Can it! A case for canned foods

by Lindsay Miller on October 26, 2012

Buy local. Fresh is best. Get your vitamins. Eat your greens. Pass on preservatives. We hear messages all of the time about what to eat and what not to eat. But, in reality, healthful eating is not as simple as knowing “what’s good for you.” The truth is that a whole variety of factors influence our food choices–preference, time, convenience, cost, access, and availability, just to name a few.

Image used under Creative Commons from stevendepolo.

For me, cost is a biggie. As a poor graduate student, I have to be resourceful. I scour Craigslist for paid research participant ads, I buy my gas mid-week in the morning (that’s when it’s cheapest), and I buy a lot of canned foods. Some of my friends and family elicit a patronizing “ohh…” or make a face of disgust when they hear about my cabinet full of cans.  But, I have done my research and found that there is a case to be made for buying and eating canned foods!

A Case for Canned Foods

It is often assumed that canned foods, especially produce, aren’t as nutritionally valuable as fresh produce. However, the difference isn’t as drastic as people may think. According to a review series done by researchers at UC Davis (1), the heating process involved in canning does significantly reduce the nutrient content of canned foods, especially for the more water-soluble and heat-sensitive vitamins, like B and C. But balancing out this effect is that fruits and vegetables are canned at the peak of their ripeness–when they have their highest nutritional value–effectively “capturing” those nutrients and preventing further degradation.

The nutrient content of fresh produce, on the other hand, will degrade over time, and like canned foods, will decline with heating or cooking. The review even concluded that, “by the time a fruit or vegetable is consumed, fresh, frozen, and canned versions may be nutritionally similar, depending on the post-harvest handling and processing treatments.” As the table below shows, some vitamins and foods are more “nutritionally resilient” to the canning process than others.

A summary of some of the data from the UC Davis review.
Notes: Values for canned products are drained, and values are for cooked foods unless denoted with *.

Further, a recent study (2) suggests that canned goods are more nutritionally cost-effective–that is, they give you more nutrient “bang” for your buck. Researchers calculated “total cost per edible portion” by combining product price, the cost of waste, and the cost value of preparation time. Then, they divided that “total cost per edible portion” by the “amount of nutrient available in that portion” for a variety of nutrients, including vitamin A, C, folate, fiber, and protein. They found that “cost-per-nutrient” value, in general, was less for canned foods than for fresh foods.

Wouldn’t want to eat this spoiled fruit…
Image used under Creative Commons by erix!

In addition to being cheap and decently nutritious, canned foods also have a longer shelf-life compared to fresh foods. Unopened canned foods are usually good for 2-4 years after the canning date. Most fresh produce won’t last longer than a month, unless frozen. And eating spoiled fruit and vegetables can lead to some unpleasant consequences, primarily gastrointestinal distress.

 

 


The Cons of Cans…& How to Avoid Them

The use of BPA (bisphenol A) in the lining of canned foods has been a more recent concern, since BPA from the lining seeps into the food product and is then consumed. Exposure to this compound has been linked with a variety of negative health outcomes, including breast cancer, neurologic developmental issues, and reproductive dysfunction. There is still a need for more research examining the effect of canned food consumption on body BPA levels, since existing studies (3) measure urine BPA levels, which may not indicate BPA levels in the body, and also have limited follow-up. While BPA is not currently banned by the FDA for use in bottles and cans, the good news is that many companies–such as Eden’s Organic, Hunt’s, Trader Joe’s, Muir Glen, and Campbell’s–have tuned into the research and started to manufacture (or are planning to manufacture) using BPA-free materials.

One of the main nutritional concerns of canned goods is the traditionally high sodium levels. However, many brands are now offering reduced sodium and sodium-free options. Additionally, draining the canned product can remove much of the sodium content. Other high-sugar syrups and juices can likewise be drained out to reduce this not-so-healthy aspect of canned food items.

A USDA scientist examining a home-canned product with botulism (left).
Image used under Creative Commons from USDAgov

Although very rare, botulism (contamination due to the toxin-producing bacteria Clostridium botulinum) is one of the more serious dangers of canned food items. To avoid this potential health risk, the U.S. Department of Agriculture recommends disposing of cans that are “bulging, leaking, rusting, badly dented” or cans with a foul odor.

