Can the Human Body Digest Red Meat?

Red meat is often on the list of foods to stay away from, especially if you're hoping to watch your weight, cholesterol and heart health. But red meats, if eaten properly, can also be great sources of amino acids, protein, iron and vitamins. Here's how to eat red meat in moderation.

Eating meat certainly isn't a new trend. In fact, humans have been eating meat for millions of years, according to Nature. Bringing meat into the human diet about 2.6 million years ago actually marked a distinct evolutionary change for us.

Similar to the chimpanzee diet, the diet of early humans included things like fruit, leaves, insects, meat and even elements of trees like bark and roots. Nuts and seeds, the closest fat-rich foods next to meat, were also a part of their diet. It's likely our ancestors began eating meat because it's packed with vital amino acids and micronutrients, and it helped humans boost body size while maintaining mobility and agility.

It turns out the human body had to develop the digestive ability to consume meat through evolution as well. Because our ancestors were used to subsisting off the gatherer diet of vegetables, fruit and seeds, eating meat triggered a change in how human digestion worked as well.

It's likely that back then, people simply didn't eat as much meat as they do now, however. Now, we know that red meat takes longer to digest than other foods — which can be good for satiety, but not as good for gut, heart and overall health.

When you've consumed meat, it goes through various phases starting with your mouth and saliva, acidic gastric juices in the stomach and the small intestine. As meat travels through the gastrointestinal tract, a January 2017 study published in ‌Comprehensive Reviews in Food Science and Safety‌ writes, it goes through various processes that contribute to oxidative stress.

Oxidative stress is an imbalance between free radical production and antioxidants, and has been linked to diseases like cancer. It's possible that heme iron, which is found in red meats, and high levels of fat can all contribute to an increase in oxidative stress in the digestive system.

Oxidative stress can result in inflammation, damaged DNA, cytotoxicity and impairment of microbiota, or gut bacteria. It's one of the reasons red meat is now so often linked to health problems and chronic diseases.

‌Read more:‌ 10 Steak Recipes That Any Carnivore Will Love

Before discussing the health risks of red meat, however, there are a few good things about it that should be taken into account. At the end of the day, red meat does hold the greatest amounts of iron compared to most other foods (particularly heme iron, which is the kind that's absorbed at the highest levels).

It's also a big source of valuable protein and essential nutrients, according to an August 2016 study published in ‌Proceedings of the Nutrition Society‌. If you're looking to increase protein in your diet, red meat takes the cake over other meats, seafood or plant-based proteins.

A smaller, denser amount of red meat contains more protein than a cup of lentil soup, for example. A piece of ribeye steak is pretty much all protein and fat, containing nearly 40 grams of protein (up to 76 percent of your daily value) and plenty of saturated fats and cholesterol.

These positive aspects of red meat are what makes it a popular part of the ketogenic diet. Organic, grass-fed red meats like beef and lamb are often protein bases in this diet that's high in fat and low in carbohydrates.

The keto diet aims to trigger the body into a state of ketosis, where it burns more fat than normal. That's because removing carbs (and the subsequent boost in blood sugar after eating them) from the body causes cells to have to rely on stored fat for energy, according to Harvard Health. As a result, you have to eat a great deal of meats and fats in order to sustain your energy levels. That could include red meat like beef, or eggs, cheeses, seafood and oils.

There's also continued debate over whether this high-protein and -fat diet is healthy for you. Harvard Health notes that there's some evidence showing that a keto diet can have neuroprotective effects, reducing seizures in children and possibly being beneficial for brain diseases. More research in humans, however, will need to be carried out in order to further test these ideas. And though some advocates for the keto diet claim it may potentially treat obesity and type 2 diabetes, there's still not enough solid evidence to support it works.

‌Read more:‌ The Carnivore Diet: Is Going All-Meat Right for You?

Especially in recent years, research questioning the health benefits of red meat has grown. A lot of it depends on the type of red meat you're eating as well. Red meat refers to meat that's a red color when it's raw — including beef (from cows), pork (from pigs) and veal (from calves).

There are a variety of factors that go into producing meat. It starts with how the animal is raised: Many cows are raised in factories, feed off grain-based meals and have loads of hormones and antibiotics injected into them. Afterwards, their meat products can go through high levels of processing, including the addition of chemicals, nitrites, sodium or preservatives.

It's these highly processed meats that tend to contribute to health issues, when eaten in large amounts over long periods of time. One December 2018 study in the ‌European Heart Journal‌ found that frequently eating red meat was linked to high levels of trimethylamine N-oxide (TMAO), a chemical found in the gut that's associated with heart disease.

That study found that people who ate plenty of red meat in their diets saw three times the amount of TMAO in their bodies. Eating a lot of red meat has also been linked to an increased risk of cancer, as well as increased risk of mortality. There's also a chance you get stomach pain after eating red meat, if you're allergic or have a digestive condition.

The best solution is to choose the healthiest types of red meat: the ones that are organic, grass-fed and devoid of any chemicals or additives. Eat these in moderation, along with a balance of vegetables, fruits, nuts and lean proteins like chicken or seafood, to get all essential nutrients.