Does Cooking Boost Nutrients in Tomatoes and Spinach?

Sep 01, 2017 · 82 comments
kj (nyc)
I usually make simple soup broth with my vegetables, add pre poached chicken and brown rice for a full meal and at the same time consume all the vitamins that were leached out.
Jay David (NM)
One nice thing about Well is that you actually have to use your brain a little. In most NY Times articles that give and discuss advice, the reader is urged to avoid using her or his brain as much as possible to become a robot. The following article is a good example of what I mean: TRAVEL | TEST RUN How to Explore a City Like a Local Using Your Smartphone By JUSTIN SABLICH SEPT. 8, 2017
pewter (Copenhagen)
I'm forever missing analyses on baked vegetables!! Baking vegetables in a circulating-heat oven (I forget what that setting is called) has become my favorite way of cooking vegetables. I put them in the oven directly from the freezer, spread out on a cookie sheet (no lining necessary). No oil is used, and I only add salt when they're done after approx. ten minutes at 400 degrees Fahrenheit (200 Celcius). They taste far better this way and can be tossed hot with all sorts of spreads to give them extra flavor.
jimi99 (Englewood CO)
There is also the oxalic acid factor in cooking spinach or eating it raw.
dredpiraterobts (Same as it never was)
So, let's say you gently cook the tomato with the skin on. And lets say the skin doesn't break (To save us from splitting the hairs of percentage loss) are all the vitamins still in the tomato? And has the predigestion of cooking released the lycopenes? What about if I cut the tomato in half and grill it? And, are you saying that Spaghetti sauce is better for you than a tomato sandwich... mmm... tomato sandwich... sliced thick, with fresh garlic butter, mayonnaise, fresh ground black pepper, on multi grain bread... mmm... excuse me, I just thought of something, I gotta go...
Al B (North Carolina)
No mention of glucosinolates, the primary anti-carcinogenic compound in broccoli. Studies show that steaming is preferable to long cooking periods or microwaving.
Paul (Los Angeles)
What about steaming? I steam fresh spinach. It packs an energy punch that way.
Tokyo Tony (<br/>)
see the last paragraph
David Binko (Chelsea)
Packs an energy punch???? Anyway, if you missed it, they do mention steaming in the last sentence of the article.
ken hernandez (pittsburgh)
Most vegetables should be converted into vitamin pills ... cooking and eating should mainly involve meat and "empty" carbs, except where something is required for taste balance (like pickles and onions on a burger or tomato sauce on a pizza..
EHL (Denver, CO)
How about a high speed blender? I think that breaks down the cell walls allowing for more nutrients to be absorbed.
Beaconps (CT)
I cook most of my tomatoes because they taste better. If I were making a rice bowl with cherry tomatoes, I would add them as the rice finishes.
Wind Surfer (Florida)
This another scientific reference on lectin toxicity.
"Dietary Plant Lectins Appear to Be Transported from the Gut to Gain Access to and Alter Dopaminergic Neurons of Caenorhabditis elegans, a Potential Etiology of Parkinson’s Disease

imageJolene Zheng1,2*, imageMingming Wang1, imageWenqian Wei3,4, imageJeffrey N. Keller2, imageBinita Adhikari5,6, imageJason F. King7,8, imageMichael L. King7,8, imageNan Peng4 and imageRoger A. Laine7,8"

http://journal.frontiersin.org/article/10.3389/fnut.2016.00007/full
CAK (Keene, NH)
Some clarification for those who may be intimidated by this lengthy scientific study or unfamiliar with interpreting the diagrams and charts that represent the results of what was actually studied: the researchers were looking specifically at Parkinson's, and their work looked at very specific and isolated lectins that were fed in highly concentrated doses (not the plant as humans/animals would consume it) to one type of bacterial cell. Let's stop the fear-mongering. The chances of the average person developing PD because they ate too many rice and bean dishes versus the probability of developing pre-diabetes, diabetes, hypertension, coronary artery disease, and general inflammation associated with obesity from consuming the usual American diet are next to zero. How are you benefiting from the fear-mongering?
skramsv (Dallas)
Every human is unique. Many people with IBS and other inflammatory digestive system diseases get worse with eating plant based diets, especially plants that are eaten raw. Most people would be better off if they stopped eating anything made from soybeans. It is also important to keep in mind that what geographical region a person comes from is important. If your ancestors got by eating mostly meat, you will do better on a meat diet.