Another drawback of canned foods is that they are generally not locally-produced. For those who value eating and buying local, there’s really no getting around this one–it’s an undeniable con of most canned foods.

***

Of course, the case for canned foods is strongest if we are to think of health in a holistic way, considering dimensions like financial and emotional well-being. For individuals like myself looking to save money, save time, and maximize the shelf-life of my groceries, buying canned foods can be a reasonable alternative to buying fresh produce. Whether or not buying canned is right for you, well, that’s up to you!

Don’t forget to recycle your cans…or use them to build a train!
Image used under Creative Commons from madmarv00.

 

Sources:

1) Rickman JC, Barret DM, Bruhn CM. (2007). Nutritional comparison of fresh, frozen, and canned fruits and vegetables. Journal of the Science of Food and Agriculture, 87, 930-944 & 1185-1196.

2) Kapica C, Weiss W. (2012). Canned fruit, vegetables, beans, and fish provide nutrients at lower cost compared to fresh, frozen, or dried. Journal of Nutrition and Food Sciences, 2(4).

3) Carwille J et al. (2011). Canned soup consumption and urinary bisphenol A: A randomized crossover trial. Journal of the American Medical Association, 306, 2218-2220.

 

*Post updated 10/29/12*

 

Hillary October 26, 2012 at 10:07 am

I would love to see a follow-up for this about frozen food! (That’s how I make my food budget stretch. That and bulk grains :-P)

Lindsay Miller October 26, 2012 at 10:16 am

Hillary,

I make my budget stretch using those strategies too–it’s so much cheaper to buy quinoa (my favorite grain) in bulk. I was hoping there would be interest about frozen foods as well, and I’m hoping to do a follow-up post later in the semester!

Thanks for the comment!

Hillary October 26, 2012 at 8:00 pm

I need to steal some quinoa recipes from you, then. I want to like it because it’s so healthy, but it never turns out quite right.

LeBiochimiste October 30, 2012 at 3:40 pm

My concern with bulk dry goods (especially grains) is that they tend to go rancid over time, and accumulation of oxidized compounds may, on the longer term, be deleterious for the health.

Angela October 26, 2012 at 10:25 am

Hi Lindsay! Thank you for the post. Having gone through food hygiene training as a chef (I worked as a chef while a student), I had always assumed that the high temperatures used in canning killed pretty much everything, so I’m glad they have some value other than longer shelf-life. Luckily, I live next to a market which sells local fruit and veg at prices that are lower than those of canned food (in the UK, canned food prices have risen considerably). I liked the flow and tone of the post, however, I would make the suggestion that you describe within the post, what Bisphenol A is, e.g. that it ‘can leach into food from the protective internal coatings of canned foods’. At the moment, it sounds as if it is an additive that is directly put into the food, and the website you link to is pretty confusing to navigate, with lots of unnecessary data for people who just quickly want to look stuff up. Looking forward to more posts!

Lindsay Miller October 26, 2012 at 11:27 am

Angela,

Thank you for your comment. I am jealous that you live so close to inexpensive fruits and veggies! Your feedback about clarifying BPA is especially helpful, and this weekend I might try to update that segment of my post to better communicate the BPA-canned food connection.

Thanks again!

PF Anderson October 26, 2012 at 12:17 pm

I agree with Hillary – I’d love to see a followup on frozen food and home-canned foods.

I must say I’m very impressed by both the concept, content, and form of this post. I only have one tiny quibble. In the section on BPA, you cite one article but in the text link to two different ones.

CITED:
Carwille J et al. (2011). Canned soup consumption and urinary bisphenol A: A randomized crossover trial. Journal of the American Medical Association, 306, 2218-2220.

LINKED:
1) NPR: Eating Canned Soup Makes BPA Levels Soar: http://www.npr.org/blogs/thesalt/2011/11/22/142672252/eating-canned-soup-makes-bpa-levels-soar

2) How is NIEHS/NTP Researching the Health Effects of BPA: http://www.niehs.nih.gov/health/topics/agents/sya-bpa/#a10614

which links to:
2a) 28 Oct 2009: NIEHS Awards Recovery Act Funds to Address Bisphenol A Research Gaps http://www.niehs.nih.gov/news/newsroom/releases/2009/october28/index.cfm

2b) Bisphenol A-related Journal Articles and Stories http://www.niehs.nih.gov/health/topics/agents/sya-bpa/bpa-related/index.cfm

