Why Pre-Washed Salad Bags Aren’t Healthy


Bagged salads are a great way to get greens on your plate. So easy to pick up in the supermarket then pop the pre-washed leaves on any meal to make it look healthy.

Unfortunately, they aren’t as healthy as they appear as many contain very little nutrition due to the processing.

pre washed salad leaves

Wilting Before Your Eyes

Pre-packaged salad leaves can stay looking fresh for 5 days in the fridge. However, appearances can be deceptive as the moment something is picked it begins to lose nutritional value.

In some foods, the nutrients can stay around for months like apples and carrots. Others like thin delicate salad leaves once separated individually lose a significant amount of nutrients every hour after being picked.

Pre-bagged salads are packaged along with a mixture of gasses known as modified atmosphere.  This keeps them looking fresh and giving a shelf life of up to a week.

pre washed salad leaves close up

If you check the back of a packet of leaves it will say something like “packaged in a protective atmosphere”. While that sounds nice and helps keep the leaves looking great it doesn’t protect the nutrients.

Once you open a salad bag the leaves often wilt very quickly, this is a true indication of just how much nutrition remains.

People think a few salad leaves on their plate is healthy, whereas it can be more damaging for people to think they are getting nutrition when there’s next to no value in lots of prebagged salads. Only dark green leaves, like rocket or spinach, contain any notable amounts of nutrition.

pre washed salad leaves on display

It’s nice to think when something is prewashed it’s done exactly as you would at home. With fresh water for a few seconds. However the reality is factories that make salad leaves dunk them in an industrial bath of water mixed with chlorine that isn’t changed for hours.

This only applies to airtight salad bags. Kale is often sold in bags but if you have a choice get unwashed and still on the stem that’s packaged with normal air in bags with holes. The kale that’s been chopped and prepared will have been gassed and washed in chlorine.

pre washed salad leaves supermarket

Pre Bagged Salads Are The Most Dangerous

There’s a good reason why salad leaves are washed in chlorine. Salads can contain bugs that cause food poisoning including E coli, salmonella and norovirus. Two were killed in the UK from an outbreak of pre-washed rocket that contained E coli.

The advice following the E coli salad bag outbreak was for all salad leaves, even those pre-washed, to be washed again at home.

As salad leaves aren’t cooked it can be pretty dangerous just opening a bag and putting a few leaves directly on your plate. Some studies have shown that dangerous pathogens can become more virulent once refrigerated.

Professor Pennington is an expert of bacteriology at the University of Aberdeen and has warned that pre-washed salads are one of the products most likely to give food poisoning. His famed quote on bagged salads is “It is generally safer to eat a burger than the salad that goes with it.”

If you’re eating out the vast majority of restaurants in the UK and the US use prebagged salads. Some do make their own from whole leaves, but if it’s a fast, convenience food or a chain then it’s often straight out of a bag.

pre washed salad leaves types

The Healthy Solution To Pre-Bagged Salads

If you have a local grower they often sell washed and prepare salad leaves without any gasses or chlorine. Growers usually select varieties of salad leaves that will naturally last longer without any chemicals. They will be far fresher and more nutritious.

Cut and grow again salad leaves can be grown on a windowsill with very little effort. Make sure to water them and you can have salad leaves in seconds for months.

Choose a good variety that matches where you have the space to grow. Then enjoy really fresh salad leaves while also saving money, plastic and transportation emissions.

nettles in a blender ready to make a fresh juice that’s full of goodness. fresh picked nettles are nutritious due to their deep roots and because they grow wild

Eat some green leafy weeds from the garden like nettles or dandelions. They are full of nutrients as they have to fight to grow and are picked and eaten within minutes. I use some when making a green juice like above.

If you can’t grow leaves then you may want to make a few swaps in order to get vitamins. Frozen peas, frozen spinach or fresh broccoli are almost guaranteed to have way more nutrition per gram than prebagged salads. Eating 20g of green vegetables is far easier for those that struggle with vegetables.

take broccoli out of plastic packet

Photo: broccoli with a tip to make it last longer

Final Thoughts On Pre-washed Salad Bags

  • They’re packaged in gas to last longer on shelves, but the nutrients are lost while they still appear to look fresh.
  • Once opened salad leaves wilt very quickly as they are often a week old.
  • It’s advisable to still wash prewashed salad leaves at home due to the risk of poisoning.
  • Eating green vegetables like broccoli or peas are a far better source of vitamins.