But the real thing is cooking food can be beneficial and this is based in real chemistry and has been well studied for decades. Eat everything in moderation and remember that animal fat and protein are needed to be healthy.
pewter (Copenhagen)
Animal fat and animal protein are not "needed to be healthy." I'm on year six eating only vegan food and I've never felt or looked healthier. I look ten years younger than I did five years ago.
Wind Surfer (Florida)
Many self-claimed experts comment that lectins, the plant toxins, are safe because we have been eating plants for centuries. However, changing environment by excess usage of chemicals and over-usage of drugs have created leaky guts for many people. This is another scientific research summary on the toxicity of lectins.

" Peanut lectin stimulates proliferation of colon cancer cells by interaction with glycosylated CD44v6 isoforms and consequential activation of c-Met and MAPK: functional implications for disease-associated glycosylation changes.
https://www.ncbi.nlm.nih.gov/pubmed/16571666
pewter (Copenhagen)
"Eating plants for centuries"?? Try hundreds of millions of years!

I think you should look at processed foods as a far more likely cause of leaky gut than plants and peanuts.
D. Shiffman (Baltimore)
I read the comment that no one boils vegetables today and that roasting is now very popular, both observations of which I agree. Compared with the other methods of cooking, what does roasting do to the vitamins and minerals in various vegetables? The roasting method means that the vegetables are usually basted in oil and cooked at at least 400 degrees.
J Jencks (Portland)
Often I'll cook a pot of brown rice and put veggies, chopped into bite size pieces on top as the water boils down. This steams them nicely and the aromas of the veggies and rice combine deliciously... a slice of cheese over the top 1 minute before it comes off the stove, some salt and pepper ... mouthwatering!

It also saves me from having to wash 2 pots.

;o)
Joanne (Boston)
Yum! I'm going to try this twice - once in a regular pot on the stove, the second time in a pressure cooker or maybe a slow cooker. Thanks!
Wind Surfer (Florida)
I am attaching one of the medical reference on the toxicity of lectins.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1115436/

I am also attaching an interview of Dr. Dale Bredesen of UCLA/UCSF, a well-respected Alzheimer's researcher and also a pioneering therapist of app. 100 Alzheimer's patients with remarkable success in the memory restoration.
He discloses his adoption of Dr. Gundry's lectin-elimination diet as a trial test for his Alzheimer's patients.

https://www.youtube.com/watch?v=p6lkRXaQKwk
CatPerson (Columbus, OH)
I visited a gastroenterologist for a time when I was having severe bouts of IBS. He explained to me that it's best to cook your vegetables because, not being rabbits, we are better able to digest them. I assume, too, that we can absorb the nutrients better. The raw veggie thing is not good. I took his advice and my IBS attacks are very rare now, maybe every couple of years, and always associated with stressful events in my life.
Wind Surfer (Florida)
Autoimmune diseases takes years and years of patients' time from antibody creation to the disease recognized as "disease". According to Dr. Tom O'Bryan, a functional medicine doctor well informed in autoimmune diseases, even most researched "celiac disease" usually requires patients 5 doctors and 11 years to finally being recognized as "autoimmune disease called celiac disease" by the 5th doctor. He includes "lectin" as one of the antigens (causing immune reactions) in addition to famous "gluten" and "dairy". I admit that "lectin" is so far under-researched, and that some doctors declare "lectins" and "gluten" are not serious causes of diseases because of their ignorance. I know Dr. Steven R. Gundry is ridiculed as a fad doctor because of his warning of "lectins". However, Dr. Dale Bredesen, a well-respected researcher of Alzheimer's at University of California has initiated testing of a therapeutic diet developed by Dr. Gundry to his Alzheimer's patients, even though Dr. Bredesen has diets that he has developed for years. So Far, Dr. Bredesen has shown remarkable recoveries from early Alzheimer's patients (about 100 now). Why does Dr. Bredesen try to test Dr. Gundry's diet in such an important time? I presume that (1) he recognizes the fact that lectins cause chronic inflammation (one of the major cause of Alzheimer's), and that (2) he wants to improve his recommended diet to Alzheimer's patients.
Megan (Santa Barbara)
Jeez, who boils vegetables? Oven-roasted veggies are so much more delicious....
Joanne (Boston)
I never boil vegetables. But too many roasted veg isn't good for some of us because of the extra calories from the olive oil. So I often steam them, and eat them plain (still delicious, although I agree roasted is the yummiest). For additional flavor I sprinkle with lemon juice, herbs etc. at the table.

