies using strains of food-associated bacteria such as Lactobacillus plantarum and Lactobacillus rhamnosus can directly alter receptors and inflammation in the gut (10, 11, 12).

Check out these delicious fermented recipes

Take home message

Every food will be impacted in some way depending on how it is prepared and there is not necessarily ‘right’ or ‘best’ way for your food to be eaten. My advice is to include a variety of ways you like to prepare or cook your food gain the different health benefits and taste profile each food will contain when prepared in a different way.