2c) Birnbaum LS, Bucher JR, Collman GW, Zeldin DC, Johnson AF, Schug TT, Heindel JJ. Consortium-Based Science: The NIEHS’s Multipronged, Collaborative Approach to Assessing the Health Effects of Bisphenol A (25 September 2012) http://dx.doi.org/10.1289/ehp.1205330
http://ehp.niehs.nih.gov/wp-content/uploads/2012/09/ehp.1205330.pdf

Lindsay Miller October 26, 2012 at 4:51 pm

That is poor citation work on my part! I did use the article in the references list, and meant to link to that, but even the abstract couldn’t be viewed in the public domain. So I chose to link to an NPR article discussing the article–then I forgot to change the citation.

As Angela also mentioned above, the BPA link might not have been the best choice, as it is complex and involves multiple sources. Over the weekend I may brush up that segment, as I agree it was poorly explained and supported.

As always, thank you for the feedback–it is so helpful!

Hima October 26, 2012 at 10:56 pm

I’m only 15, so I still live with my parents, and my mom has always been really into buying organic, pesticide-free, all-natural, you name it, but the costs add up pretty fast! Maybe this article will convince her that it’s okay to buy canned sometimes. Maybe I can by myself some new riding boots with the saved money :)

Hima

Gaythia Weis October 29, 2012 at 2:06 pm

I agree with the others above that this is an interesting post. For future expansion, I’d like to see an analysis of “best purchases” for a small number of key vegetables as to which ones have greatest cost/benefit value in which format? Which vegetables preserve (or even release) nutrients when cooked and canned? Which ones are best frozen. Which ones should only be purchased fresh if fresh means fresh rather than after long time lapses since harvest? I’ve seen such guesstimates for pesticide levels but not nutrients.

Lindsay Miller October 29, 2012 at 2:40 pm

Gaythia,

Thank you so much for your comments! While I really wanted to do a more in-depth analysis of best purchases, I also realized including that component would make for an even lengthier blog post. So, I aimed to really just raise awareness of canned food as a legitimate alternative to fresh produce.

That being said, some canned goods with comparable or higher nutrient levels compared to fresh goods include: tomatoes, pumpkin, apricot, green beans, green peas, beets, and beans. However, differences between canned and fresh will vary by nutrient, since Vitamins B and C, for example, are more susceptible to the heating process of canning. In terms of cost-effectiveness, the canned items with the better “cost-per-nutrient” ratios are pinto beans, pumpkin, peaches, and tuna. But again, even this is an over-simplified list, because the cost-per-nutrient varies by specific nutrient in each product!

Unfortunately, there is not a lot of recent literature around nutrient preservation and degradation for specific foods and specific brands, and so much depends on the way in which specific brands process and store their product and they way in which individuals prepare their product. So there really is a lot of variation and it is very difficult to figure out how much nutrient value has degraded by the time the food actually makes it to someone’s plate.

I am currently working on a post about frozen foods for next week, since there seemed to be a lot of interest in how frozen foods compare as well. So stay tuned for that!

Again, thank you for the feedback…there certainly are a lot of questions to explore!

LeBiochimiste October 30, 2012 at 3:42 pm

Lindsay,

Good piece of work. Nice way to “debunk” this popular myth about the significantly lower nutritional value of canned goods over their fresh counterparts. I think you also nicely expose both the pros and cons of boths sides of the medal.

Norm

Elizabeth November 4, 2012 at 11:05 pm

Interesting article. I have a couple of comments:

You said that canned foods tend to have significantly lower values of Vitamins B and C. If we choose to eat canned foods, what are some other things that we could try to eat to make up for the lack of Vitamins B and C? What is the importance of Vitamins B and C?

In terms of happiness and emotional well-being, I think it is important to note that this depends on the person. For example, my roommate just bought a pineapple to make pineapple chicken some time this week. For her, making things from scratch makes her happy. For me, I think this is the most incredible waste of time when you could buy canned pineapples and save a ton of time and effort. But she gets some sort of deranged pleasure out of cooking/baking things the hard way, and I certainly am not going to stop her. The point is, the ‘canned foods are better for your emotional well being’ argument may not hold for everyone.

Comments on this entry are closed.

Previous post:

Next post: