Monday, May 19, 2008

Real Food VII: Lentils

Lentils are a healthy food that comes with a few caveats. They have more protein and less carbohydrate than any other legume besides soybeans and peanuts, and they contain a remarkable array of vitamins and minerals, particularly B vitamins. One cup delivers 90% of your RDA of folate, so between lentils and liver there's no need for those sketchy prenatal vitamins.

Lentils must be properly prepared to be digestible and nutritious!
I can't emphasize this enough. We did not evolve eating legumes, so we have to take certain steps to be able to digest them adequately. As with all beans and grains, proper soaking is essential to neutralize their naturally occurring toxins and anti-nutrients. Anti-nutrients are substances that interfere with the absorption of nutrients. Soaking activates enzymes in the seeds themselves that degrade these substances. It also cuts down substantially on cooking time and reduces flatulence.

Phytic acid is an anti-nutrient that's abundant in beans, grains and nuts. It can dramatically
reduce the absorption of important minerals such as iron, calcium, magnesium and zinc, leading to deficiencies over time. It may be one of the main reasons human stature decreased after the adoption of agriculture, and it probably continues to contribute to short stature and health problems around the world.

Lentils and other seeds also contain trypsin inhibitors.
Trypsin is one of the digestive system's main protein-digesting enzymes, and seeds probably inhibit it as a defense against predators. Another class of toxins are the lectins. Certain lectins are able to bind to and damage the digestive tract, and even pass into the circulation and possibly wreak havoc. This is a short list of a few of the toxins found in beans and grains. Fortunately, all of these toxins can be reduced or eliminated by proper soaking. I like to soak all legumes for a full 24 hours, adding warm water halfway through. This increases the activity of the toxin-degrading enzymes.

Here's a method for preparing lentils that I've found to be effective. You will actually save time by doing it this way rather than cooking them without soaking, because they cook so much more quickly:
  1. 24 hours before cooking, place dry lentils in a large bowl and cover with 2" of water or more.
  2. After 12 hours or so, drain and cover the lentils with very warm water (not hot tap water).
  3. Drain and rinse before cooking.
  4. To cook, simply cover the soaked lentils with fresh water and boil until tender. I like to add a 2-inch piece of the seaweed kombu to increase mineral content and digestibility.

many thanks to *clarity* for the CC photo


JCMDesign said...

This post reminds me - I've been wondering about sprouted grains. Does the sprouting process break down lectin and other toxins and make the grain a more viable source of nutrition?

Stephan said...

Hi jcmdesign,

Yes, sprouting breaks down the lectins. You just want them barely sprouted, because if they sprout too much they will begin producing lectins again.

Ed said...

Stephan, do you still think it is proper to drain and rinse before cooking? I ask because I think I read in one of your later posts on soaking rice that the fermentation process breaks down the phytic acid and the bound minerals that are released then precipitate (or something) in the solution, so that suggests you'd actually want to keep that soaking water. Any updated thoughts here?

I love lentils, they are easy to prepare and they are tasty.

Stephan Guyenet said...

Hi Ed,

I do think it's best to drain and rinse. The tannins and other anti-nutrients leach into the soaking liquid and remain there.

villaneweva said...

Hi Stephan, I enjoy your blog immensely. After soaking for 24 hours, how long do you have to cook to remove all the lectins and other harmful substances?


Stephan said...

Hi Villanewva,

I think it's fine if you just cook them to taste.

benn686 said...

Are legumes good too, assuming you soak them overnight to remove the lectin?

I'd like to do a legumes/lentil soup on a slow cooker!

Neil said...

Have you studied how effective your process is? What were your results? What were you controls and limits of lectin detection?

Boryana said...

What about B-vits? After soaking, rinsing and cooking, do any of the water-soluble vitamins remain?

Anders said...

Is it the same with canned beans or are they considered "safe" from lectins?

Deller Trask said...
This comment has been removed by the author.
mark cool said...

I'm confused about the distinction between "very warm water" and "not hot tap water". Are you saying hotter than hot tap water?

whisperingsage said...

