How does canned food affect your body? A balanced look at health impacts

According to a 2015 study published in the journal Nutrients, frequent canned food users had a higher intake of 17 essential nutrients compared to those who consumed fewer canned goods. This surprising fact challenges the common perception and raises important questions about how does canned food affect your body.

Quick Summary

This article explores the nutritional benefits and health risks of canned foods, including nutrient retention, potential exposure to BPA, and high levels of sodium and sugar, to help consumers make informed dietary decisions.

Key Points

• Nutrient Retention: Canning preserves most nutrients like protein, fiber, and fat-soluble vitamins, though some water-soluble vitamins are lost.

• Increased Antioxidants: The high-heat canning process can increase the antioxidant content in some foods, such as lycopene in tomatoes.

• High Sodium & Sugar: Many canned foods contain added salt or sugar for preservation and flavor, which can contribute to health issues.

• BPA Exposure: Some can linings contain Bisphenol A (BPA), an endocrine-disrupting chemical that may leach into food and pose health risks.

• Gut Health: Processed and ultra-processed foods can negatively affect the gut microbiome, and BPA exposure has been shown to alter gut microbes in studies.

• Safety Precautions: Avoid consuming food from damaged cans (dented, bulging) due to the rare risk of botulism.

• Healthier Choices: Opt for low-sodium or no-salt-added cans, choose fruits in water or juice, and rinse canned items to reduce additives.

The Canning Process and Its Nutritional Impact

Canning is a food preservation method where food is processed and sealed in airtight containers, which are then heated to kill harmful bacteria. This process extends shelf life and can make many nutritious foods accessible and affordable year-round. However, it is not without its trade-offs.

Nutrient Retention vs. Loss

During the high-heat canning process, most macronutrients (protein, carbs, fat) and many fat-soluble vitamins (A, D, E, and K) are well-preserved. A 2015 study found that frequent canned food consumers had higher intakes of several essential nutrients like fiber, calcium, and iron. However, some water-soluble and heat-sensitive vitamins, particularly vitamin C and B vitamins, can be degraded by the heat. It is important to remember that these vitamins can also be lost during cooking at home.

Increased Antioxidant Content

Interestingly, the heat from canning can sometimes enhance the bioavailability of certain healthy compounds. For example, cooking or canning tomatoes significantly increases the amount of lycopene, a powerful antioxidant linked to heart health and a reduced risk of prostate cancer. Canned corn also releases more antioxidants when heated.

Potential Health Risks of Canned Foods

While many canned foods offer great nutritional value, certain risks are associated with some products, depending on how they are processed and packaged.

High Sodium and Added Sugar Content

For preservation and flavor, many canned foods are packed in brines or syrups, which can dramatically increase their sodium and sugar content. Excessive sodium intake is a major contributor to high blood pressure, and high sugar consumption is linked to obesity, type 2 diabetes, and heart disease. Careful label reading is essential for identifying and choosing low-sodium or no-salt-added options. Rinsing canned vegetables and beans can also help reduce sodium levels.

BPA Exposure from Can Linings

Bisphenol A (BPA) is a chemical used in the epoxy resins that line the inside of many metal cans to prevent corrosion and food spoilage. BPA is a known endocrine disruptor, meaning it can mimic human hormones and potentially affect health. Research has linked BPA exposure to conditions like heart disease, diabetes, obesity, and reproductive issues. BPA can leach from the can lining into the food, and studies have detected it in a significant percentage of canned goods. To minimize exposure, consumers can look for cans explicitly labeled “BPA-free,” although the safety of alternative linings is not always clear.

Risk of Botulism

Botulism, a severe form of food poisoning, is an extremely rare but life-threatening risk associated with improperly canned foods. It is caused by the toxin-producing bacteria Clostridium botulinum. Commercially canned goods are very safe, but home-canned products pose a higher risk if not processed correctly. Never consume food from a can that is dented, bulging, cracked, or leaking, as this can indicate spoilage.

Impact on Gut Health

The gut microbiome can be negatively impacted by excessive consumption of ultra-processed foods, which can include certain canned items high in additives. Animal studies have also shown that BPA can alter gut microbes. Some nanoparticles used in can linings have been shown to affect nutrient absorption and trigger inflammation in laboratory cell cultures, although the long-term effects on human gut health are not yet fully understood. Prioritizing whole foods and limiting ultra-processed items is recommended for better gut health.

