I need a little help...

[Hazelip]

A friend of mine, who has a few woowoo tendencies, just tried to "inform" me that vegetables lose 10% of their nutrients as soon as they are removed from the vine, or ground, or tree. I simply asked him where they went, and he shrugged. I countered by stating that the whole cooked-vegetables-are-less-nutritious-than-raw-veggies fact was, indeed, a myth, but I found myself wanting in backup rationale.

Now, I know I've come across this in the past. But, I'm sleepy, I've had a full day of work, doctor's appointment (nothing is going to fall off, thankfully), house-hunting, Valentine shopping, and Survivor/CSI (my crack). So, I don't think I was searching quite well...

Can anyone help me with a suitable reference for this?

Thanks much,
Jake

[SortingItAllOut]

Originally posted by Hazelip
A friend of mine, who has a few woowoo tendencies, just tried to "inform" me that vegetables lose 10% of their nutrients as soon as they are removed from the vine, or ground, or tree. I simply asked him where they went, and he shrugged. I countered by stating that the whole cooked-vegetables-are-less-nutritious-than-raw-veggies fact was, indeed, a myth, but I found myself wanting in backup rationale.

Now, I know I've come across this in the past. But, I'm sleepy, I've had a full day of work, doctor's appointment (nothing is going to fall off, thankfully), house-hunting, Valentine shopping, and Survivor/CSI (my crack). So, I don't think I was searching quite well...

Can anyone help me with a suitable reference for this?

Thanks much,
Jake

Hi Jake,

I've got the same addiction. Haven't watch the CSI tape yet, but I thought I was going to fall out of my La-z-boy when the guys got spanked by the girls in the immunity challenge. Haha!

Here's a link about this topic. Not sure I believe any of it, but for what it's worth: http://cbc.ca/stories/2002/04/11/Consumers/nutritionlost_020411

Take care,
Sort:)

[edthedoc]

Your friend is partly right:

Fruit and vegetables contain vitamins which are rather delicate molecules: they break down when cooked so eating raw veggies is better for you.

As far as loosing 10% when picked: so what? Are we supposed to eat them off the tree?

The problem with most of our ("western") diets is that we eat too much, particularly too much crap i.e. processed foods, sugar, salt, fat.

Eating fresh unprocessed food is much better for many reasons (let's lay off the issue of pesticide residues etc.) but true vitamin deficiency is quite difficult to achieve with the overall amount of food we eat.

I don't eat a brilliant diet but absolutely love a decent peach/melon/plum etc. but am not too keen on raw veg.

"Be not a pie nor a carrot muncher"

[Goshawk]

The "fruits and veggies lose 10% of their nutrients" isn't too far off base. Here's the fact behind the factoid.

http://www.goaskalice.columbia.edu/1432.html
Vegetables lose some vitamins just by sitting around. It could take up to two weeks from the time they've been picked until they reach your plate. By this time, 10 - 50 percent of the less stable nutrients may have disappeared. It has to do with how long ago those fruits and veggies were actually picked. By the time you buy that pear, it may be 5 months old, that apple may be 6 months old, and those carrots may be 9 months old.

http://www.itdg.org/html/technical_enquiries/docs/cold_storage_fruits_vegetables.pdf

And, as for raw fruits and veggies *automatically* being more nutritious than cooked...

http://www.aces.uiuc.edu/~nutrican/summaryfindings.html
In 1995, the University of Illinois Department of Food Science and Human Nutrition released a comparative analysis of a variety of canned, fresh and frozen fruits and vegetables that let a little-known secret out of the can – canned fruits and vegetables are as nutritious as their fresh and frozen counterparts.

< snip >

Generally speaking, if a fruit or vegetable is considered healthy and nutritious when it is fresh, it also will be nutritious in its canned form. The reason – the heating process used in packaging canned products causes only minor loss of most nutrients, similar to what is lost when fresh foods are cooked at home.

Once the product is canned, it usually maintains its nutrient levels, even after one to two years of storage. This is particularly important, since canned products are harvested at the peak of ripeness and usually canned only a few hours after they’re picked, sealing in the nutrients.

Meanwhile, "fresh" fruits and vegetables often are picked before their nutrient content has peaked and may spend as many as 7 to 14 days in transit, even before they hit the supermarket. Add to this the number of days they spend in the store – and in the crisper drawer before they’re consumed – and it’s easy to see that "fresh" can just as easily be found in the canned food aisle as in the produce department. And unlike many fresh items, canned products are available year-round at their peak quality.So, unless you're absolutely certain of how old those tasty-looking fresh whole green beans at Kroger are, you're probably better off eating frozen or canned green beans.

[rwald]

But that doesn't answer the question of raw vegetables vs. cooked vegetables. I could easily see how some vitamins are broken down by heat, or could leech into the water they are cooked in. Anyone know about those issues?

[Jeff Corey]

Home grown tomatoes vs winter supermarket tomatoes up north.
I've seen Florida tomatoes picked green to be shipped north. Is it true that they flood them with carbon dioxide or some other gas to turn the skin red?
I don't know about the nutrients, but they sure taste like guano when compared with a home grown tomatoe right off the vine.