The sad truth is salad leaves that stay looking fresh and healthy for a week in a bag are too good to be true. Like so many other things in life.

I often buy reduced fruit and veg to save money. But would never consider buying a reduced salad bag as by then it will have been picked over a week ago and have next to no nutrition. Don’t be surprised if a salad bag past its date is just slimy and smells like pond water once opened.

Let me know what you think of this article, I know it can be difficult being told that all these healthy foods aren’t that great. But I like to share information to empower people to make better choices.

I do still sometimes have watercress from a bag as it’s now impossible to get it without the bag but I’m aware it may not be as healthy as it looks.

42 thoughts on “Why Pre-Washed Salad Bags Aren’t Healthy”

  1. Omg I so agree!!! I have been getting sick to my stomach, including pain, after eating lettuces from salad bar at work! Thank you for bringing this to light, everyone needs to read this

  2. Gosh, what a disappointment. I’ve been eating the big plastic box full of mixed greens for years now. I eat about 2 cups of those leafy greens every day! Fortunately, I have not gotten sick. I usually prepare 7 jar salads for the week using these greens, along with pre-shredded broccoli slaw, baby carrots, radishes, etc. The convenience of using these big plastic tubs of greens has been an integral part of successfully adding 2 cups of leafy greens to my daily diet. I’m truly sad to learn I have been wasting my time all these years. What will I replace my grab and go salad with? Grab and go raw broccoli just won’t be as appealing. Back to the drawing board.

  3. Omg i eat 1to2 bags a day thinking I was getting all of my vitamin from it, but have been feeling very ill these last few weeks and dizzy and light headed also tummy troubles bloated and wind which is not pleasant at all and being celiac and vegan throght it was good to buy bag leaves. Horrified to learn this so no more bags just buy fresh leaves from now on thank you for explaining regards neet ellway.

    1. Bastian Durward

      Don’t worry I used to do the same, while there might be some goodness in them frozen spinach or fresh broccoli is far more nutritious.

  4. So glad you informed us of this information!
    I’m vegan so I eat a lot of salad.
    Buying in a bag is bed I understand now but what about buying it in a plastic sealed square container like they sell at the supermarket unwashed?

    1. Bastian Durward

      If it’s got airholes you should avoid lots of the issues with this. Living salads still in soil are a good option

      1. Yvonne johnson

        How about the (wonderful?) pre-made salads that Trader Joe’s makes? I take those to work 3 days a week….what I like is I can get variety. I am single and if I bought all those different ingredients to make my own they would go bad before I used them up.

          1. Thanks so much for this information! Are the ones in the plastic containers at Whole Foods okay, or any better?

  5. Exactly the type of article which ends up frustrating normal families and reducing the intake people have. A realistic approach to normal families and the availability of what you’re suggesting as alternatives should show you how dangerous your post is. If you think the average family have time to go out foraging for garden greens and have availability to alternatives at a reasonable price you are far removed from reality.

    1. Bastian Durward

      Hi Rich, I’ve given practical advice in this post that I think is easy for the average person to use – like having frozen peas or broccoli instead. I’m trying to give a full range of advice. I do eat some weeds in green juices rather than buying salad bags and it’s much quicker, but I get not everyone has a garden. Do you have any advice to add? This article was written so that people know that salad bags aren’t actually that good for you and there are much better choices that can be made in the store alone that have way more vitamins per gram.

    2. Agreed. But grocery stores also sell heads of lettuce, unpackaged greens, etc. that yes, need to be washed by the consumer, but aren’t gassed. If anyone has access to a reasonably large grocery store, bagged processed salads aren’t the only option.

