What you need to know about processed meats

processed-meatsThe consumption of processed meats has been linked to a higher risk of developing heart disease and cancer by many studies, which is why eating these foods is considered unhealthy.

The nutrients in fresh, natural meats can play a positive role in the diet, but processed meats like bacon, hot dogs, and salami have added chemicals to enhance flavor and preserve freshness.

If a meat is smoked, cured, salted, dried or canned, it’s been processed. Meats that have been frozen or mechanically processed, such as cutting, slicing or separating, do not usually have added chemicals.

Here are some examples of processed meats:

  • Beef jerky and other dried meats
  • Bacon and ham
  • Sausage, hot dogs, salami
  • Smoked and canned meats
  • Corned beef and other salted, cured meats

Processed meats have been associated with detrimental effects for decades; health-conscious people usually steer clear of them

Observational studies, which don’t provide hard evidence, indicate that people who live unhealthy lifestyles tend to eat more processed meats.

For example, people who smoke usually eat more processed meats and fewer vegetables and fruits than people who make healthier choices. (1, 2)

It’s hard to argue with the strong association between processed meat consumption and a higher risk for developing chronic diseases. Let’s look at some of the reasons why you may want to pay attention to the link.

Potential Health Effects of Processed Meats

While it’s not clear whether eating processed meats leads to health problems, this list shows some of the issues that develop with more frequency in those who partake:

  • Stomach and bowel cancer (3, 4)
  • Heart disease (5)
  • Hypertension (high blood pressure) (6)
  • COPD (chronic obstructive pulmonary disease) (7)

Observational studies cannot prove that people who regularly eat processed meats developed these health conditions as a direct result of dietary habits, but animal studies support the hypothesis.

One study showed that rats consuming processed meats developed bowel cancer at significantly higher rates than those who didn’t. (8)

Researchers believe the N-nitroso compounds in processed meats are responsible for effects that can lead to health damage.

These substances come from the added sodium nitrite added during processing. Here’s nitrites are added:

  1. Flavor is improved because nitrite suppresses the oxidation of fat; in other words, it doesn’t turn rancid as quickly.
  2. The red or pink color of meat is preserved in the finished product, and it retains color even with aging.
  3. Bacterial growth is inhibited, which decreases the chance a consumer will get food poisoning.

Nitrite and other similar compounds are not always harmful; in fact, generous amounts are found in certain vegetables and can impart health benefits in their natural state. (9)

But the nitrates in vegetables don’t change into harmful compounds like the ones found in processed meats. Nitrosamines are the most widely studied of these substances. (10)

While most of the dietary nitrosamines ingested today come from processed meats, other sources include pickled and salted foods, contaminated drinking water, and tobacco smoke. (11)

Cooking Methods Matter

The majority of nitrosamines are formed when meat is exposed to high heat greater than 266° F (130° C).

As mentioned above, animal studies confirm a greater risk of bowel cancer when processed meats are eaten regularly, and observational human studies support these findings. (12)

Smoking meat has been a popular preservation method for centuries, and is often used in combination with salt and drying techniques.

This type of preparation also leads to the formation of harmful compounds, including polycyclic aromatic hydrocarbons (PAHs). (13)

PAHs form when organic matter is burned; these substances transfer into the air when food is cooked over an open fire. Even if meat isn’t directly exposed to flame, PAHs build up on the surface. (14)

Smoke and heat from burning charcoal and wood trigger the formation of PAHs; the vapors and smoke from fat that drips down onto hot surfaces and permeates food above, leaving high concentrations of PAHs. (15)

Animal studies indicate that certain PAHs cause cancer, and scientists believe PAH’s may be responsible for some of the adverse health effects attributed to processed meats. (16)

And there’s more: heterocyclic amines (HCAs) are yet another group of harmful substances that form when fish or meat are subjected to high temperatures, such as during grilling or frying. (17)

HCAs don’t occur only in processed meat, but significant amounts are found in products like hamburger patties, fried bacon and sausages. (18)

While monkeys exposed to HCAs developed cancer, they were given much larger amounts than would normally be present in a typical human diet. (19)

Human observational studies indicate people who regularly consume foods with HCAs run a higher risk of colon cancer, as well as breast and prostate cancer. (20, 21, 22)

When food is cooked at lower temperatures, like steaming or gentle pan-frying, the amount of HCAs is significantly lower.

Processed meats are also often high in sodium chloride, otherwise known as table salt. The most common use of salt is to improve taste, but it has also been used extensively for preservation throughout history.

Typical modern diets include a range of processed foods besides meat that are generously dosed with salt, so adding salty meats on top of that can elevate sodium intake to the point where it impacts health.

Eating a lot of salt can be disastrous for individuals with salt-sensitive hypertension since it results in high blood pressure, a known marker for developing heart disease. (23)

Observational studies also indicate excessive salt consumption can raise the risk of developing stomach cancer. (24)

High salt levels in the stomach encourage the growth of helicobacter pylori, the bacterium that causes ulcers. The formation of ulcers is a known risk factor for stomach cancer. (25)

Salting foods lightly to enhance flavor is not likely to cause problems for most people, but eating plenty of foods high in salt content could increase the chances of developing various chronic diseases.

Recap

Eating whole, fresh foods is the best strategy for cultivating overall good health; this includes meats as well as fruits, vegetables, and other foods dominating your diet.

Summary: Occasional consumption of processed meats is acceptable for most people, but avoiding the harmful compounds formed in these foods the majority of the time is a smart move to increase your chances of enjoying good health.

References:

  1. http://www.ncbi.nlm.nih.gov/pubmed/15829014
  2. http://www.ncbi.nlm.nih.gov/pubmed/23497300
  3. http://www.ncbi.nlm.nih.gov/pubmed/15956652
  4. http://www.ncbi.nlm.nih.gov/pubmed/16550597
  5. http://www.ncbi.nlm.nih.gov/pubmed/20479151
  6. http://www.ncbi.nlm.nih.gov/pubmed/8621198
  7. http://www.ncbi.nlm.nih.gov/pubmed/17255565
  8. http://www.ncbi.nlm.nih.gov/pubmed/20530708
  9. http://www.ncbi.nlm.nih.gov/pubmed/19439460
  10. http://www.ncbi.nlm.nih.gov/pubmed/9306073
  11. http://www.ncbi.nlm.nih.gov/pubmed/8972287
  12. http://www.ncbi.nlm.nih.gov/pubmed/16865769
  13. http://ec.europa.eu/food/fs/sc/scf/out154_en.pdf
  14. http://www.ncbi.nlm.nih.gov/pubmed/24910314
  15. http://link.springer.com/article/10.1007%2Fs11694-013-9147-2
  16. http://ec.europa.eu/food/fs/sc/scf/out154_en.pdf
  17. http://www.ncbi.nlm.nih.gov/pubmed/19369370
  18. http://www.ncbi.nlm.nih.gov/pubmed/9651045
  19. http://www.ncbi.nlm.nih.gov/pubmed/7959450
  20. http://www.ncbi.nlm.nih.gov/pubmed/15051825
  21. http://www.ncbi.nlm.nih.gov/pubmed/10944558
  22. http://www.ncbi.nlm.nih.gov/pubmed/16357191
  23. http://www.ncbi.nlm.nih.gov/pubmed/22110105
  24. http://www.ncbi.nlm.nih.gov/pubmed/21160428
  25. http://www.ncbi.nlm.nih.gov/pubmed/17510398
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