[Goshawk]

Well, generally speaking, cooking a vegetable or fruit helps to break down the fiber a little bit, and makes it a teensy bit more digestible. The tradeoff is that you do lose a small amount of nutrients. Vitamin C is especially vulnerable to heat.

You can get around this by cooking them in as little water as possible (microwaves are great for this), and by saving the cooking water, which will have vitamins and minerals dissolved in it, and using it in soups.

http://www.kidfitconnections.com/wcpreserving%20nutrients.htm

Also, starchy vegetables like potatoes and legumes (lima beans, pinto beans, etc.) aren't really digestible in the raw state anyway. The carbohydrates have to be cooked before the human digestive tract can handle them.

So if you have normal digestion and good teeth and chew your food well, you can have a perfectly healthy diet by eating all your fruits and veggies raw. But I always thought it was easier, and tastier, to cook the green beans first. :D

[Pouli]

Originally posted by rwald
But that doesn't answer the question of raw vegetables vs. cooked vegetables. I could easily see how some vitamins are broken down by heat, or could leech into the water they are cooked in. Anyone know about those issues?

The question of nutritional value is a complex one. I every type of food differs a lot in its various "nutritional" components. Some general principles for vegetables foods are these :

Proteins: Most vegetables have very low protein content. Protein content usually decreases by 10-30% with by heat. An exception is Soya because the heat treatment destroys an anti-digestion substance it includes. I would say that for most vegetables don't worry about proteins because in any case the content is very low in the first place.

Carbohydrates: Again thermal processing reduces the overall concentration. On the other hand it breaks down the long carbohydrates to shorter forms, more easy to digest so the actual usage by the human digestive system increases. For example think what happens to boiled or fried potatoes.

Lipids: Most vegetables are low on lipids. Others are very high on lipids for example olives. Heat degenerates a percentage of its content. The most important effect of heat is the transformation of unsaturated lipids to saturated. The later are considered “bad”. Also exposure to oxygen (air) for a period of time will make the lipids rancid.

Vitamins: The concentration of all vitamins decreases the older the food is. Vitamins C and E are especially affected by oxygen so vegetables in cans or bags are protected. Heat always destroys vitamins to a degree. Boiling will reduce them by a factor of 10-50%. Also water soluble vitamins will indeed be drained to a degree by contact with water especially with boiling. Not so with lipid soluble vitamins.

Minerals: The concentration of minerals varies a lot with different vegetables. Generally they are considered more stable than the other substance. They are marginally affected by heat. Prolonged contact with water will indeed remove a percentage of them.

Still an important point to notice is that heat treatment will definitely reduce the micro organism population in all types of vegetables. This is especially important if you live in countries that often have vegetables infected by micro organisms like echinococcus, salmonella, E.coli. Heating is much preferable to raw then.

Also many vegetables have potentially dangerous and even poisonous substances that are generally destroyed or reduced by heat treatment. Potatoes for example may have “solanine” a toxic substance that is destroyed by frying or boiling.

Hope this helps :)

[rwald]

Personally, I like the crunchiness of raw green beens far better than the limpness of cooked ones. But that's a personal choice.

Thanks for the great information, guys! I guess the final verdict is: eat them however you like them, because if you do that, you'll eat more of them, and that's what matters most.

[Liamo]

Originally posted by Jeff Corey
Home grown tomatoes vs winter supermarket tomatoes up north.
I've seen Florida tomatoes picked green to be shipped north. Is it true that they flood them with carbon dioxide or some other gas to turn the skin red?
The compound they're exposed to is actually ethylene, which they normally produce in minute quantities:
Several factors in addition to maturity at harvest have major impacts on postharvest behaviour and quality of fruit-vegetables. Fruits of group (1) normally produce only very small quantities of ethylene. However, they are very responsive to ethylene and can be damaged by exposure to 1 ppm or higher concentrations. Ethylene exposure accelerates chlorophyll degradation, induces yellowing of green tissues, encourages calyx abscission (eggplant), and accelerates fruit softening. Most of the fruits in group (2) produce larger quantities of ethylene in association with their ripening, and exposure to ethylene treatment will result in faster and more uniform ripening as indicated by loss of chlorophyll (green color), increase of carotenoids (red, yellow, and orange colors), flesh softening and increased intensity of characteristic aroma volatiles. All fruit-vegetables, except peas and sweet corn, are susceptible to chilling injury if exposed to temperatures below 5°C (cantaloupe, lima bean, snap bean), 7.5°C (peppers), 10°C (cucumber, soft-rind squash, eggplant, okra, chayote), or 12.5°C (tomato, muskmelons other than cantaloupe, pumpkin, hard-rind squash). A relative humidity range of 90 to 95% is optimum for all fruit-vegetables except pumpkin and hard-rind squash where it should be 60 to 70%. Atmospheric modification (low oxygen and/or elevated carbon dioxide concentrations) can be a useful supplement to proper temperature and relative humidity in maintaining postharvest quality of some fruit-vegetables, such as tomato and muskmelons.

source (http://www.actahort.org/books/434/434_30.htm)

Check this link (http://www.aboutproduce.com/faq/ethylene.html#q4) for a list of ethylene-producing fruits and vegs.

Liam