don't zap your veggies

[Guest guest]

I'm always concerned, when I hear these discussions about the nutrient

losses when raw vegetables are cooked, about something that I keep asking

myself. Are these simply quantitative nutrient losses, that occur when

vegetables are cooked? Or does the quality of those nutrients that are not

lost with a cooking method, suffer as well? These nutrients are simply

molecules of various sorts, and I wonder if they are altered or degraded by

the application of high heat levels.

Even if 100% of a vitamin or other nutrient was retained during a cooking

method, high heat might still degrade the quality of that nutrient so that

it's usefulness in the body would also be compromised.

JP

-

" Elizabeth Miller " <ecmillerreid

<Mr_Tracys_Corner >; <ginmee;

<alternative_Medicine_Forum >

Thursday, October 16, 2003 9:05 PM

don't zap your veggies

 

 

http://www.healthatoz.com/healthatoz/Atoz/news/hs515591.html

Veggies Lose Antioxidants in the Microwave

 

 

Blanching and freezing also robs them, study finds

By Amanda Gardner

HealthDay Reporter

 

THURSDAY, Oct. 16 (HealthDayNews) -- Getting the necessary nutrients

from vegetables may be even harder than you thought.

 

New research shows that different ways of preparing, storing and

processing vegetables can affect how good they are for you.

 

Broccoli, for instance, can lose as much as 97 percent of some

antioxidants, or cancer-fighting compounds, when it is zapped in the

microwave.

 

Vegetables that are blanched before freezing (a common processing

technique) can lose up to one third of their antioxidants. Frozen

storage can also cause losses, albeit much smaller ones.

 

Two studies detailing these findings appear in the November issue of

the Journal of the Science of Food and Agriculture .

 

Antioxidants are plentiful in vegetables and work to eliminate free

radicals, which can damage cell DNA and contribute to various diseases.

That's why eating fiber, fruits, and vegetables, all of which contain

antioxidants, can help prevent cancer and cardiovascular disease.

 

As it turns out, though, that protective effect is most pronounced when

the vegetable is in its natural state.

 

The first study found that the simplest cooking method was also the

worst when it came to preserving nutrients. Broccoli lost 97 percent of

flavonoids, 74 percent of sinapics and 87 percent of caffeoyl-quinic

derivatives (three different types of antioxidants) when it was

microwaved.

 

When boiled the conventional way (i.e., not in a pressure-cooker), this

green lost 66 percent of its flavonoids; when tossed in a pressure

cooker, broccoli lost 47 percent of its caffeoyl-quinic acid

derivatives.

 

Steamed broccoli, on the other hand, lost only 11 percent, 0 percent

and 8 percent, respectively, of flavonoids, sinapics, and

caffeoyl-quinic derivatives.

 

The advantage of steaming vs. conventional boiling is that you're " not

using water directly in contact with the vegetable. The nutritional

compounds don't go into the water, " says Cristina Garcia-Viguera, lead

author of this paper. " Once the compounds are in the water, the

temperature destroys them much easier. "

 

A microwave wreaks havoc because it heats the inside of the vegetable.

That, combined with the fact that you normally use water when

microwaving, causes the destruction of valuable nutrients.

 

Even reheating steamed broccoli in a microwave would probably have the

same effect, Garcia-Viguera says, although she did not specifically

examine this in her research.

 

The findings can probably be extrapolated to many other vegetables but,

again, the researchers did not specifically address this.

 

The second study looked at the effects of blanching and freezing and of

long-term freezer storage on more than 20 common vegetables. As it

turned out, different species showed different effects from these

processing techniques.

 

In general, dietary fiber components were not affected or even went up

slightly. Mineral content, also, tended to remain stable.

 

On the other hand, antioxidant activity went down 20 percent to 30

percent during blanching.

 

Carrots, peas, and broccoli lost 30 percent of their vitamin C during

blanching/freezing, while green beans lost 10 percent and spinach lost

40 percent (with an additional 30 percent lost during deep frozen

storage).

