Humans are omnivores, meaning we consume both plant and animal matter. While vegetarian and vegan diets are possible, there are good reasons why most people choose to include at least some meat and animal products in their diets. Meat provides essential nutrients that are difficult or impossible to get from plant sources alone. Additionally, our evolutionary history and bodies provide evidence that humans are well-adapted to eating meat. With a balanced diet including lean meats and plenty of vegetables, meat can be part of a healthy lifestyle.
Key Nutrients in Meat
Meat contains all 9 of the essential amino acids our bodies require but cannot synthesize on their own. While plant proteins can provide these if combinations of foods are eaten to complement amino acid profiles, meat contains all essential amino acids in each bite. Meat proteins are well-absorbed and utilized by the body.
Meat is an excellent source of micronutrients like iron, zinc, and vitamin B12. Iron supports the transport of oxygen in the blood and supports immune, cognitive and energetic functions. Zinc supports immune function, DNA synthesis, and growth. Vitamin B12 maintains nerve and blood health and supports DNA synthesis.
These nutrients are very low or completely absent from plant foods. Iron and zinc from plants have reduced bioavailability. Vitamin B12 is only found naturally in animal foods. Vegans must supplement B12 through fortified foods or pills.
| Nutrient | Main Functions | Top Food Sources |
|---|---|---|
| Iron | Transports oxygen, supports immunity and energy | Red meat, poultry, seafood |
| Zinc | Immunity, growth, DNA synthesis | Red meat, poultry, seafood |
| Vitamin B12 | Nerve health, red blood cell synthesis | Animal foods only |
Evidence From Human Evolution
Evidence from fossil records indicates early human ancestors may have eaten meat as early as 2.6 million years ago. Changes in digestive anatomy, dentition, and the use of tools for hunting provide evidence of regular meat consumption by at least 1.5 million years ago.
The high calorie and nutrient density of meat supported the evolution of larger, energy-hungry human brains compared to other primates. Cooking meat further increased digestion and nutrient absorption. Overall, anthropological evidence indicates meat-eating has evolutionarily shaped modern human bodies and metabolism.
Body Composition and Muscle Mass
Diets with higher protein, including from meat, support increased muscle mass and physical performance compared to lower protein vegetarian diets. Muscle mass tends to decrease with age, increasing risk of frailty and falls. Higher protein intake, combined with exercise, helps maintain muscle and strength in older adults.
Meat contains the complete proteins and micronutrients needed to support growth and maintenance of lean muscle mass at all life stages. Vegetarians, especially vegans, should pay special attention to eating a variety of complementary plant proteins and sufficient calories to meet needs.
Brain Health
Meat is rich in iron, zinc, B12, and other brain-supporting nutrients. Deficiencies in these nutrients are linked to increased risk for brain fog, memory problems, stroke, depression, and dementia.
Red meat provides vitamin B12 needed to synthesize neurotransmitters and myelin sheaths protecting nerve fibers. Zinc supports neuron development and communication. Iron carries oxygen needed for all brain functions.
Overall, moderate meat intake as part of a mixed diet supports healthy brain development, cognition, and nerve function across the lifespan. Those avoiding meat should supplement with iron, zinc, and B12.
Energy Levels
Meat provides all 9 essential amino acids needed to build energizing proteins and muscle fibers. The iron in meat helps circulate oxygen to muscles. The high quality protein boosts metabolism compared to eating just plant proteins and carbohydrates.
The B12 in meat is needed to metabolize energy from food. Low B12 can cause fatigue even when eating enough calories. The zinc in meat supports thyroid function, which manages metabolism.
For stable energy levels, meat provides the necessary nutrients to support muscle-building, oxygen circulation, metabolism, and efficient macronutrient use.
Exercise Performance
Athletes and regular exercisers have higher protein needs to optimize performance and recovery. Protein before and after workouts helps build and repair muscle fibers broken down during exercise.
Complete, high-quality animal proteins provide essential amino acids muscles need to increase size and strength in response to resistance exercise. Meat also provides readily absorbed iron to deliver oxygen to active muscles.
