No. Cooking lowers some nutrients in vegetables and makes others easier to absorb, so neither raw nor cooked wins across the board. Heat and water mainly cost you vitamin C and folate; they tend to release beta-carotene and lycopene and reduce compounds such as oxalate that block mineral absorption. How you cook matters more than whether you cook.
The most useful single dataset on this question is one few people have seen: the USDA's Table of Nutrient Retention Factors, which records how much of each nutrient survives each cooking method. USDA publishes it for calculating the nutrient content of cooked foods. The numbers below come from it, alongside the studies that measured what the body actually absorbs.
What heat and water take away
A retention factor is the share of a nutrient still present after cooking, compared with the same food raw. A value of 55 means 55 percent is left. These are USDA's figures by food type and method.
| Cooking method | Vitamin C | Folate | Thiamin | Potassium | Beta-carotene | Iron |
|---|---|---|---|---|---|---|
| Leafy greens, boiled in water to cover, drained | 55% | 60% | 80% | 85% | 95% | 95% |
| Leafy greens, boiled in a little water, drained | 60% | 65% | 85% | 90% | 95% | 95% |
| Leafy greens, boiled, cooking water kept | 70% | 75% | 90% | 100% | 95% | 100% |
| Leafy greens, stir-fried | 85% | 85% | 90% | 100% | 90% | 100% |
| Leafy greens, baked | 70% | 75% | 90% | 100% | 95% | 100% |
| Other vegetables, steamed | 85% | 85% | 90% | 100% | 95% | 100% |
| Other vegetables, boiled in water to cover, drained | 75% | 65% | 80% | 90% | 90% | 95% |
| Other vegetables, stir-fried | 85% | 80% | 90% | 100% | 90% | 100% |
| Root vegetables, steamed | 75% | 80% | 90% | 100% | 90% | 100% |
| Root vegetables, baked | 75% | 80% | 90% | 100% | 95% | 100% |
| Tomatoes, boiled or baked | 95% | 70% | 95% | 100% | 95% | 100% |
Three patterns stand out. First, the losses are concentrated in the water-soluble vitamins, vitamin C, folate and thiamin; minerals and beta-carotene barely move. Second, the worst case in the whole table is leafy greens boiled in plenty of water and drained, which keeps only 55 percent of the vitamin C and 60 percent of the folate. Third, keeping the cooking water, as in a soup, recovers much of that: the same greens keep 70 percent of vitamin C, 75 percent of folate and all of their potassium.
The reason is leaching. A 2005 University of Wyoming study of vegetable oxalate found essentially all of the oxalate lost during boiling could be recovered from the cooking water. USDA's figures show water-soluble vitamins behave the same way: keep the water and more of them stay with the food.
The same thing in USDA food data
USDA FoodData Central lists raw and boiled versions of most vegetables. Vitamin C shows the pattern most clearly.
| Vegetable | Vitamin C, raw (per 100 g) | Vitamin C, boiled and drained (per 100 g) | FoodData Central IDs |
|---|---|---|---|
| Kale | 93.4 mg | 17.8 mg | 168421, 169238 |
| Broccoli | 89.2 mg | 64.9 mg | 170379, 169967 |
| Brussels sprouts | 85.0 mg | 62.0 mg | 170383, 169971 |
| Swiss chard | 30.0 mg | 18.0 mg | 169991, 170401 |
| Spinach | 28.1 mg | 9.8 mg | 168462, 168463 |
| Carrots | 5.9 mg | 3.6 mg | 170393, 170394 |
Read this table as direction, not precision. Raw and cooked entries come from separately sampled foods, and cooking changes the water content, so a per-100-gram comparison is not a clean before and after. That is why the retention table above is the better guide to how much survives.
What heat gives back
If vitamin C were the whole story, raw would always win. It is not, because several important nutrients are locked inside plant cell walls, and heat and mechanical breakdown release them.
