Kitchen Myths

Facts and fiction about food and cooking, by Peter Aitken

Raw vegetables provide enzymes that promote healthy digestion

Sorry, no, never, nyet, fuggedaboudit. Raw plants do contain enzymes that are broken down by cooking, but (1) These are plant enzymes that have no function in the human body, and (2) Enzymes in raw food will be broken down by the digestive process anyway. Furthermore, those places that promote “live” enzymes are just feeding you a bunch of hogwash in order to separate you from your money. An enzyme is just a chemical (a protein, to be exact). It can no more be “live” than a tube of toothpaste.

7 responses to “Raw vegetables provide enzymes that promote healthy digestion

  1. Pauline December 31, 2011 at 8:01 pm

    I like that last line, ‘no more live, than a tube of toothpaste’. 🙂

  2. Twm Davies January 10, 2012 at 3:37 pm

    I’d be wary about saying never. While I agree that false health claims are made for ‘live’ plant enzymes which is no more than snake oil, that’s not to say that something digestively useful isn’t lurking in the canopy of a rainforest or under the ground waiting to be discovered. There are many plants that produce proteases with supermarket meat tenderising often being derived from Bromelain or Papain extracted from Pineapple and Papya fruits respectively. These plant enzymes break down meat very effectively and from what i’ve read, should work at lower PH of the stomach acid(though probably at a reduced rate). Therefore you could easily argue that consuming pineapple and meat simultaneously is a counter example as it does aid digestion!
    However, our endogenous proteases are perfectly suited to smashing up meat peptides into amino acids so there is no benefit in the example.

    Products such as Pancrelipase are life saving enzyme replacements for those with cystic fibrosis and chronic pancreatitis, and they are delivered in enteric coated preparations so that they are released into the GI tract roughly where the pancreas would deposit its enzymes. Finding plant enzymes with equal function might for instance reduce the cost of the medical preparation.
    There are other examples such as lactase replacement in lactose intolerance- etc.

    Keep up the good work, but may I just suggest that sceptical writing requires acknowledging that there’s an awful lot we don’t know or simply hasn’t been proven. For instance I couldn’t say for certain that no enzymes survive the digestion process (and i’m not really keen to spend hours isolating enzymes in human feces either!)

    Medical student

    • kitchenmyths January 10, 2012 at 7:45 pm

      Thanks for your very interesting post. But, I think my point stands. While there are, as you point out, some plant enzymes that have legitimate uses, they all seem to be for illnesses and other special situations and are used in concentrated/isolated form, not as the raw fruit/vegetable.

  3. Ellen Sauter, ND January 14, 2012 at 11:25 pm

    Enzymes naturally present in plants begin to break down the cell walls when the plant is picked, damaged or chewed (a process called digestion in the body of an animal, including humans). Cooking does destroy some of the enzymes (how much depends on the temperature of cooking) and this is why folks should eat fruits and vegetables raw or lightly steamed. Canning and processing foods at high temperature does destroy the inherent enzymes (this applies to meats and dairy products also) and requires that the body do more work than it was intended to do, simply to digest a meal. For this reason, supplemental plant enzymes are often recommended to assist in digestion.Plant enzymes are different than the body’s own enzymes and can be very helpful for many digestive complaints. All cells of the body produce enzymes to carry out cellular functions, but eating food without enzymes present and without supplementing creates an undue burden on the pancreas and other organs and cells in the body, which could instead be using their enzymes for other metabolic processes. In general, enzymes are simply active or inactive at a certain pH and temperature, and do “survive” the digestive process, simply waiting for the right conditions to be re-activated or re-cycled.
    Ellen Sauter, ND – Licensed Naturopathic Physician – Oregon and Washington

  4. paulskav February 3, 2012 at 2:53 pm

    Although I respect NDs, I call “BS” on the above. It may be true that the body has to do more “work” because some of these enzymes are destroyed, there is no evidence that the body cannot do this work as a part of its normal functioning, nor is there any evidence that prolonged eating of cooked foods presents any kind of health risk. In fact, we have the evidence that human beings have been surviving (and thriving!) on diets of cooked foods for thousands of years.
    The improved health experienced by many people who switch to raw food diets is most likely due to the overall increase of fruits and vegetables in their diet (especially if they were eating like a typical American before) as opposed to their preparation.

