Much has been written in recent years about the harm in eating too much processed meat and the benefits of eating fish, but, apparently, consumers aren’t getting the message.

Processed meats like salami, bologna and bacon have been linked to an increased risk of stomach and colorectal cancer. They also have the potential to cause cardiovascular damage and shorten your lifespan.

The International Agency for Research on Cancer has classified processed meat as “carcinogenic to humans.”

Eating fish, especially fatty fish, on the other hand, can reduce your risk of heart failure, coronary heart disease, heart attack and stroke, as well as reduce the brain changes associated with Alzheimer’s disease.

This not-too-encouraging picture of the American diet comes from a study by researchers at Tufts University. They looked at data on nearly 44,000 adults in the U.S. who took part in the National Health and Nutrition Examination Survey (NHANES) to study trends in the amount of processed meat, unprocessed red meat, poultry, fish and shellfish eaten over 18 years. They compared data from the 1999-2000 NHANES to data from the recent 2015-2016 NHANES.

Lay Off the Lunch Meat

The amount of processed meat eaten pretty much stayed the same at 6.5 ounces per week. Lunch meat, sausage, hot dogs, ham and bacon were the most commonly eaten processed meats.

The amount of unprocessed meat eaten decreased from 12 ounces a week to 10 ounces a week, mostly due to people eating less beef. Even though beef consumption decreased by nearly three ounces a week, one quarter of U.S. adults continue to eat more than the suggested level of unprocessed red meat.

The good news is that poultry has become more popular, with intakes increasing from nine ounces to just over 10 ounces a week. For the first time, people are eating more poultry than unprocessed red meat.

Fish Doesn't Get Enough Respect

Fish remains a weak spot in the American diet. The amount of fish and seafood eaten stayed the same — four ounces a week, which is half of the recommended amount in the latest government Dietary Guidelines for Americans. Less than 15 percent of people meet the guidelines for fish and shellfish consumption.

Cost is probably one reason many Americans don't eat more fish, and some people may be concerned about mercury contamination in fish like tuna and swordfish, but the benefits of fish far outweigh any potential risk for most people, especially when those fish at the top of the seafood chain are eaten only once a week. Less experiene cooking fish may be another factor.

Perhaps the biggest reason people in the United States don't eat more fish is that we don't fully appreciate its very real health benefits for our hearts and minds.

Perhaps the biggest reason people in the United States don't eat more fish is that we don't fully appreciate its very real health benefits for our hearts and brains. Fish can help reduce the buildup of plaques in our arteries and improve blood flow to the brain, which is sure to reduce the risk of memory problems.

On the other hand, eating too much processed meat is linked to a higher risk of obesity, diabetes, cardiovascular diseases and some cancers. The International Agency for Research on Cancer has classified processed meat as “carcinogenic to humans.” The World Cancer Research Fund/American Institute for Cancer Research and the American Cancer Society have issued guidelines that recommend minimizing the intake of processed meats like bacon, lunch meats, hot dogs and sausage.

It's not hard to get your meat intake more in line with current nutrition guidance. Eat at least two 4-ounce servings of fatty fish a week such as salmon, Albacore tuna, lake trout, sardines, herring and mackerel. Limit how much unprocessed red meat (beef, lamb, pork, venison) you eat to no more than three 3-ounce servings a week — that's a serving roughly the size of a deck of cards. Eat very little or no processed meat. Fill the void with poultry and plant proteins like beans or tofu.

The study is published in the Journal of the Academy of Nutrition and Dietetics.