Making Healthier Choices with Canned Foods

Canned foods are an undeniable convenience, but mindful consumption is key to maximizing their benefits while minimizing risks. Here are some actionable tips:

• Read the label: Look for “no salt added” or “low sodium” on vegetables and beans. For fruits, choose varieties packed in water or 100% fruit juice instead of syrup.
• Rinse canned goods: Draining and rinsing canned beans and vegetables can significantly lower their sodium content.
• Choose BPA-free packaging: Look for cans labeled “BPA-free” to reduce chemical exposure.
• Inspect cans for damage: Avoid any cans that are dented, bulging, or leaking to prevent the risk of botulism.
• Incorporate fresh and frozen: Strive for balance by including fresh and frozen foods in your diet, which retain all their water-soluble vitamins.

Comparison Table: Canned vs. Fresh/Frozen

Aspect	Canned Foods	Fresh Foods	Frozen Foods
Convenience	Highly convenient; pre-cooked, minimal prep	Requires washing, peeling, and cooking	Convenient; pre-chopped, quick to cook
Shelf Life	Very long (1-5 years or more)	Short; degrades over a few days to weeks	Long; lasts for several months
Nutritional Content	Retains most nutrients; may lose some water-soluble vitamins. Some antioxidants may increase.	Highest in water-soluble vitamins if consumed soon after picking.	Retains most nutrients due to quick freezing.
Additives	Often contains added salt, sugar, or preservatives.	None (unless added during preparation).	Minimal to none; check for added sauces or seasonings.
Chemical Concerns	Potential for BPA leaching from can linings.	None from packaging.	Generally low risk, but can contain BPA in certain plastics.
Cost	Often more affordable, especially for out-of-season items.	Can be expensive, especially out of season.	Often more affordable than fresh produce.

Conclusion

Canned food's effect on your body is not a simple matter of good or bad. It is a nuanced topic with both benefits and risks. Canned goods offer a convenient, affordable, and often nutritious option that can help meet daily nutritional needs, especially in areas with limited access to fresh produce. However, concerns regarding high sodium and sugar content, alongside potential BPA exposure from can linings, warrant a cautious and mindful approach. By reading labels, choosing low-sodium or BPA-free products, and incorporating a variety of fresh and frozen options, canned foods can be a healthy and valuable component of a balanced diet. Ultimately, the impact depends on the specific product and how it is incorporated into your overall eating habits.

For more information on nutrition and healthy eating, visit the Academy of Nutrition and Dietetics.

Frequently Asked Questions

Is canned food less nutritious than fresh or frozen food?

Not necessarily. While some heat-sensitive, water-soluble vitamins like C and B can be lost during the canning process, most other nutrients, including fat-soluble vitamins, minerals, protein, and fiber, are retained. In some cases, like with tomatoes, canning can even increase antioxidant levels.

What is BPA and why is it a concern with canned foods?

BPA, or Bisphenol A, is a chemical used in the lining of some food cans. It is an endocrine disruptor, meaning it can mimic human hormones. BPA can leach into food, and studies have linked exposure to potential health issues like heart disease and diabetes.

Are all canned foods high in sodium?

No. While many canned foods use salt as a preservative, a wide variety of 'low sodium' or 'no salt added' products are available. Draining and rinsing canned beans and vegetables can also reduce their sodium content significantly.

Can I reduce the added sugar in canned fruit?

Yes. To reduce sugar intake, choose canned fruits packed in water or 100% fruit juice instead of heavy or light syrup. Draining and rinsing can also help remove some of the sugar.

What is botulism and how can I avoid it with canned foods?

Botulism is a severe, life-threatening food poisoning caused by bacteria. It is extremely rare in commercially canned foods but can occur in improperly processed items. You can avoid it by never eating from cans that are dented, bulging, or leaking.

Do canned foods affect gut health?

Highly processed canned foods can negatively affect the gut microbiome, while BPA exposure has been shown to alter gut microbes in animal studies. Choosing less processed options and incorporating fresh foods is beneficial for gut health.

How can I make healthy choices when buying canned foods?

Read the labels carefully, opting for 'no salt added' or 'low sodium' products. Choose fruits packed in water or juice instead of syrup. Look for cans explicitly labeled 'BPA-free' to minimize chemical exposure.