Stephan, you said in an earlier post that if the lentils sprout too much, they will make lectins again. How will this affect my attempts at growing lentil greens for my rabbits and goats? I am attempting soil mineral baalanced pasture and hope to free range my animals on it (not exactly the rabbits- they are in a wire lined pen and I must cut their forage and put it in there.). I tried to put raw dry lentils in the rabbit feeder but they dug them out and don't seem impressed. I am trying for an alternative to rice bran which in itself has been a wonderful supplement, but now is contaminated with arsenic. I decided on camelina seed and lentils, and am trying to grow them as greens.

Philip Torrance said...

Lentils ... have more protein and less carbohydrate
than any other legume besides soybeans and peanuts?
I was looking for high-protein low-fat legumes
with also the best protein-completeness
and the best were black beans and kidney beans .
. lentils were too low to even make the list;
but what you will like about them,
is that being so low in protein and fat
makes them one of the least-toxic legumes .

tkwonster said...

So once the lentils are soaked properly, would it then be safe to eat them raw if I desired? I would like to know if it's something I can add to green smoothies.

jewiuqas said...

Very interesting. To tell the truth, I abandoned eating lentils when I had learned about phytic acid. I was not sure how to properly prepare them. From what is said in this post I would say that lentils need exactly the same treatment as beans. Which means that the seeds contain high enough quantities of phytase to hydrolyze PA. Stephan, it would reassure us, if you could cite your sources as to this point. Another important question is the critical temperature at which lentil phytase gets destroyed. With beans it is around 65°C (sorry, I am not very familiar with Fahrenheits). When soaking them (beans), I keep water temperature under 60°C, to be on the safe side (too low is no good either, for the process slows down). Will that be okay if I do exactly the same with lentils? By the way, are lentils legumes? They aren’t grains, that much is sure, or nuts. My experience with beans is that dephytinization makes them extremely tough (in fact their toughness is a proof, that PA is completely gone, there is some chemistry behind, but don’t ask me what). After the 60°C bath for 24 hours, I did not succeed in cooking them soft in 24 hours! The only solution was a pressure cooker. Even with it, it takes about 90 minutes at top pressure. But the result is really worth the trouble, it gives a chilly con carne like heaven. I am looking forward to preparing some delicious lentil dishes soon. All this said, I fully agree with you, Stephan, that our ancestors did not make such a fuss about preparing their beans, lentils etc. Just soaking overnight in pure, soft rainwater may have done the thing for them. Anyway, if you are coping with some health issues, such as caries for example, taking extra steps might be justified. And, for that matter, where do you get pure rainwater nowadays?

Brady Shackelford said...

Is the nutritional content of dried legumes less than the nutritional content of fresh legumes? And would that nutritional content return to normal once the legume is reconstituted? I ask because the 5-HTP content in fresh Griffonia, an African legume, is 20% but only 6% in dried. I would assume that the 5-HTP content would return to 20% once the legume is reconstituted and that this same idea would apply to all legumes.

Philip Torrance said...

I've seen dried lentils sprout after being soaked;
so, I would say they still have what they need to survive,
but their dry-adapting process
might convert any 5-HTP to something else.
. the best way to get tryptophan in the brain
is to eat some low-protein moderately glycemic meal
-- white rice with mct oil before bed knocks me out.

Kelly_Phillipson said...

Hi Stephan,
The Westin A Price blog says to add ACV when soaking the beans. It also says that in order to eliminate the phytic acid one has to germinate for a few days. I was wondering what your thoughts are on that.

Unknown said...

You should not use hot tap water for consumption, always use cold water that has been heated in a kettle or pot. Hot tap water draws unhealthy minerals from the pipes.

Ian said...

@ Mark Cool:

Re: "I'm confused about the distinction between "very warm water" and "not hot tap water". Are you saying hotter than hot tap water?"

The article is claiming that the warmth is to encourage the activity of enzymes. Hot tap water is usually 50 Celsius or above - hot enough to destroy enzymes. You want it warm 30-40 Celsius for enzymes to work best.