To cook or not too cook? Dr Tim Crowe ex­plores the pop­u­lar claim that raw food is health­ier than cooked — and ex­plains why some foods love a lit­tle heat.

Healthy Food Guide (Australia) - - CONTENTS - Dr Tim Crowe is an Ad­vanced Ac­cred­ited Prac­tis­ing Di­eti­tian and nu­tri­tion re­search sci­en­tist. Con­nect with him at think­ingnu­tri­

Is raw food bet­ter than cooked, or do some foods love a lit­tle heat?

Do you worry that you’re miss­ing out on im­por­tant nu­tri­ents by cook­ing your food? Fear not. Cook­ing causes much less nu­tri­ent loss than you think, and can even make food more nu­tri­tious. Find out why.

The rise of raw di­ets

Raw food di­ets move in and out of pop­u­lar­ity. ‘Go­ing raw’ is un­der­pinned by the idea that cook­ing food de­stroys en­zymes and nu­tri­ents, so you can see why it seems so ap­peal­ing.

A big plus for go­ing raw is you eat plenty of plant-based foods — in all their nat­u­ral and un­cooked glory. Com­pared to a typ­i­cal meat-heavy Aus­tralian diet with too many pro­cessed foods, raw food di­ets are streets ahead in vi­ta­mins, min­er­als, fi­bre and other plant nu­tri­ents.

Does cook­ing lower the nu­tri­tional value of food?

Cook­ing does re­sult in chem­i­cal changes in food and a loss of some nu­tri­ents. But it’s just vi­ta­min C, fo­late and thi­amine that stand out as the main nu­tri­ents lost, and their lev­els rarely drop by half. Most other nu­tri­ents are un­af­fected, or are al­tered by a very small amount.

There are plenty of other foods rich in vi­ta­min C, thi­amine and fo­late to make up for any short­fall caused by cook­ing. Citrus fruits are an ex­cel­lent source of vi­ta­min C. Leafy green veg­eta­bles and av­o­ca­dos are great sources of fo­late. And whole grains come packed with thi­amine, as does bread, due to its for­ti­fi­ca­tion.

What about an­tiox­i­dants?

Look­ing be­yond vi­ta­mins and min­er­als, there are hun­dreds of an­tiox­i­dants found in plant foods that have favourable health ben­e­fits, and the losses of these through cook­ing are small.

In fact, cook­ing in­creases the amount of some of these an­tiox­i­dants. Carotenoids (the pig­ment that gives car­rots and other veg­eta­bles their rich, vi­brant colours) ex­ist in­side cell struc­tures, but they are not eas­ily avail­able. Cook­ing car­rots breaks open the cell walls, free­ing up the carotenoids so that your body can ab­sorb their good­ness. The same goes for toma­toes. Cooked — and canned — toma­toes are much higher in the pow­er­ful can­cer-fight­ing an­tiox­i­dant, ly­copene, than raw toma­toes.

Cook­ing not only max­imises the health ben­e­fits of some foods — it also im­proves the foods’ safety by what it takes away. Cook­ing at 75°C or hot­ter kills most of the bac­te­ria that cause food poi­son­ing.

Put the heat on

So, what’s the best way to re­tain the most nu­tri­ents from food dur­ing cook­ing? The three keys are water, tem­per­a­ture and time. As tem­per­a­ture, cook­ing time and water vol­ume in­crease, so too do nu­tri­ent losses. Steam rather than boil, if pos­si­ble, as this re­duces nu­tri­ents leach­ing into the water. In fact, the or­ange water left af­ter boil­ing car­rots sig­nals the loss of nu­tri­ents.

Cook at lower tem­per­a­tures where pos­si­ble, or at a higher tem­per­a­ture for a shorter time, as when quickly stir-fry­ing. Keep the size of veg­etable pieces as large as you can to min­imise ox­i­da­tion losses. And don’t over­cook food: you want your broc­coli to emerge firm and green, not wilted and white.

Mak­ing sense of it all

An em­pha­sis on eating mainly plant-based foods close to their nat­u­ral state is in­dis­putably good for your health, no matter how they are cooked. Worry less about how much vi­ta­min C your veg­eta­bles are los­ing from a stir-fry din­ner, and fo­cus more on hav­ing plates that are full of colour­ful, nu­tri­tious foods.

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