 

Spinach also lost almost 40 percent of its potassium and 70 percent of

its folic acid during blanching.

 

Don't despair just yet, says Samantha Heller, a senior clinical

nutritionist at New York University Medical Center in New York City.

 

The use of these vegetables in the studies meant they were nutritious

in the first place, she says. " Then I'm still reaping the benefits

even if they're losing some of their qualitative values, " she says.

 

Moreover, Heller points out, not all of the healthy properties of

vegetables are being eliminated. " You're still getting plenty of

healthy compounds as well as fiber, so there's absolutely no reason not

to eat vegetables -- although, of course, the fresher the better, " she

says.

 

" If people are willing to have vegetables anyway, shape or form, even

if they are going to nuke then, I'd rather have them do that, " she adds.

 

More information

 

For more on eating enough fruits and vegetables, visit the Centers for

Disease Control and Prevention . The American Dietetic Association has

a series of nutrition fact sheets.

 

What goes on when you microwave food? Read about it at HowStuffWorks .

 

Sources: HealthDay

 

2003 ScoutNews, LLC . All rights reserved.

 

 

[Guest guest]

In " Thorsons Complete Guide to Vitamins & Minerals " (3rd ed 2000) there is

a long multi-page entry about losses of vitamins in food processing.

 

============

A summary of the entry is:

 

1. Some loss of vitamins is inevitable but, except for the examples quoted

below, most losses are small.

 

2. Manufacturing losses, when they occur, are sometimes comparable to those

in domestic cooking losses.

 

3. When foods are further cooked at home, losses of vitamins are additional

to those incurred during the manufacturing process.

 

4. It is easier and more convenient to recover vitamins clustering domestic

cooking (e.g. by utilizing cooking water) than those lost in factory

processing.

 

5. The importance of the losses in a particular food must be considered in

relation to the whole diet. When the food makes only a small contribution

to the intake of vitamins, processing losses it may not be significant.

However, losses from foods that make up a significant part of the diet,

like milk and cereal products for babies and cereals in some countries, can

cause serious deficiencies in those relying on such diets.

 

6. Some processing methods confer nutritional advantages on the vitamin

content of food, e.g. thiamine inhibitors in some vegetables are destroyed

by cooking and nicotinic acid is liberated from its inactive bond of form

by the cooking of cereals.

 

7. Under processing of some foods may not destroy harmful microorganisms in

those foods. Processing can improve appearance and flavor of some foods and

allow preservation for all around the year availability the ideal

conditions of food processing allow these advantages with only minimal

distraction and loss of vitamins.

 

========

In the entry on " losses of vitamin C in storage " , Thorsons describes the

loss of vitamin C in potatoes once they leave the ground and are stored:

 

Main crop, freshly dug contain 30 mg per 100 g.

After 1-3 months storage contain 20 mg per 100 g.

After 4-5 months storage contain 15 mg per 100 g.

After 6-7 months storage contain 10 mg per 100 g.

After 8-9 months storage contain 8 mg per 100 g.

 

 

Losses of Vitamin C in cooking can be minimized by keeping the volume of

water low. Much of the vitamin C can be recovered from the cooking water by

utilizing it in sauces, gravy, etc.

========

 

 

 

At 01:33 AM 10/18/2003 -0700, John Polifronio wrote:

 

>I'm always concerned, when I hear these discussions about the nutrient

>losses when raw vegetables are cooked, about something that I keep asking

>myself. Are these simply quantitative nutrient losses, that occur when

>vegetables are cooked? Or does the quality of those nutrients that are not

>lost with a cooking method, suffer as well? These nutrients are simply

>molecules of various sorts, and I wonder if they are altered or degraded by

>the application of high heat levels.

>Even if 100% of a vitamin or other nutrient was retained during a cooking

>method, high heat might still degrade the quality of that nutrient so that

>it's usefulness in the body would also be compromised.

>JP