Cooking Legumes

highest total anti-oxidant content
721 lentils
648 chickpeas
622 small red beans
602 black kidney beans


Toxic Factors in Edible Legumes and Their Elimination

The American Journal of Clinical Nutrition
, Volume 11, Issue 4, 1 October 1962, Pages 281–298, 

Perhaps the best known of the antinutritional factors found in legumes is the trypsin inhibitor which is widely distributed in nature. Despite the considerable amount of research has been conducted on this substance, especially in soy beans, the exact mechanism whereby it inhibits the growth of experimental animals is still not clearly understood. The most recent evidence would seem to implicate pancreatic hypertrophy as one of the main physiologic responses to the trypsin inhibitor.

Many legumes also contain substances which agglutinate red blood cells. That they may have nutritional significance is indicated by the fact that purified preparations of these plant hemagglutinins inhibit growth when incorporated into the diets of rats. Their mode of action, however, remains obscure.
Other toxic components reported to be present in a wide variety of legumes include goiterogenic factors, cyanogenetic glucosides, saponins and alkaloids.
Lathyrism and favism are diseases in man which are associated with the consumption of the specific legumes, Lathyrus sativus and Vicia faba, respectively. Although toxic principles have been isolated from several species of lathyrus which can produce neurotoxic symptoms in animals, the exact etiology of this disease in man is not known. No toxic principle (capable of producing a disease resembling favism in animals) has yet been isolated from Vicia faba.
Most of the antinutritional or toxic effects of legumes can be partially or wholly eliminated by proper methods of cooking. This accounts for the fact that heating serves to enhance the nutritive value of many legumes. Since the protein of most leguminous seeds is deficient in methionine, supplementation with this amino acid frequently effects a marked improvement in the biological value of the protein. It is still not clear, however, to what extent the effectiveness of methionine and other dietary supplements might also be due to their ability to counteract the nutritional stress imposed by these toxic components.


Not all lectins are toxic
very toxic: ricin from castor oil seed.
toxic : kidney beans
non toxic: tomatoes lentils, peas, chickpeas, faba beans, and other common foods.

eating raw kidney beans leads to acute gastroenteritis presumably via a lectin hemagglutinin effect.

legumes have other toxins like saponins which are presumably also destroyed by boiling.


Destroying lectin in red kidney beans via cooking:
Thompson LU, Rea RL, Jenkins DJA. Effect of Heat Processing on Hemagglutinin Activity in Red Kidney Beans. Journal of Food Science, Volume 48, Issue 1 January 1983, Pages 235–236.

1. presoaked beans : 
cook for 15 minutes @ 100C....however, require 1 hour @ 100C to consider soft enough to be edible.

2. dry beans :  
pressure cook for 45 minutes at 15psi.....but require 60 mins to be soft enough to be edible.

3. canned beans equivalent to : 
pressure cooked for 30mins (?presoaked?)

Evidence for longevity correlation with legume consumption.
Darmadi-Blackberry I, Wahlqvist ML, Kouris-Blazos A, Steen B, Lukito W, Horie Y, Horie K. Legumes: the most important dietary predictor of survival in older people of different ethnicities. Asia Pac J Clin Nutr. 2004;13(2):217-20.
Australia, Sweden, Indonesia, Japan

Reduced risk of colorectal cancer
Zhu B, Sun Y, Qi L, Zhong R, Miao X. Dietary legume consumption reduces risk of colorectal cancer: evidence from a meta-analysis of cohort studies. Sci Rep. 2015 Mar 5;5:8797.

Singhal P, Kaushik G, Mathur P. Antidiabetic potential of commonly consumed legumes: a review. Crit Rev Food Sci Nutr. 2014;54(5):655-72.

Metabolic Syndrome risk factors reduced in overweight and obese.
Mollard RC, Luhovyy BL, Panahi S, Nunez M, Hanley A, Anderson GH. Regular consumption of pulses for 8 weeks reduces metabolic syndrome risk factors in overweight and obese adults. Br J Nutr. 2012 Aug;108 Suppl 1:S111-22.

Reduce Met Syndrome and Inflammation
Hermsdorff HH, Zulet MÁ, Abete I, Martínez JA. A legume-based hypocaloric diet reduces proinflammatory status and improves metabolic features in overweight/obese subjects. Eur J Nutr. 2011 Feb;50(1):61-9.
4 serves a week drops CRP 40%

All cause mortality reduces with increase plant foods (including legumes)
Schwingshackl L, Schwedhelm C, Hoffmann G, Lampousi AM, Knüppel S, Iqbal K, Bechthold A, Schlesinger S, Boeing H. Food groups and risk of all-cause mortality: a systematic review and meta-analysis of prospective studies. Am J Clin Nutr. 2017 Jun;105(6):1462-1473.


All References for Greger's video