Steaming is also fast, and pots are easy to clean - just rinse!
MaryO (Boston)
I often boil vegetables -- briefly, for a few minutes. Usually asparagus, broccoli, or green beans. Then dress the veggies with good olive oil, lemon, sea salt and freshly ground pepper. It's a lot faster than roasting them, if you want to get dinner on the table quickly.
pewter (Copenhagen)
I never use oil on my oven vegetables, it's not at all necessary. I take them straight from the freezer and into the oven.
Nasty Man aka Gregory, an ORPi (old rural person) (Boulder Creek, Calif.)
My mom always thought to save the water that boiled something with, for the "vitamins". She went through the depression era
Jeanne DePasquale Perez (NYC)
Also known as pot liquor-
sjs (Bridgeport, CT)
Both are delicious raw or cooked. Eat both and solve the issue.
J (USA)
I can't eat cooked tomatoes or spinach. I get esophageal spasms from them. But raw both are fine. Can anyone explain this?
tew (Los Angeles)
Perhaps a doctor
Matthew (UWS)
What is an esophageal spasm?
sjs (Bridgeport, CT)
I can't drink milk, but I can eat anything made from milk. I have no explanation for that. The heat in cooking maybe?
Mrs. Chippy (<br/>)
I think there's too much neurotic thinking surrounding these of kind of nutrition 'issues.'

If you eat lots of plants--both raw and cooked--, whole grains, well-assimilated protein, and a variety of fruit, you've got the basics of a healthful diet, one that will help prevent many chronic diseases.

If you keep hydrated, exercise aerobically to keep your heart strong, lift weights to maintain muscle mass, you've got a relatively easy plan for keeping your body well tuned.

This is not rocket science; it's just plain common sense.
Tim (Alaska)
Uncommon common sense.
K Henderson (NYC)
Mrs chippy -- Not true if folks are eating veggies out of cans which are generally salted and soggy just off in about every way. But otherwise sure I can agree.
Joanne (Boston)
As Michael Pollan says: "Eat food. Not too much. Mostly plants."
Son Of Liberty (nyc)
Using two examples out of all the vegetables we eat is the dumbest way to make an argument implying that you should be cooking vegetables rather than eating them raw. Congratulations! This is really a way to use anecdotal evidence to make arguments without using science and is perfect in the time of Trump.
Englewood Steve (Englewood, NJ)
Even the HEADLINE says Tomatoes and Spinach so I don't understand the rant.
Reenee (Ny)
Clearly, in the age of Trump, the article should have been about how Trump prefers his vegetables. He does seem energetic.
dve commenter (calif)
I rarely eat tasteless red tennis balls any more. It seems no matter what the cost, tomatoes are nothing more than roller bearings for some heavy duty machinery. It would also have been nice to read a RECENT lab test of the nutrients in your example "tomato". Color me skeptical. Every food product but raw produce is enhanced with vitamins from A to Z. If food had any real nutritional value, WHY ADD ALL THE VITAMINS?
Ravenna (NY)
Studies show (and so does google) that Organic tomatoes, though smaller, have more nutrients than "tennis ball" tomatoes. They taste better too.
sylviag2 (Palo Alto, California)
Not sure where in CA you live but several markets near me offer dry farm tomatoes, usually beginning in August. They are fabulous and taste the way tomatoes used to taste from my grandmother's garden growing up in Ohio.
Jeannie (WCPA)
I grew my own this year and they are delicious.
ChesBay (Maryland)
Well, regardless I eat both, cooked and uncooked.
David (Irving, TX)
Blurbs like this are akin to examining a pine needle in a forest. There are so many aspects to health. Genetic variance of innumerable metabolic enzymes among individuals, exercise, environment, diet, exposure to toxins (smoking, excess alcohol). Virtually every reader would do much better to go for a twenty minute walk than worry (or read) about whether a vegetable is "more nutritious" cooked or raw. Further, spinach and tomatoes are NOT the only source of these nutrients. One could, I dare say, live to the century mark having never had either cross their lips.
MPH (New Rochelle, NY)
If you are eating plenty of Tomatoes and Spinach you're doing better than most - raw or cooked.
Aussie (Celebration, Florida)
Slow, pan roast a halved tomato and it enhances its flavor tenfold. It is no surprise, therefore, that it also increases its levels of lycopene
L.Braverman (NYC)
What about eggs? Hard boiled? Soft boiled? I hate soft boiled but eat at least 1 hard boiled egg a day, in my salad. Has it lost nutritional value by being boiled?

