How Cooking Affects Vitamin A

food preparation and processing can reduce the provitamin A carotenoid content of foods by up to 90%
Deep-frying, prolonged cooking, combining several preparation and processing methods, baking, and pickling (with the possible exception of the pickling of olives) all result in substantial losses of provitamin A carotenoids
β-Carotene is up to three times more available from cooked and pureed than from raw carrots and spinach.

I view this as evidence to be careful with prolonged cooking and to cook things quickly if at all possible.

Cooking Vegetables Can Improve Vitamin Absorption. Heat degradation is minimal.

Here’s a great quora post summarizing that most vitamins do not degrade with most cooking methods.

  • Vitamin A does not degrade below 490 degrees over one hour. It’s very stable and will generally still be around when the vegetable itself is already inedible.
  • Vitamins D, E, and K are unaffected by heat.
  • Thiamine (B1) degrades above 212F, again not much of an issue unless you like your steaks like bricks (medium is 175F).
  • Riboflavin (B2) does not degrade in heat
  • Naicin (B3) and Biotin (B7) do neither
  • Pantothenic Acid (B5) degrades in heat relatively fast, but you’re getting your daily recommended amount (RDA) just by eating.
  • Folate (B9) is easily degraded in heat and is important, especially to pregnant women, because it converts into B12. You get, however, your RDA relatively easily just by eating a normal diet.
  • B6 and B12 do not degrade
  • Vitamin C does degrade but since you’re getting it from fruits, many of which are not being cooked at all, it’s no issue.

As this site says

cooking softens plant cells and improves absorption of carotenoids. 

As this site says

Studies have also found that we only absorb 1-2% of the beta-carotene in vegetables like carrots, but cooking can raise the level we can absorb to over 75% 5

5. Erdman, et al. (1993). “Absorption and transport of carotenoids.” Annual NY Academy of Sciences 691, 76-85.

As this site says…

The bioavailability of beta-carotene and other carotenoids increases several-fold during cooking because heat releases these substance from proteins to which they are bound in foods

I’ve read about cooking increasing vitamin A absorption a few times. I wouldn’t be surprised if other fat soluble vitamins are also more easily absorbed after cooking.

Humans have been cooking for hundreds of thousands of years, and it’s one reason for their ascension as a species. 

I have a preference for cooked vegetables in that I find it much easier to eat a lot of cooked vegetables than it is to eat raw vegetables or even green smoothies. Still, I like both…

The right way to beat eggs via Perfect Scrambled Eggs - Mr Breakfast.com “One of the most important ingredients in scrambled eggs is hardly ever mentioned… air. It would be nice if we could just dollop a Tablespoon of air into the mixing bowl, but for the time-being, incorporating air into beaten eggs requires good old-fashioned elbow grease (or the electric equivalent). The more you whisk — the more air bubbles become trapped in the shaken and unraveling protein of the eggs. As the eggs cook, protein molecules firm-up around the air bubbles resulting in a spongy texture and hopefully full and fluffy scrambled eggs.”
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The right way to beat eggs via Perfect Scrambled Eggs - Mr Breakfast.com

“One of the most important ingredients in scrambled eggs is hardly ever mentioned… air. It would be nice if we could just dollop a Tablespoon of air into the mixing bowl, but for the time-being, incorporating air into beaten eggs requires good old-fashioned elbow grease (or the electric equivalent). The more you whisk — the more air bubbles become trapped in the shaken and unraveling protein of the eggs. As the eggs cook, protein molecules firm-up around the air bubbles resulting in a spongy texture and hopefully full and fluffy scrambled eggs.”

(via Eggs Poached in Tomato Sauce Recipe - Saveur.com) This is a really interesting way to cook eggs: 1/4 cup extra-virgin olive oil5 Anaheim chiles or 3 jalapeños, stemmed,    seeded, and finely chopped1 small yellow onion, chopped8 cloves garlic, crushed1 tsp. ground cumin1 tbsp. paprika1  28-oz. can whole peeled tomatoes,    undrained  Kosher salt, to taste8 eggs1/2 cup crumbled feta cheese1 tbsp. chopped flat-leaf parsley Warm pita, for serving1. Heat oil in a 12” skillet over medium-high heat. Add chiles and onions and cook, stirring occasionally, until soft and golden brown, about 6 minutes. Add garlic, cumin, and paprika, and cook, stirring frequently, until garlic is soft, about 2 more minutes.2. Put tomatoes and their liquid into a medium bowl and crush with your hands. Add crushed tomatoes and their liquid to skillet along with 1/2 cup water, reduce heat to medium, and simmer, stirring occasionally, until thickened slightly, about 20 minutes. Season sauce with salt.3. Crack eggs over sauce so that eggs are evenly distributed across sauce’s surface. Cover skillet and cook until yolks are just set, about 5 minutes. Using a spoon, baste the whites of the eggs with tomato mixture, being careful not to disturb the yolk. Sprinkle shakshuka with feta and parsley and serve with pita, for dipping.
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(via Eggs Poached in Tomato Sauce Recipe - Saveur.com)

This is a really interesting way to cook eggs:

1/4 cup extra-virgin olive oil
5 Anaheim chiles or 3 jalapeños, stemmed, 
   seeded, and finely chopped
1 small yellow onion, chopped
8 cloves garlic, crushed
1 tsp. ground cumin
1 tbsp. paprika
1  28-oz. can whole peeled tomatoes, 
   undrained  
Kosher salt, to taste
8 eggs
1/2 cup crumbled feta cheese
1 tbsp. chopped flat-leaf parsley 
Warm pita, for serving

1. Heat oil in a 12” skillet over medium-high heat. Add chiles and onions and cook, stirring occasionally, until soft and golden brown, about 6 minutes. Add garlic, cumin, and paprika, and cook, stirring frequently, until garlic is soft, about 2 more minutes.

2. Put tomatoes and their liquid into a medium bowl and crush with your hands. Add crushed tomatoes and their liquid to skillet along with 1/2 cup water, reduce heat to medium, and simmer, stirring occasionally, until thickened slightly, about 20 minutes. Season sauce with salt.

3. Crack eggs over sauce so that eggs are evenly distributed across sauce’s surface. Cover skillet and cook until yolks are just set, about 5 minutes. Using a spoon, baste the whites of the eggs with tomato mixture, being careful not to disturb the yolk. Sprinkle shakshuka with feta and parsley and serve with pita, for dipping.

Aging and Longevity – Glycation

Glycation is a process where sugar and protein molecules combine to form a tangled mess of tissue. Glycated tissue is tough and inflexible, leading to wrinkling not only of the skin, but also of important internal organs.

There are two main causes of glycation;

  1. High blood glucose level, and
  2. Eating foods cooked at high temperatures – over 250°F  …. Do not barbecue, fry, grill, roast, [or broil]

I’m pretty healthy in that I prefer to steam and use an oven. Yes an oven temperature can be high, but typically you don’t find black charred over-cookedness like you do on a grill.

This actually made think that I should eat scrambled eggs more so than fried, as fried eggs are often overly cooked on the bottom and undercooked on top, where as the heat/cooking distribution with scrambled is better. I also think they can cook more quickly, although beating in a bowl does take some extra seconds :P