| Nutrient | Study | What was found |
|---|---|---|
| Beta-carotene, from carrots and spinach | Rock et al., Journal of Nutrition, 1998. 8 women, two 4-week periods | Eating thermally processed, puréed carrots and spinach raised blood beta-carotene about three times as much as the same amount of beta-carotene from the raw vegetables. The difference between the two periods was not statistically significant (P = 0.09), but only the processed period raised levels significantly above baseline |
| Lycopene, from tomatoes | Dewanto et al., Journal of Agricultural and Food Chemistry, 2002 | After 15 minutes at 88 °C, trans-lycopene rose from 2.01 to 5.45 mg per gram, an increase of about 170 percent, and total antioxidant activity rose. Vitamin C fell by about 16 percent over the same 15 minutes and 29 percent by 30 minutes |
| Carotenoids and antioxidant capacity in carrots, courgettes and broccoli | Miglio et al., Journal of Agricultural and Food Chemistry, 2008 | Boiling and steaming preserved carotenoids better than frying. Measured antioxidant capacity rose in every cooked vegetable, which the authors attribute to a softer structure releasing more of the compounds |
| Oxalate, which binds calcium | Chai and Liebman, Journal of Agricultural and Food Chemistry, 2005 | Boiling cut soluble oxalate by 30 to 87 percent across the vegetables tested. Steaming cut it by 5 to 53 percent |
The oxalate finding matters for spinach in particular. Spinach is high in calcium on paper, but its oxalate keeps most of that calcium from being absorbed. We covered the numbers in what to eat for bone health after menopause.
Where raw wins
The clearest case for raw is in the brassicas, the cabbage-family vegetables such as broccoli, kale and Brussels sprouts. They contain glucoraphanin, which breaks down into sulforaphane when the vegetable is chopped or chewed. Cooking sharply reduces how much of it reaches the body.
In a crossover trial published in the Journal of Agricultural and Food Chemistry in 2008, eight men ate 200 grams of crushed broccoli either raw or cooked. Sulforaphane bioavailability was 37 percent from raw broccoli and 3.4 percent from cooked, and it was absorbed faster. A 2009 study of five cooking methods for broccoli found steaming was the only one that did not cause significant losses of vitamin C and chlorophyll, and it kept the most glucosinolates. Stir-frying lost the most glucosinolates.
Vitamin C is the other reason to keep some vegetables raw. In USDA's data, raw kale has more than five times the vitamin C of boiled kale per 100 grams.
Vegetable by vegetable
| Vegetable | Raw advantage | Cooked advantage | Best bet |
|---|---|---|---|
| Carrots | Crunch; little else, since vitamin C is low to begin with | Beta-carotene is absorbed more readily | Cooked or blended |
| Tomatoes | Vitamin C | Lycopene rises sharply | Both; cooked sauce counts |
| Spinach | Vitamin C and folate | Less oxalate after boiling; more beta-carotene per bite as it wilts | Both |
| Broccoli | Sulforaphane; vitamin C | Easier to eat in volume; carotenoids preserved by steaming | Raw or lightly steamed |
| Kale | Vitamin C, which boiling cuts sharply | Softer texture, easier to eat in quantity | Raw, stir-fried, or in soup with the liquid |
| Brussels sprouts | Sulforaphane | Most people will only eat them cooked | Roasted or steamed rather than boiled |
For a seasonal version of this, with nutrient values per serving, see what fruits and vegetables are in season in fall.
What about frozen and canned?
A two-part review in the Journal of the Science of Food and Agriculture by researchers at the University of California, Davis concluded that nutrient losses in fresh produce during storage and home cooking may be larger than most people assume. Canning and freezing involve an initial heat step that costs some vitamin C and B vitamins. Canned food then holds those nutrients well because oxygen is excluded. Frozen food loses less up front because blanching is brief, though it loses more during long storage as nutrients oxidize. The authors conclude that recommending only fresh produce overlooks the benefits of frozen and canned.
The practical version: frozen and canned vegetables are a legitimate way to eat more vegetables, and the best vegetable is the one that gets eaten.
Which cooking methods keep the most
| Method | How it does on water-soluble vitamins | Why |
|---|---|---|
| Raw | Keeps all of them | No heat, no water |
| Steaming | Among the best: 85% of vitamin C and folate for most vegetables | The food does not sit in water |
| Stir-frying | Similar to steaming for greens in USDA's table, though one broccoli study found it lost more glucosinolates | Short cooking time, no water to drain |
| Soups and stews | Good, if you eat the liquid | What leaches out stays in the bowl |
| Boiling in a lot of water, then draining | Worst: as low as 55% of vitamin C in greens | Vitamins leach into water that is thrown away |
Where SaladPower fits
SaladPower is six whole organic ingredients, spinach, kale, carrot, broccoli, apple and lemon, blended and nothing else, in a pouch that is commercially processed, sealed and shelf-stable. That makes it neither a raw salad nor a pot of boiled greens. It is closest to the "processed and puréed" arm of the Rock study, although we have not tested absorption from our own product and do not claim that study's result for it.