Sometimes when I'm busy I leave the eggs in the previously boiled water for up to an hour before I get around to shelling them. Leaving them there that long; Is that harmful to the nutritional value of the egg? Once I shell them, I put 1 egg in the salad and 1 in the fridge for the next day; that egg in the fridge: is that losing nutritional value there? If so, how much & how quickly? How long can I keep it in the fridge before it has lost all its nutritional value? Thanks.
Menno Aartsen (Seattle, WA)
I do not believe eggs are a vegetable
wbj (ncal)
Thank you for solving that mystery.
Karen (Los Angeles)
Carrots provide more nutrition
when cooked.
Harriet Squier (Lansing, MI)
While that is true, it should also be remembered that Vitamin A is a fat soluble vitamin, which means the body stores whatever is absorbed, which means it is possible to get too much of this vitamin, as the body cannot excrete it easily if we ingest too much. Cooked carrots occasionally are a great source of easily absorbed vitamin A, but if you start eating them every day, you might be at risk for vitamin A toxicity. Even eating a raw carrot every day can turn you orange from the beta carotene. Drinking carrot juice every day is likely to become toxic. So bottom line, everything in moderation.
dve commenter (calif)
which means it is possible to get too much of this vitamin,
and, TOO MUCH can cause blindness.
Davide (Pittsburgh)
To say that high consumption of carrots can cause vitamin A toxicity is naive at best. Carrots provide β-carotene, a precursor of vitamin A (retinol). When an individual already has generous amounts of vitamin A, the gut ceases β-carotene conversion, and the excess is absorbed or excreted, harmlessly in either case, unless you count yellowed skin as "harm."
Jeffrey Waingrow (Sheffield, MA)
I believe you've left out a third alternative which I use almost exclusively, namely steaming. That way, you've cooked the vegetables but there's no leaching of nutrients. I find that a very quick steaming of most but the toughest vegetables is sufficient.
Jeff Swint Smith (Mount Pleasant, Texas)
I also use steaming almost exclusively, and have been very pleased with the results.
Karl (Melrose, MA)
There's a fourth alternative: sous vide.
DW (Ohio)
Did you read the last paragraph?
James (Portland)
This excellent reminder underscores the benefits of eating a whole food plant based diet that uses a variety of cooking techniques. We eat tons of vegi's in the form of salads, soups, pizza (with cashew cheese yum!), stir-fry, and just as a snack. If you only get your vegi's one way or occasionally two ways, then you really are missing out on some excellent nutrition.
Tom (Manhattan)
Vegi's? What does the vegi own?
dejhanaWHS (raleigh)
It’s interesting that foods can get nutrients pulled out when cooked while others don’t.
Karl (Melrose, MA)
"Raw spinach provides a lot of fiber"

... and the same amount it provides once it's cooked...
Petey tonei (Ma)
My 90 year old-school physician mom has somehow been brainwashed into thinking microwaving food is harmful. Somewhere she heard that it was so bad that you shouldn't even feed your enemy microwave cooked food.
Charley horse (Great Plains)
Well, she has made it to 90. Maybe she knows something.
Menno Aartsen (Seattle, WA)
Boiling foods in water is an early technology to help heat and make fibers digestible, actually requires lots of artificial things, like a heating element or flame, and a pot, and water, but boiling is a technology nevertheless, just as microwaving is. It is true one should not eat food while it is being microwaved, and microwaving one's enemies is equally reprehensible (but then, so is boiling 'em).
Ravenna (NY)
She may be on to something:
http://www.mercola.com/article/microwave/hazards2.htm

Sorta like Climate Change it takes a while for Science to overcome Commerce.Even doctors smoked back in the day.....
ghsalb (Albany NY)
Leafy greens like spinach have many important anti-oxidants besides just the familiar beta carotene. Lutein and zeaxanthin help combat macular degeneration and its resulting vision loss: http://www.mayoclinic.org/diseases-conditions/dry-macular-degeneration/m... These *might* be increased by cooking, but it would help if this was spelled out. This is extremely important for anyone who wants to retain their vision into old age.
Rea Tarr (Malone, NY)
I've been eating lots of greens -- dark ones; lots of raw spinach -- for years. Have now lost most of the vision in one eye due to macular degeneration.