    3. 100% believe that these little packets of salad leaves and rocket are RISKY. I wondered why I was constantly getting loadsa gas and so much crampy pain ! After stopping eating this…..WOW >> no gas or pain. BROCOLLI is magic and very beneficial !! Thanx for warning!! XX

  6. Thanks for the information. Please can you refetence your sources as I would like to read more on this subject.

      1. Bastian Durward

        Hi MP, check out the research on salad bags by Cornell University (summarised below). If you have any more research that you think is valid please do let me know.

    1. Bastian Durward

      Hi Alison, If you have access check out the article in the British Journal of Nutrition, summarised below:

      Research has shown that a manufacturing technique used to keep the greens crispy for longer also destroys vitamins and protective anti-oxidants.

      The process, called modified atmosphere packaging, is particularly damaging to vitamin C.

      Levels of nutritious p-coumaric acid, caffeic acid and quercetin are also depleted in bags of salad, the scientists at Cornell University in the U.S. claim.

      The findings, published in the British Journal of Nutrition, mean that shoppers who rely on pre-packed leaves to help them eat the recommended five portions of fruit and vegetables a day are, unwittingly, not having as healthy a diet as they think.

  7. Debbie Ellebruch

    Our local farmer’s markets closed because the EPA said they must wash vegetables on stainless steel to comply with safett standards. Theses farmers have been growing and selling clean delicious stuff for years! Stupid. The EPA would rather we eat the crap on a bag!!!!

  8. Does this apply to spinach? Is buying lettuce thats not in bags but just on the shelf in the refrigerated produce section ok?

  9. A crunchy salad of broccoli, cauliflower, asparagus, radish, onion, tomato, cucumber/courgette etc. all diced up along with fresh lettuce then dressed with olive oil, apple cider vinegar with pepper and/or mustard powder plus possibly a very small amount of honey would seem a better and healthier alternative.

  10. I thought it is a eye opening article on to what i thought is eating better. Ill try to chop my own salads now and incorporate other items. And limit the pre bag kind.
    Thank you

  11. Good article! But I disagree with one small point: “Once you open a salad bag the leaves often wilt very quickly, this is a true indication of just how much nutrition remains.”

    No it isn’t. Wilting is a sign of water loss from cells causing the leaf to lose rigidity, not a loss of minerals and vitamins. If you pick a lettuce from your garden it will wilt in a few hours too. Live plants wilt when they don’t get enough water too, but bounce back when they do get watered (if not too far gone). Plants grown in distilled water don’t wilt even though they are receiving zero nutrients from the distilled water. They won’t grow well, but they won’t wilt.

    You are correct that bagged salad do have fewer nutrients than the original plants though as nutrients are lost over time. But this loss occurs during the days the salad is in the bag, not just when the bag is opened and the CO2 is released.

    For many people in the West struggling to get enough fruit and veg in their diet bagged salad is better than no salad. I guess it’s about compromise :-).

  12. Gas is a big deal though. If most of these salads have brocoli, Brussels sprouts chickory whatever other stuff, if u eat this and think no harm but get all bloated up it’s def better to NOT EAT. Take ur time on eggs or. Hi Len but NO MICROWAVE! It changes chickens composition! Yuk

  13. What is the healthiest way to eat salad greens. Buy a fresh head of romaine or red leaf lettuce and soak in vinegar water for 1-3 minutes? Then allow to dry before putting into a plastic container in the fridge?

  14. I always knew that the lettuce in a bagged package wilts so fast after opening. I was asking that question and found this article on line. So glad for the info. I usually buy head lettuce and will continue to do so, mixing it with other greens. We live in the country so I will try the dandelion greens too.
    Thanks again for all the info.

  15. Thanks for this article. I thought I was doing great by supplementing my dinner with bags of packaged salad leaves. Now I know I’m not getting all the nutritional benefits and that eating pre-packaged, pre-washed vegetables can be detrimental to my wellbeing, I will buy fresh from now on.