What we can point to is the label. The Nutrition Facts panel is measured on the finished product, as sold, so the numbers already reflect processing. One 8 oz pouch provides 909 mcg of vitamin A, 100 percent of the Daily Value, 16 mg of vitamin C, 20 percent, 5 mg of iron, 30 percent, and 5 grams of fiber, 18 percent, and delivers 2x the USDA daily recommended vegetable intake. The vitamin C from the lemon also helps with iron from plants, which we explain in why vitamin C helps you absorb iron from plants. For how processing is classified, see is SaladPower ultra-processed.
It works as one part of the week alongside raw vegetables and cooked ones.
Frequently asked questions
Are cooked vegetables less healthy than raw?
Not overall. Cooking lowers water-soluble vitamins such as vitamin C and folate, especially when vegetables are boiled and drained. It also makes beta-carotene and lycopene easier to absorb and reduces oxalate. A mix of raw and cooked vegetables covers both.
Which vegetables are more nutritious cooked?
Carrots and tomatoes are the clearest examples. Heat-processed and puréed carrots and spinach raised blood beta-carotene about three times as much as raw in one small trial, and heating tomatoes for 15 minutes increased trans-lycopene by about 170 percent. Boiling spinach also cuts its soluble oxalate.
Does boiling vegetables destroy the vitamins?
It removes some of them, mostly by leaching into the water. USDA retention factors show leafy greens boiled in water to cover and then drained keep about 55 percent of their vitamin C and 60 percent of their folate. Keeping the cooking water, as in a soup, raises that to about 70 and 75 percent.
Is steaming better than boiling?
Yes, for water-soluble vitamins. USDA retention factors show steamed vegetables keeping about 85 percent of their vitamin C and folate, and a 2009 study of broccoli found steaming was the only method tested that did not cause significant vitamin C loss.
Are frozen vegetables as healthy as fresh?
Often, yes. A review from the University of California, Davis found fresh produce can lose substantial nutrients during storage and cooking, while frozen vegetables lose less up front because blanching is brief. The authors conclude that recommending only fresh produce overlooks the benefits of frozen and canned vegetables.
Sources
- US Department of Agriculture, Agricultural Research Service. USDA Table of Nutrient Retention Factors, Release 6. 2007. ars.usda.gov (PDF). Retention codes 3004, 3005, 3006, 3015, 3001, 3784, 3775, 3785, 3464, 3451 and 3751.
- US Department of Agriculture, FoodData Central, SR Legacy entries 168421, 169238, 170379, 169967, 170383, 169971, 169991, 170401, 168462, 168463, 170393 and 170394. fdc.nal.usda.gov.
- Rock CL, Lovalvo JL, Emenhiser C, et al. "Bioavailability of beta-carotene is lower in raw than in processed carrots and spinach in women." Journal of Nutrition. 1998;128(5):913-916. doi:10.1093/jn/128.5.913.
- Dewanto V, Wu X, Adom KK, Liu RH. "Thermal processing enhances the nutritional value of tomatoes by increasing total antioxidant activity." Journal of Agricultural and Food Chemistry. 2002;50(10):3010-3014. doi:10.1021/jf0115589.
- Miglio C, Chiavaro E, Visconti A, Fogliano V, Pellegrini N. "Effects of different cooking methods on nutritional and physicochemical characteristics of selected vegetables." Journal of Agricultural and Food Chemistry. 2008;56(1):139-147. doi:10.1021/jf072304b.
- Chai W, Liebman M. "Effect of different cooking methods on vegetable oxalate content." Journal of Agricultural and Food Chemistry. 2005;53(8):3027-3030. doi:10.1021/jf048128d.
- Vermeulen M, Klöpping-Ketelaars IW, van den Berg R, Vaes WH. "Bioavailability and kinetics of sulforaphane in humans after consumption of cooked versus raw broccoli." Journal of Agricultural and Food Chemistry. 2008;56(22):10505-10509. doi:10.1021/jf801989e.
- Yuan GF, Sun B, Yuan J, Wang QM. "Effects of different cooking methods on health-promoting compounds of broccoli." Journal of Zhejiang University Science B. 2009;10(8):580-588. doi:10.1631/jzus.B0920051.
- Rickman JC, Barrett DM, Bruhn CM. "Nutritional comparison of fresh, frozen and canned fruits and vegetables. Part 1. Vitamins C and B and phenolic compounds." Journal of the Science of Food and Agriculture. 2007;87(6):930-944. doi:10.1002/jsfa.2825.
- SaladPower Nutrition Facts panel, 8 oz pouch.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.