Perhaps we should be cautious in saying that "anyone who wants to retain their vision into old age" should eat leafy greens.
Wind Surfer (Florida)
Probably 99% of the readers are not informed of the danger from lectins (toxins from plants and gluten is one of them). Tomatoes and other New World plants like corn, or whole wheat, whole rice, legumes, tree nuts and almost all the plants carry lectins. (source: The Lectin Report (web) by Krispin Sullivan and The Plant Paradox (book) by Steven R. Gundry) It is generally better to cook (pressure cooking is best) in order to break lectins. They mostly concentrate in seeds and skins. These lectins and, once passing gut membrane and usually riding on dangerous lipopolysaccharide, attach to cell membranes causing more than 80 different autoimmune diseases that lead to degenerative diseases (most of them also called as mitochondrial metabolic diseases). People suffering from leaky guts usually suffer from lectins. Lectins are less known in comparison with gluten, but they are as dangerous as gluten. If you want to eat a tomato, they advise to remove skin and seeds.
Dr. J (CT)
Wind surfer, can you provide any sources for your claims? Because lectins may also have beneficial effects. " We have known for over half a century that lentils and beans have the highest levels of lectins and therefore can make us sick if we eat them raw ["Toxicity of raw kidney beans", Jaffe WG, Experientia 5 (1949) 81]. We also know that cooking beans for 15 min at 100 C or 2 hrs at 80 C completely denatures lectins, and canning beans is just as effective, meaning cooked and canned legumes are not only completely safe but their residual lectin levels fight cancer and fungal / bacterial / viral infection [Thompson LU et al, J Food Science 48 (1983) 235; Dhurandhar NV & Chang KC, J Food Science 55 (1990) 470; Xia L & Ng TB, J Chromatography 844 (2006)." http://drclydewilson.typepad.com/drclydewilson/2011/02/paleo-diet-is-inc...
Still Waiting for a NBA Title (SL, UT)
Most people, just like with gluten, can eat all of the naturally occurring lectins they want with no noticeable ill effects. That is, of course, unless you are new age or a hipster. In those case I am pretty sure it will kill you. But fret not, you can still consume all of the LSD, magic mushrooms, PBR, and overhopped beer you want.
Wind Surfer (Florida)
Dr. J,
All the sources are references in The Lectin Report and The Plant Paradox as I mentioned. I am glad to debate this area with informed people like you, not like nonsense comment like "Still Waiting for a NBA Title." This is the new area and a lot of unknown medical conditions are buried.
carllowe (Huntsville, AL)
The real answer to whether or not cooked vs. raw vegetables are better is to eat some of both. That's the best of both vegetarian worlds.

And if you steam your vegetables, drink the water you steamed them with. It's a warm, refreshing vegetable broth. Season to taste.
David Morgan (Montana)
So, our natural tendency to have raw veggies in warm seasons (e.g. salads) and cooked veggies in the cool seasons (e.g. soups/stews) should do it! :)
Steven (Las Vegas)
After steaming veggies, I store the water in the frig and use it as the base liquid for my smoothie the next morning.
Doug Rife (Sarasota, FL)
This is really not as important as the question of whether eating fruits and vegetables. cooked vs. raw, is best for long term health. A recent study finds that raw vegetables are better than cooked while fruits are better than vegetables. But there is a limit to the value of fruits and vegetables with consumption of just 3-4 servings per day yielding the lowest relative risk while higher intake provides no additional benefit.

What's more, based on international data involving 135,000 people across five continents, high carbohydrate diets are associated with high mortality while moderately high fat diets are not. This finding directly challenges the common belief that high fat diets are unhealthy even if they may reduce weight gain. HIgher fat intake was associated with lower mortality including all fats even saturated fat which was also associated with lower stroke risk.

The highest mortality rates were found in countries where very low fat diets are the norm.

http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(17)32253-...

For more details not covered in the abstract see this:

https://www.sciencedaily.com/releases/2017/08/170829091027.htm
Chronicler (Minneapolis)
Moral of the story: continue to source as many calories as possible from: legumes, grains, nuts, fruits, and vegetables. This is easily done in 'developed countries' where access to these foods are easy, meaning malnutrition from lack of certain vitamins or fats is not likely.

Also, your second paragraph of conclusions is not correct and it was not stated in the study that you've linked. The Science Daily is not a credible source.
Dr. J (CT)
Doug Rife, have you read the original article? I can only open the abstract; the article is behind a paywall. Until I can read the article, I tend to take everything "with a grain of salt" -- skeptically.
PT (Wisconsin)
Science Daily is a compendium of research news taken from directly from science journals (abstracts) and news releases from University and Government research labs. It is thus as credible -- or not -- as the research it reports.