  16. I always assumed that prewashed/ bagged salad greens were safe. Thank y’all for clarifying this for me.

  17. The most up-to date research actually suggests that The (harmless) gas used helps to retain the nutrition also, so even though manufacturers use them to retain color, that color retention means nutrition retention. The same research also shows that buying complete heads of greens carries the same risk as pre-bagged salads. So while it’s nice to be able to grow or pick your food, or everyone can or will and only eating spinach and lettuce does not allow enough variety to get all the nutrition you need from leafy greens. Absolutes never work for the majority of people but do turn people away. A better approach would’ve been to suggest a better option is to grow/pick, rather than exaggerate and say the value of pre-bagged is next to nothing because that’s not true.

    1. Bastian Durward

      Hi there, I’ve answered some of these further up. But can you link to the new research? I can only find research that says it harms many of the nutrients?

      Yes whole heads of greens carry the same risk, but the difference is people wash the whole heads of greens and they don’t for the bagged salad.

      That is indeed one of my sets of advice in the article to grow your own or wild pick.

      I think it really does depend on the type of leaves. As watercress has a good amount of nutrition and a decent amount is retained with the bagging. However something like lettuce is low in nutrition to start with, and much lower after being separated, chopped, washed and gassed. That’s what I was referring to with next to nothing, but my opinion could be worded better.

  18. The most up-to date research actually suggests that The (harmless) gas used helps to retain the nutrition also, so even though manufacturers use them to retain color, that color retention means nutrition retention. The same research also shows that buying complete heads of greens carries the same risk as pre-bagged salads. So while it’s nice to be able to grow or pick your food, not everyone can or will and only eating spinach and broccoli does not allow enough variety to get all the nutrition you need from leafy greens. Absolutes never work for the majority of people but do turn people away. A better approach would’ve been to suggest a better option is to grow/pick, rather than exaggerate and say the value of pre-bagged is next to nothing because that’s not true.

    1. Bastian Durward

      Hi there, can you link to this up to date research? I’ve not seen any evidence the “protected atmosphere” retains vitamins. Yes it’s harmless, but the worry is that the food is low in nutrients. The risk is far higher with salad bags because people don’t wash them and several times it’s been salad bags alone linked to an outbreak.

      You do make a good point that broccoli and peas alone may mean people are missing out on some nutrients in leafy greens. I’ve resolved this by adding frozen spinach into that list also.

      I totally get not everyone can grow their own. I was able to with just a tiny room and some cut and grow again salad leaves on the windowsill while in a tiny houseshare or picking some wild greens.

  19. Absolutely outrageous article! There are so many claims here that are exaggerated or simply not supported by scientific evidence, it is shocking.
    If you make a health-related claim, please provide peer-reviewed research that supports that. The author doesn’t, because this is a click-bait, not a fact-based article.
    I am not a fan of washed bagged salads, but please don’t make stuff up – don’t we have a code of practice for journalists/bloggers/etc.?

    1. Bastian Durward

      Hi, the problem is there is no peer-reviewed research, who would fund the tens of thousands to prove beyond doubt that salad bags are less nutritious than say whole lettuces or frozen peas?

      As ideal as it would be to wait for everything to be proven unless there is money it won’t ever happen. It’s known that as leaves are separated from the lettuce they degrade quicker, so a whole lettuce is going to have degraded less and have more nutrients than individual leaves that have been separated, washed in chlorine and packaged in a protective atmosphere. Joanna Blythman in Shopped did some research into this.

      At the end of the day, the article is just saying salad bags aren’t nearly as healthy as many people think and you’d be better off with broccoli or frozen spinach. Yes it can’t be proved scientifically because I don’t have the money, but does it make logical sense? I think so. Of all the advice on the internet I don’t think it’s “shocking”.

      If there’s something you want to disprove with your sources please do, so we can all learn.

  20. While I for all my salad I don’t agree that a modified atmosphere is bad for the vitamins. It is extremely common to use antioxidant gases such as Nitrogen- which cannot be tasted and prevents oxidation of the vitamins. You will not stop the process of decomposition, but that and cool temperatures slow it down.
    I am sure there will be some loss of nutrients, but it is incorrect to make this propaganda without references.
    I’d like to see a proper study done in an academic institution about it.
    Have you read any? Have you measured Vitamin activity or degradation in say 1000 bags? That would prove it.

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