  5. Ann August 17, 2012 at 7:55 pm

    When I first heard of this enzyme fad I almost choked. I’m a biologist and what these people are saying makes no sense. They’re not talking about soaking steaks in orange or pineapple juice either..

  6. jjones July 3, 2013 at 4:04 pm

    Though there are some valid points made here, none of you has it quite right.As to kitchenmyths point that an enzyme is no more alive than a tube of toothpaste, that is really not accurate. Alive, however is not the correct word. Enzymes can be either in a precursor form, which is inactive(zymogen), an active form (called the Native enzyme) or in a non-functinal form (called denatured). Cooking denatures enzymes (as do a number of other things). And the temperature of cooking is not the only relevent thing, the time is also important. It is very unlikely that any enzymes survive any reasonable time in a steamer, its a quite efficient way of denaturing an enzyme. (Though there are some thermophilic bacteria which live in hot springs and are capable of surviving at near boiling temperatures. Their enzymes are stabilized by special chemical bonds). When you freeze food, it is usually necessary to blanch it in boiling water, sometimes, depending on the food, for as little as 30-60 seconds. The purpose of blancing is to denature the lytic enzymes (lytic enzymes are enzymes that break things, down, that is digest). If you don’t do this your frozen veggies don’t keep well, even in the freezer. The reason high temperature cooking is potentially unhealthy has nothing to do with enzymes but rather that there are some nasty chemical that are produced at higer temperatures.
    If consuming “live” enzymes, that is native, active enzymes, has any benefit it is that it probably does help somewhat in digestion. Probably, but maybe not all that much. If you chew your food well (who does?) than all of those lytic enzymes that Ellen points to have at least the time in your mouth to go to work. Maybe some of them will make it through your stomach in their active form but how much of them will is hard to say. Most enzymes are fairly stable at the pH of your stomach (pH3); what they don’t like is the churning of your stomach. Enzymes can and are denatured by shaking an enzyme solution in beaker for example. Again, some are more stable than others. As someone above pointed out, the pH of the stomach essentially turns off most enzymes, not completely, but nearly so. So not much use will come of those ingested enzymes whhile the food is in your stomach. Any enzymes that do make it through your stomach in their native form will go back “to work” when they reach your upper intestine where the pH is a comfy 7.4 or so. Of course once there, they are immediately under attack by the proteases released by your pancreas (which, BTW, are also suicidal and attack each other. Attack of course isn’t the right word….Enzymes don’t survive in your gut,(for too long) because digestion of proteins (and fats, sugars, starches) is what your gut is very cleverly designed to do.
    As to enzyme supplements, this can be a very different thing. Have you ever heard of a product called “Beeno”.?It is an OTC product available in any drugstore . It reduces the gas you get when you eat beans. Beans have an carbohydrate (or maybe a protein, I don’t remember) which humans lack the enzymes to digest. Beeno provides that enzyme in a pill form=. The pill is coated so that it doesn’t dissovle in your stomach and with the enzyme in dry form, not dissoved inSodigestive enzymes supplements might help some who suffer from reduced levels of enzyme production (older people for one Probabbly a waste of money for anyone else your stomach acid its protected for surface denaturation effects (i.e. the churning of your stomach. The coating dissoves in your stomacvh. I can testify that it does work. As to the argument that your pancreas doesn’t have to work so hard because of all the active enzymes you have consumed, you pancreeas just doesn’t know that. It releses however much it’s going to release no matter what you ate. And there is no other use for these enzymes in other functions, they are specific to your gut

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