Canned Foods, Heart Disease and Diabetes: What You Need to Know

This article was originally published by our friends at Authority Nutrition.

Canned foods are often thought to be less nutritious than fresh or frozen foods.

Some people claim they contain harmful ingredients and should be avoided.

Others say canned foods can be a part of a healthy diet.

This article explains everything you need to know about canned foods.

What Is Canned Food?

Canning is a method used to preserve foods for long periods of time by packing them in airtight containers.

Canning was first developed in the late 18th century as a way to provide a stable food source for soldiers and sailors at war.

The canning process can vary slightly from one product to another, but there are three main steps. These include:

  • Processing: Food is peeled, sliced, chopped, pitted, boned, shelled or cooked.
  • Sealing: The processed food is sealed in cans.
  • Heating: Cans are heated to kill harmful bacteria and prevent spoiling.

This allows food to be shelf-stable and safe to eat for 1 to 5 years or longer.

Common canned foods include fruits, vegetables, beans, soups, meats and seafood.

Bottom Line: Canning is a method used to preserve foods for long periods of time. There are three main steps: processing, sealing and heating.

How Does Canning Affect Nutrient Levels?


Canned foods are often thought to be less nutritious than fresh or frozen foods, but research shows that this is not always true.

In fact, canning preserves most of a food’s nutrients.

Protein, carbs and fat are unaffected by the process. Most minerals and fat-soluble vitamins like vitamins A, D, E and K are also retained.

Therefore, studies show that foods high in certain nutrients are still high in the same nutrients after being canned (1, 2).

Yet since canning typically involves high heat, water-soluble vitamins like vitamin C and vitamin B can be damaged (3, 4, 5).

These vitamins are sensitive to heat and air in general, so they can also be lost during normal processing, cooking and storage methods used at home.

However, while the canning process may damage certain vitamins, amounts of other healthy compounds increase (6).

For example, tomatoes and corn release more antioxidants when heated, making canned varieties an even better source of antioxidants (7, 8).

Changes in individual nutrient levels aside, canned foods are good sources of important vitamins and minerals.

In one study, people who ate 6 or more canned items per week had higher intakes of 17 essential nutrients than those who ate 2 or fewer canned items per week (9).

Bottom Line: Some nutrient levels may decrease as a result of the canning process, while others can increase. Overall, canned foods can provide comparable nutrients to their fresh or frozen counterparts.

Canned Foods Are Affordable, Convenient and Don’t Spoil Easily


Canned foods are a convenient and practical way to add more nutrient-dense foods to your diet.

The availability of safe, quality foods is lacking in many parts of the world. Canning helps ensure people have access to a wide variety of foods year-round.

In fact, virtually any food can be found in a can today.

Also, since canned foods can be stored safely for several years and often involve minimal prep time, they’re incredibly convenient.

Additionally, they tend to cost less than fresh products.

Bottom Line: Canned foods are a convenient and affordable source of essential nutrients.

They May Contain Trace Amounts of BPA

BPA (Bisphenol-A) is a chemical that is often used in food packaging, including cans.

Studies show that the BPA in canned food can migrate from the can’s lining into the food you eat.

One study looked at 78 different canned foods and found BPA in over 90% of them. What’s more, research has made it clear that eating canned food is a leading cause of BPA exposure (10, 11).

In one study, participants who consumed 1 serving of canned soup daily for 5 days experienced more than a 1,000% increase of BPA in their urine (12).

Although the evidence is mixed, some human studies have linked BPA to health problems like heart disease, type 2 diabetes and male sexual dysfunction (13, 14).

If you’re trying to minimize your exposure to BPA, then eating a lot of canned food is not the best idea.

Bottom Line: Canned foods may contain BPA, a chemical that has been associated with health problems like heart disease and type 2 diabetes.

They May Contain Deadly Bacteria


While it’s extremely rare, canned foods that weren’t processed properly may contain dangerous bacteria known as Clostridium botulinum.

Consuming contaminated food can cause botulism, a serious illness that can lead to paralysis and death if left untreated.

Most cases of botulism come from foods that have not been canned properly at home. Botulism from commercially canned food is rare.

It’s important to never eat from cans that are bulging, dented, cracked or leaking.

Bottom Line: Canned foods that weren’t processed properly may contain deadly bacteria, but the risk of contamination is very low.

Some Have Added Salt, Sugar or Preservatives


Salt, sugar and preservatives are sometimes added during the canning process.

Some canned foods can be high in salt. While this does not pose a health risk for most people, it may be problematic for some, such as those with high blood pressure.

They may also contain added sugar, which can have harmful effects.

Excess sugar has been associated with an increased risk of many diseases, including obesity, heart disease and type 2 diabetes (15, 16, 17, 18, 19).

A variety of other natural or chemical preservatives may be added as well.

Bottom Line: Salt, sugar or preservatives are sometimes added to canned foods in order to improve their flavor, texture and appearance.

How to Make the Right Choices

As with all foods, it’s important to read the label and ingredient list.

If salt intake is a concern for you, choose the “low sodium” or “no salt added” option.

To avoid extra sugar, choose fruits canned in water or juice instead of syrup.

Draining and rinsing foods can also lower their salt and sugar contents.

Many canned foods do not contain any added ingredients at all, but the only way to know for sure is to read the ingredient list.

Bottom Line: Not all canned foods are created equal. It is important to read the label and ingredient list.

Should You Eat Canned Foods?

Canned foods can be a nutritious option when fresh foods aren’t available.

They provide essential nutrients and are incredibly convenient.

That being said, canned foods are also a significant source of BPA, which may cause health problems down the line.

Canned foods can be a part of a healthy diet, but it’s important to read labels and choose accordingly.

Kris Gunnars is a medical student, personal trainer and someone who has spent years reading books, blogs and research studies on health and nutrition. Kris believes that there is an immense amount of evidence that runs completely contradictory to what the governments and dietitians around the world are recommending. Since starting medical school and becoming a personal trainer, he's learned that the textbooks on nutrition that our future doctors and health authorities read are based on that same faulty or nonexistent evidence. Kris' goal is change that! For more from Kris- Subscribe to Free Updates from his website or click the links above to follow him on Facebook or Twitter.