A guide to ensure maximum nutrient intake from vegetables
I’ve gone back and forth on “raw vs cooked” vegetables for ages, so it’s time I make a guide on the healthiest way to prepare vegetables to ensure maximum nutrient intake.
Last night, I watched in salivating anticipation as my veggies fried in a pan.
I’d thrown together the usual mixture of onion, mushrooms, spinach, zucchini, and eggplant. As they hissed and popped, I asked a disturbing question: “Am I killing off nutrients?”
With my restricted diet, I have to pay close attention to my nutrient intake. If I slack off with my health, I’m rewarded with dizziness, fatigue, low mood, and lack of motivation to do anything. It’s not good for my mental health.
And it got me thinking.
How much is lost when veggies are put to the fire? Are all nutrients leaching into the pan as they lose shape and texture? Surely, there’s some benefit to cooked veggies, otherwise no one would cook them, right? Who wants to eat raw eggplant anyway?
Gross.
Being me, I went and did some research so I can blabber on about it in a blog post.
So let’s science our question: what is the healthiest way to prepare our vegetables?
May be helpful to refer this post on why vitamins are important, as they’ll be mentioned throughout.
Why Do Vegetables Deform With Heat?
In other words, how do veggies become delicious? Can you tell I’m on team “Cooked”?
We’ll focus on pectin, the main ingredient in plant cell walls. Simply put, pectin acts like a glue to hold cells together. When we cook veggies, heat activates an enzyme called pectin methyl esterase (PME) which degrades the pectin, causing the cell wall to lose its integrity. Whether that’s good or bad for the nutrients within… well, you’ll just have to read on.
Fun fact: because of its glue-like properties, we activate pectin with heat and sugar to make jam. The more you know!
There are many ways to prepare vegetables for their healthiest potential so don’t expect a clear-cut answer here… but here’s a guide below based on what we know.
Healthiest Way to Prepare Vegetables: Raw or Cooked?
Asparagus
Eat cooked
One of the most satisfying vegetables to grow (they sprout of the ground like needles!), asparagus contains an arsenal of antioxidants. Steam it, roast it, or grill it to expose vitamins A, B, E, and folate, all cancer-fighting antioxidants. Adding heat to asparagus breaks down its fibrous stalk, making it easier for our bodies to access and digest the nutrients within.
Beetroot
Eat raw
I don’t think I’ve ever cooked beets. I grew up eating them raw, with salt, pepper, and lemon juice, and staining my lips burgundy. Talk about a natural cosmetic! And because of its high fiber content, an effective colon cleanser. Adding heat to beetroot decreases its folate levels which, as we know from THIS post, helps fight hypertension and cancer. Cooking beetroot also decreases its dietary nitrate content, which has been shown dilate blood vessels to boost athletic performance and help with heart disease. Stick with the raw stuff on this one.
Bell Peppers
Eat however you like
Like with most veggies, bell peppers contain a myriad of nutrients. Let’s start with beta-carotene, a carotenoid responsible for the red-orange hue in vegetables (i.e. carrots, pumpkins, apricots). Heat makes beta-carotene more available for the body, which is then converted into vitamin A, a strong antioxidant. In that regard, bell peppers are better cooked. But they also contain vitamin C and folate. While nutritionists debate whether folate is affected by heat in bell peppers, we know vitamin C does degrade if cooked. In this case, bell peppers are better raw. To cover your bases, eat a mix of both. Good thing they’re delicious either way.
Carrots
Eat cooked
We all know eating carrots promotes healthy vision, and we can thank beta-carotene for it. As mentioned under Bell Peppers, beta-carotene is an antioxidant which becomes vitamin A in the body, promoting reproductive health, strong bones, and good vision. Cell walls in carrots are rather tough so adding some heat helps break them down, making beta-carotene more accessible to the body.
Cruciferous vegetables
Eat raw
This fancy term includes broccoli, kale, cauliflower, cabbage, bok choy, Brussels sprouts, collard greens, horseradish, and turnips. All these veggies contain glucosinolate, a natural compound which can fight bacteria, prevent cancer, and protect our nervous system. Numerous studies (here’s one) have found that glucosinolate is heat-sensitive and becomes less bioavailable if cooked at high temperatures. Does anyone enjoy raw broccoli? No. Should we eat them anyway? Yes.