Multiple studies show meat-inclusive diets support increased strength and muscle mass gains from training compared to vegetarian or vegan diets. Lean meats are recommended for optimizing athletic performance and results.
Disease Prevention
Lack of iron, B12, and zinc are linked to increased risks of some cancers, heart disease, and stroke. As plant foods provide these in limited amounts with lower absorption, vegetarians and vegans have higher rates of deficiency for these nutrients.
Higher risks for cardiovascular disease, cancer, and diabetes have been observed with vegan diets compared to balanced diets including lean meats. Vegetarians and vegans should supplement with iron, zinc, and B12 to help minimize these risks.
As with all foods, proper preparation and portion sizes are key to getting health benefits from meat while minimizing disease risks associated with overconsumption.
Growth Needs in Childhood
Children have high protein needs to support growth and development. Lack of essential amino acids from meat and animal products can result in growth stunting.
Iron deficiency is also concerning for children’s neurological development. B12 is essential for brain growth and function. Zinc supports immune function, growth, and development in babies and children.
Without adequate intakes of iron, zinc, B12 and complete proteins from meat or other animal foods, children are at risk for stunted growth, impaired cognition, and increased infections.
Nutrient Absorption
Meat proteins are more digestible and bioavailable than plant proteins. Absorption of zinc, iron, and B12 from meat also exceeds that from plant sources.
Phytates in whole grains, legumes, nuts and seeds bind minerals like iron and zinc, inhibiting their absorption. Plants lack vitamin B12 entirely. Even with adequate plant intake of iron, zinc and B12, the reduced absorption increases deficiency risks.
Overall, meat provides more usable essential proteins and nutrients compared to vegetarian sources. Ovolactovegetarians can meet needs if eggs and dairy are consumed. Vegans will require supplements.
Satiety
Proteins take longer to digest, providing a prolonged feeling of fullness compared to eating carbohydrates alone. Meat is one of the most satiating proteins.
Replacing carbs with meat results in increased satiety, reducing subsequent calorie intake. This can assist with managing hunger and weight control.
Nutritional Drawbacks
While meat provides beneficial nutrients, there are some nutritional drawbacks to consider:
- Saturated fats and cholesterol when eating fatty cuts of meat can increase cholesterol levels and heart disease risk if consumed in excess.
- Carcinogens form in meat during high-temperature cooking like grilling and frying. Consuming charred, overcooked meat regularly may increase cancer risk.
- Processed meats like bacon and sausage contain added sodium and nitrates/nitrites that have been linked to increased risks of chronic diseases.
Choosing leaner cuts of meat and preparing them in healthier ways can help minimize these risks.
Environmental Considerations
Modern mass production of meat for human consumption raises environmental concerns:
- Methane emissions from livestock contribute significantly to greenhouse gas emissions linked to climate change.
- Clearing forests and growing livestock feed requires land and water resources, loss of biodiversity.
- Animal wastes pollute air and waterways if not properly managed.
However, well-managed grazing livestock can be neutral or even beneficial for soil health and carbon sequestration. Overall, reducing meat consumption and choosing sustainably raised animal products can help minimize environmental impacts.
Ethical Considerations
Ethical objections to eating meat focus mainly on animal suffering. Concerns include:
- Inhumane conditions in factory farms and industrial slaughterhouses.
- Stress and health impacts of confined, high density housing.
- Physical alterations like dehorning without pain medication.
- Using animals solely as means to human ends versus respecting their intrinsic value.
These objections can be addressed by purchasing meat from suppliers using higher-welfare practices. Other options are wild game or carcass meat where the animal lived freely. Some argue ethical meat-eating is possible.
Conclusion
Humans evolved eating meat and animal products. Meat provides high quality proteins and essential nutrients humans require, in forms more readily absorbed compared to plant-based foods. At moderate intakes as part of a balanced diet, meat offers metabolic, muscular, neurological, energetic and nutritional benefits.
However, ethics and sustainability should also be considered. Overconsumption, low-quality meat and poor preparation increase health risks. With mindful choices, meat can positively contribute to a healthy human diet and lifestyle.
