Long-term observational studies of heart disease, cancer or death, as well as controlled trials of risk factors such as blood cholesterol, glucose and inflammation, suggest that moderate intake of unprocessed red meat is relatively harmless to health. However, there are no major studies showing any benefit to eating it.

So eating a little steak, lamb, or pork once in a while may not make your health worse, but it won’t improve it either. Also, too much heme iron can give red meat its red color, which may explain why red meat increases the risk of type 2 diabetes. Regular consumption of red meat, and even occasional processed meat, is also strongly associated with colorectal cancer.

You should prefer lean meat

For decades, dietary guidelines have focused on lean meats because they are lower in fat, saturated fat, and cholesterol. But these nutrients are not strongly associated with heart disease, cancer or other major health problems.

Other factors seem to be more important. Processed meats, such as bacon, sausage, salami, and cold cuts, contain high amounts of preservatives. For example, sodium increases blood pressure and the risk of stroke, while the body converts nitrite into cancer-causing nitrosamines. Thin or not, these products are not healthy.

Focus on a “plant-based” diet

“Plant-based” has quickly become synonymous with “health,” but that claim is somewhat misleading. First, not all animal foods are harmful. Poultry and eggs appear to be relatively neutral. Dairy products may have metabolic benefits, especially for reducing body fat and type 2 diabetes. Also, seafood has several health benefits.

Instead, many of the worst foods are plant-based. Examples include white rice, white bread, fried foods, fine breakfast cereals, cookies, and more. These foods are high in refined starches and sugars and make up 42 percent of total U.S. calories. By comparison, unprocessed red meat makes up about 5 percent of U.S. calories, and processed meat makes up about 3 percent.

Either a “plant-based” diet or an omnivorous diet can be unhealthy. It depends on what you choose to eat.

Grass-fed beef is good for your health

Traditional livestock feed (grass, other greens, legumes) plus hay plus corn, soybeans, barley or grains. Livestock that are “grass-fed” or “grass-fed” eat primarily, but not exclusively, forage. In theory, “grass-fed” livestock should only eat grass. But no body regulates the industry’s use of these terms. “Free range” describes where the animals live, not what they eat.

“Grass-fed” may sound better, but there are no studies comparing the health effects of eating grass-fed and conventional beef. Nutritional analyses showed little difference between grass-fed and conventionally raised livestock. You may be eating grass-fed beef for personal, environmental or philosophical reasons. But don’t expect it to be good for your health.

Plant-Based Meat Alternatives Are Healthier

Products like the Impossible Burger and Beyond Meat are clearly more environmentally friendly than conventionally raised beef, but their health effects remain uncertain. By design, most nutrients in plant-based alternatives are similar to meat. With genetically engineered yeast, it’s not even possible to add heme iron. These products also contain large amounts of salt. And, like many other ultra-processed foods, they may lead to higher calorie intake and weight gain.

So what are the facts?

Processed meat is bad for your health

Processed meats contain problematic preservatives. Even those foods with “no added nitrates or nitrites” on the label contain nitrite-rich fermented celery powder. A recent petition from the Center for Science in the Public Interest asked the FDA to ban the misleading label.

In addition to sodium, nitrite, and heme, processed meats may contain other carcinogens that are produced by charring, smoking, high-temperature frying, or grilling. These compounds may not only harm the person who eats these products; they can also cross the placenta and harm the fetus.

Meat-free diets are not inherently healthy

Most diet-related illnesses are caused by too few health-promoting foods such as fruits, nuts, seeds, legumes, vegetables, whole grains, vegetable oils, seafood, and yogurt. Additional health concerns come from too much soda and ultra-processed foods high in salt, refined starches or added sugar. Compared to these major factors, avoiding or occasionally consuming unprocessed red meat itself has little effect on health.

Beef production is destroying the environment

Unprocessed red meat production has about five times the environmental impact of fish, dairy or poultry in terms of land use, water use, water pollution and greenhouse gas emissions. This effect is about 20 times greater than that of eggs, nuts or beans, and 45 to 75 times greater than that of fruits, vegetables or whole grains. A 2013 UN report concluded that livestock production is responsible for about 15 percent of global greenhouse gas emissions, nearly half of which comes from beef.

Plant-based meat is better for the environment

Compared to conventional beef, the production of plant-based meat substitutes consumes half the energy, one tenth the land and water, and reduces greenhouse gas emissions by 90 percent. However, no studies have yet compared plant-based meat substitutes with more natural, less processed alternatives, such as mushrooms or tofu.

There are still many questions

Which preservatives or other toxins in processed meat are most harmful to humans? Can we eliminate them? What exactly increases the risk of type 2 diabetes in unprocessed red meat? What innovations can reduce the huge environmental impact of meat (even grass-fed beef)? What are the health effects of grass-fed beef and plant-based meat alternatives?

Like a lot of scientific research, the truth about meat is subtle. Current evidence suggests that people should not consume unprocessed red meat more than once or twice a week. Grass-fed beef may be slightly better for the environment than traditional production methods, but it is still very harmful to the environment. The data do not support major health differences between grass-fed and conventional beef.

Likewise, plant-based meat alternatives are better for the planet, but not necessarily better for our health. Fruits, nuts, legumes, vegetables, vegetable oils and whole grains remain the best choices for human and planetary health.