To reduce antinutrients, such as certain lectins (irritate gut lining, possible cause of auto immune disease) and phytic acid, (affect mineral absorption, inhibit digestive enzymes), legumes generally need to be SOAKED before cooking them at a high temperature.   The lectin phytohemagglutenin (PHA) (causes blood cells to clump) is the presumed toxic lectin inherent in many bean species, and is particularly concentrated in red kidney beans. Raw, unsoaked red and white kidney (cannellini) beans fed to rats at 20% and 40% of diets killed them in a few days. Noah ND, 1980

In addition to soaking, you can also choose to sprout or ferment legumes.  These extra steps make legumes even more digestible and nutritious.

Sprouting is generally followed by cooking.   However, “raw foodists” prefer not to cook them, since they want to preserve enzyme activity destroyed by boiling.

Fermenting requires that the beans are cooked either before or after fermentation.  Fermenting them after cooking, avoids a bad smell that emanates from uncooked fermenting beans and reduces cooking times. Fermented soybeans are called “natto”.  Although sprouting and fermenting beans does reduce lectin activity, the most effective method to use after soaking is boiling at a HIGH temperature, preferably with a pressure cooker, which is almost as effective at reducing dietary lectins as avoiding them.

FIRST – Soak Legumes / Beans – To remove phytate

Soaking beans for 18 hours reduces phytic acid in beans by up to 70%, depending on type of bean;

• Soak legumes/beans in water for 7-24 hours to remove phytates.    Use a bowl 3-4 times the volume of the dried beans to allow for swelling; completely cover beans with water; change water frequently to get rid of phytic acid that leached into the water.
• Some beans do better soaking in an acidic medium.   Depending on type of bean, add suggested amount of apple cider vinegar, whey, kefir, plain yogurt or lemon juice.

* SMALLER BEANS NEED A LONGER SOAKING TIME

• Rinse beans after soaking.   Using a sieve makes it easier to rinse off the bubbly scum on top of the beans (btw, these gassy bubbles are what some people experience after consuming unsoaked beans – need I say more? 🙂 )

NOTE: Soaking deactivates some lectins, but high heat boiling does a superlative job.    E.g. In PHA-inactivation tests, soaking red kidney beans for several hours deactivated about 75% of its hemagglutinins (53,000hau/g dry weight of sample to 18 hau/g, white kidney beans didn’t change much (17hau/g to 14 hau/g), and broad beans, with low amounts (3 hau/g), didn’t change at all; Noah ND, 1980

SECOND – After soaking legumes your antinutrient-reducing choices are:

Choice 1. Sprout (“Germinate”) legumes BEFORE cooking them

 (However, “raw-foodists” prefer not to cook them after sprouting)

Benefits of Sprouting beans

• Reduces lectins, tannins, phytates;
• Increases vitamins / protein – depending on the bean
• Reduces carbohydrate
• Makes beans (also grains, nuts, seeds) easier to digest  – by breaking down complex sugars and starches in the beans and unlocking digestive enzymes; this also favors beneficial gut flora;
• Reduces gas;
• Decreases aflatoxin – a carcinogen naturally present in some seeds E.g. peanuts, corn, almonds and other nuts
• Slightly milder taste than unsprouted legumes.

Effectiveness of sprouting at reducing antinutrients

• Reduces phytate – ~30-80% depending on bean, sprouting increases phytase enzyme activity to break down phytic acid.
• Slightly decreases lectins and protease inhibitors, Ref.

How to sprout legumes

WARNING:  sprouting lentils increases lectin activity

• Drain rinsed beans after soaking and place in a sprouter out of direct sunlight.
• Repeat rinsing and draining – every 8-12 hours.
• Beans should sprout in a few days – depends on bean type
• High heat cook sprouted legumes.  Sprouted legumes will cook a bit faster than unsprouted ones

Choice 2:  Ferment legumes BEFORE or AFTER high heat cooking

Benefits of traditionally fermenting beans

• Traditional fermentation allows beneficial bacteria to eat lectins.
•  Fermented legumes contain probiotic bacteria.
• Reduces phytates.   Increases phytase enzyme activity, which breaks down phytic acid; 2011 study showed a several fold increase depending on grain.   Marshall Arebojie Azeke et al, 2011

NOTE: Eden brand fermented beans use traditional fermentation methods after washing, soaking and cooking the beans prior to being fermented.

How to ferment beans

Not yet available

Third – Cook legumes at HIGH heat

Cook AFTER spouting / BEFORE or AFTER fermenting

Benefits of cooking Legumes / Beans.    Cooking kills bacteria and breaks down difficult-to-digest starches

Effectiveness at reducing antinutrients.  E.g. Cooking red kidney beans at high temperature reduces PHA lectins by 99% – although even small amounts have an inflammatory effect.

• Raw = 20,000 to 70,000 hau (hemagglutinating unit)
• Fully cooked at high temperature = 200 to 400 hau

How to cook legumes

• In fresh water, boil beans for at least 15 minutes using HIGH heat.   Using a pressure cooker reduces lectins even more, reduces cooking time to ~8 mins.

WARNING:   Beans cooked in too low a temperature (e.g.in a slow cooker) can actually increase lectin activity

Note on canned beans: canned beans are almost lectin-free because the canning process uses sufficient heat to reduce lectins to insignificant amounts; however, beans used in canning typically have not been soaked long enough to remove phytic acid before being cooked; One exception, according to their website, EDEN canned beans are soaked, the soaking water discarded,  and then the soaked beans steam-blanched and rinsed before being pressure-cooked for a specified amount of time depending upon the bean variety. 

Cooked beans can be frozen for later use