Eggplant
Eat cooked
Here’s a fun fact. Eggplants (or aubergines) belong to the nightshade family. So do peppers, potatoes, and tomatoes. Nightshade vegetables contain solanine, a toxic alkaloid which has neurological and gastrointestinal consequences. The good news is, it’s mostly in the parts we don’t eat, like the leaves, stem, and sprouts. But this doesn’t mean the vegetable itself is free of solanine. Although you’d have to eat a LOT of raw eggplant to initiate a toxic response, better to be safe than sorry. Give it some heat and a bit of oil. It tastes better like that anyway.
Mushrooms
Eat however you like
Because I live in New Zealand now, every time I encounter mushrooms, I hear Pippin in my head. Yes, of course I’m obsessed with Lord of the Rings. Cook mushrooms any way you like, or don’t. There’s a lot of debate here. Some nutritionists claim heat increases antioxidant levels in mushrooms, while others argue the overall nutrient content decreases. Either way, you’re still getting loads of vitamins and minerals. Many opt for cooked because raw mushrooms are coated with agaritine, a toxic compounds which deactivates with heat… but it’s such a trace amount that I have a hard time worrying about it. Ultimately, it’s up to Pippin.
Onions
Eat however you like
So you cut an onion and suddenly, you’re crying. Here’s what happened: causing damage to an onion activates its defense mechanism, prompting enzymes to produce sulfuric compounds. Although these work to thwart insects, they’re quite beneficial to humans. Sulfur compounds can help fight cancer, blood clots, and high cholesterol, but they don’t do well with heat. Conversely, a bit of heat can increase levels of a phytonutrient called quercetin, a powerful antioxidant in the onion’s outer layers. Like with bell peppers, you benefit either way. My rule of thumb: raw red onion with salads, cooked yellow onion with main dishes.
Spinach
Eat however you like
As I mentioned, vitamin C is sensitive to heat so it’s no surprise that cooking spinach decreases its vitamin C content. But raw spinach contains oxalic acid, which increases the risk of kidney stones and harbors calcium, making it less available to the body. So here’s my advice. As long as you’re getting vitamin C somewhere else, it’s best to lightly sauté your spinach with a bit of oil. The oil helps retain folate. The heat kills the oxalic acid, so you can better absorb calcium and lower the risk of kidney stones. You also eat more spinach that way, ensuring high iron intake.
Squash (butternut, pumpkin, zucchini)
Eat cooked
As you know, pumpkin and butternut squash are tough and fibrous, making them difficult to digest when raw. If you guessed they contain beta-carotene due to their orange color, you’d be right! Like with carrots, beta-carotene becomes more available with heat so cooking pumpkin and butternut increases their nutritional value. Zucchini, on the other hand, has fragile cell walls. If boiled, much of its potassium, phosphorus, and vitamin C content leaches into the water, but it still holds on to calcium and beta-carotene. Pick and choose which nutrient you like and eat as appropriate.
Tomatoes
Eat cooked
Although a fruit, I’m including tomatoes here because we treat them like vegetables. Similar to carrots, tomatoes have tough cells walls, broken down by heat. Heat makes lycopene more readily available for absorption. Lycopene is an antioxidant that can help with inflammation, cancer, neurological diseases, and cardiovascular diseases.
So what have we learned here today?
As you’ve read… there isn’t a single answer on the healthiest way to prepare our vegetables.
As you’ll notice, not all vegetables have a definite answer. In fact, there’s a lot of ongoing debate, and for good reason. Not only does nutritional value depend on the vegetable, but also on the method of cooking and the duration.
The reality is, thermal processing can increase the availability of some nutrients while decreasing that of others. I find it best to mix it up and eat in abundance.
But if you choose to cook your vegetables… cook them lightly! We know for certain that high heat for a prolonged time kills off anything useful.
In conclusion… prepare your vegetables gently and you’ll receive their healthiest potential. Because choosing vegetables means you’re already a winner.
Today’s Tunes: Easy by Troye Sivan
