Enzymes vs. hydrochloric acid

[fiamma]

So I recently got into a conversation with another vegan about the raw food diet, and he seemed pretty convinced it was all a crock, since - as he claims - any enzymes preserved by the fact of not cooking food would in any case be destroyed by the highly acidic environment of the stomach.

And I didn't know what to say... any thoughts?

[Cherry.Chops]

well id say that the acid in our stomach breaks down the enzimes alowing us to absorb it.

i dont know if this is exactly correct..but its what i think happens.
(please correct me if im wrong)

[Prawnil]

I thought this was a very great question. I was curious too, but it doesn't look as though there is a lot of information to find either way. What seems certain though, if you take Bromelain from pineapple as an example enzyme (which is one of the few that've been studied in ways relevant to this question), is that:
1. Passage through the entire digestive system (& out the other end) intact and active is possible. Also,
2. Passage into the circulation from the gut intact and active is possible.

Both only at very low concentrations (from high original doses of high concentrations), but it does mean that the common sense assumption that the acidity (and the protein-busting enzymes of the system) will necessarily destroy dietary enzymes, isn't strictly true (in every case, at least).

It's quite important, also, that the mechanism by which Bromelain (&others) can cross the gut wall whole is not understood!

After all though, that is based on a single example, and there is super-little out there right now as far as I can tell to support either view. Vulnerability to being knackered by low pH and the body's own protein breaking enzymes varies between other enzymes, but it isn't impossible for dietary enzymes to remain whole and able to act

(not all of these are based on humans
Proteinase activity and stability of natural bromelain preparations.2005
Proteolytic activity and immunogenicity of oral bromelain2004
oral bioavailability of proteolytic enzymes1996 )

[ellaminnowpea]

Hydrochloric acid is produced and pumped into our stomach to break down proteins and fats. When we eat food, our body releases HCl and enzymes, lots of enzymes. The enzymes in food aren't what break down our food, we don't get any nutrients or benefits from consuming enzymes. Our innate enzymes do the work. That said, the amount of HCl and enzymes can be affected by our food intake (this mechanism isn't completely clear though).

[Nyx]

ellaminowpea: Does this mean that we do not need the enzymes in food, this rendering the raw diet irrelevant? Or do you just mean the enymes that help digest things and not ones we need from outside sources?

Fiamma: Have you started that raw diary thread? I'm really interested to read it! P.S. I LOVE your avatar (I named my harddrive Ripley) :P

[ellaminnowpea]

I wouldn't say the raw diet is irrelevant...

But considering my studies in biochemistry, we don't need the enzymes in plants. Not that we don't need everything else - minerals, vitamins, fiber, etc. But our bodies make our own enzymes (from proteins).

[Mahk]

This, from a famous pro plant-based nutrition doctor, Dr Joel Fuhrman (although I don't think he's 100% vegan) is the best explanation of the "preserve the enzymes" misconception held by many if not most of the raw foodists I've encountered:

"Unfortunately, sloppy science prevails in the raw-food movement. Raw food advocates mistakenly conclude that since many cooked foods are not healthy for us, then all cooked foods are bad. This is not true.

The idea that stirs the most enthusiasm for this diet is the contention that cooking both destroys about fifty percent of the nutrients in food, and destroys all or most of the life promoting enzymes. It is true that when food is baked at high temperatures—and especially when it is fried or barbecued—toxic compounds are formed and most important nutrients are lost. Many vitamins are water-soluble, and a significant percent can be lost with cooking, especially overcooking. Similarly, many plant enzymes function as phytochemical nutrients in our body and are useful to maximize health. They, too, can be destroyed by overcooking. However, we cannot paint with this brush of negativity over every form of cooking.

Only small amounts of nutrients are lost with conservative cooking like making a soup, but many more nutrients are made more absorbable. These nutrients would have been lost if those vegetables had been consumed raw. When we heat, soften and moisturize the vegetables and beans we dramatically increase the potential digestibility and absorption of many beneficial and nutritious compounds. We also increase the plant proteins in the diet, especially important for those eating a plant-based diet with limited or no animal products.

...

Another fallacy promoted in the raw food movement and on the web is that the fragile heat-sensitive enzymes contained in the plants we eat catalyze chemical reactions that occur in humans and aid in digestion of the food. This is not true. Plant foods do not supply enzymes that aid in their digestion when consumed by animals. Our body supplies exactly the precise amount of enzymes needed for digestion; we are not ill equipped to digest normal food. The plant enzymes are broken down into simpler molecules by our own powerful digestive juices and even those that are absorbed as peptide size pieces (or with some biologic function) do not function to catalyze human functions. So it is not true that eating raw food demands less enzyme production by your body. "

Source.

Fiamma, I like your Ripley avatar too. Aliens is one of my all time favorite movies:
"Get away from her you b*tch!"

[Quantum Mechanic]

Yeah, we have plenty of enzymes to digest food, and they don't come from the food but from the person. That said, a diet that is high raw can be very healthy, but not for this enzymes reason. Probably simply because things like fruits and veggies and sprouts have lots of nutrients, and so if someone has a lot of those in their diet as opposed to, say, lots of fat and salt and overcooked veggies and stuff. While I'm not on a near raw diet myself, I would definitely prefer to have a smoothie or salad every other day at least, and for cooked veggies to be only lightly cooked and not salted. (but pepper is nice!) I have noticed anecdotally that when I eat more raw that I tend to have more energy, though I don't have any evidence.