I’m lucky to live in a warm climate with year-round access to fresh produce, but everyone can go to their local farmer’s market or co-op whenever they can and grab the ingredients for a big-ass salad. Is. Farm-to-table cuisine is great, primal is the ideal too, but the reality is that cooking with fresh, local ingredients requires access and time to shop and prepare meals that not everyone enjoys. Well, not always. Many people depend on preserved food for part or all of the year to meet their meat and eating needs, with “preserved” meaning frozen, canned, dried or fermented.
Whenever the topic of canned food comes up, I inevitably come across the question of whether canned vegetables are nutritious, safe, or even primal. (And I inevitably get comments about how we don’t need vegetables at all, which I discuss in my Definitive Guide to a Carnivore Diet.) Sure, the grok wouldn’t have eaten canned vegetables. But modern humans spend almost every minute of every day engaging with technology in ways our ancestors might not have imagined, from highly engineered mattresses with cooling pads to air fryers to regulate our sleeping temperature. The device you are reading this post right now.
So I’m not worried about drawing some primal line in the sand in food canning. However other questions are important. how does Canned food stack up to fresh or frozen?
Are Canned Vegetables as Nutritious as Fresh or Frozen?
It depends on which vegetable and which nutrient you look at, but in general, canning reduces the nutrient content compared to fresh or frozen vegetables. But this is not true across the board. Sometimes, specific nutrients are actually higher in packaged offerings.
Also—and this is an important point—The loss of nutrients due to canning is often lost by the time the food is on your plate. Canning exposes food to high heat, so much of the loss of nutrients is essentially due to the “cooking” that canned food undergoes. Most frozen vegetables withstand only a quick blanching before flash freezing. Thus, if you compare fresh, frozen, and canned vegetables immediately after harvesting and processing, canned usually looks the worst, nutrient-wise. However, research shows that canned vegetables retain their nutrient levels as they sit on the shelves, while frozen and fresh vegetables lose nutrients, bringing them on par with canned. Once you factor in storing and then cooking fresh and frozen vegetables, you may find that the initial disparities are very small because you’re just putting it in your mouth.
Clearly, the best choices are fresh vegetables that are eaten as close to harvesting as possible. The reality, however, is that the produce at your supermarket can be several weeks after it’s been picked, making it less “fresh” than you imagine. There’s also the whole issue of seasonality and regional availability to consider.
Overall, in most circumstances, canned vegetables are going to be as good or nearly as good as grocery store or frozen vegetables in terms of building a nutrient-rich diet.
BPA concerns in packaged foods
Nutrient content isn’t the only consideration when weighing canned versus fresh or frozen vegetables. There is also Cain. I’ve historically avoided canned vegetables at the store because of concerns over BPA in can linings. (Home-canning in jars is different, of course. I’m all for home canning.) BPA is a known endocrine disruptor that has been linked to immune system dysfunction, cancer, reproductive issues, and more. As scientists and health watchdog groups sound the alarm about BPA over the past decade, industry reports suggest that nearly all US manufacturers have moved away from BPA-lined cans.
While this seems like a positive step, the BPA lining was there for a reason: to help prevent corrosion and preserve the food inside. Manufacturers replaced it, by necessity, with other types of ingredients that are believed to be safe—”supposedly” being the operative word here. However, at this point, it is difficult to determine by which manufacturer the ingredients are being used and, more importantly, how they are being tested for safety. Thus, I cannot say with certainty that these new linings are better.
How long do canned foods last?
Food waste is a huge global problem that is costly economically and environmentally. One way we can reduce food waste is by learning what the expiration date on our pantry items really means. According to the USDA, “Best Buy” dates are not about food safety, but about food quality. After those dates, the taste and texture may be affected, but the canned foods are still perfectly edible.
There’s certainly no reason to throw away canned food just because it’s been a week, a month, or even longer. Canned foods are good in your cupboard for up to five years, although you’ll want to use up more acidic items like canned tomatoes within a year or two. Ideally home canned foods should be used within a year.
Just use common sense (and your nose). If the can looks damaged – rusted, bulging or badly dented – it’s not worth the chance. Similarly, if there is a strange smell in the food inside. Changes in texture, slight discoloration, and crystallization are not signs of food spoilage.
For the most part, I continue to opt for fresh, frozen or chilled food in glass packaging when available. The notable exception is canned fish. The convenience of a canned sardine or anchovy, and the benefits of omega-3s they provide, means they still have a standing ovation in my cupboard.
However, some items are difficult to find outside of the can. Cooked beans don’t come frozen (another argument for skipping legumes?), and while they’re easy and economical to prepare from dry, they require preplanning. If beans are a staple in your household, consider preparing larger batches and freezing them in individual portions. Tetra packs are becoming more common for things like stewed tomatoes and soups, but there are questions about their sustainability. They’re technically recyclable, but many recycling facilities don’t have the proper machinery, so they end up in landfills. And glass can be more expensive, which especially matters when groceries are on the rise.
Even if you’re choosing canned foods for reasons of convenience or availability, look for “BPA-free” on the label. Don’t keep canned tomatoes on the shelf for months at a time. This gives the acidity more time to erode the lining. Buy them closer to when you’re ready to use them. The same goes for canned fruit. If you’re keeping food for emergency preparedness, consider dehydrating as an option.
He covers it. I miss something?
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