By Hidaya Aliouche, B.Sc. Reviewed by Emily Henderson, B.Sc.
Meat provides protein as well as several micronutrients such as iron, and B complex vitamins. There are typically more negative health effects associated with eating meat. However, moderate consumption in well-varied and complete diets is associated with positive health outcomes.
Overall, red meat contains quality protein and essential nutrients that support a healthful diet. Moreover, the contribution of red meat towards saturated fat intake is viewed as misunderstood, and there is evidence to support the inclusion of lean red meat in diets for cardiovascular health.
Red meat as a source of essential nutrients
Dietary iron is found in two forms: heme and nonheme iron. The heme content of red meat is 10-fold greater compared to white meat such as chicken. Hemoglobin and myoglobin iron is most abundant in the ferric form of iron; this has the strongest oxidative properties but is better absorbed than non-heme iron present in plant-derived foods. Heme iron is associated with cognitive development and functioning in children and young adults.
Meat-derived, alongside animal-derived foods, such as dairy products and fish, are the sole natural sources of vitamin B12. In individuals who exclude such foods, these foods from their diet are at risk of inadequate intake. Alongside B12, dietary iron is predominantly found and has the greatest bioavailability in animal products.
Red meat provides 91% of the recommended daily intake (RDI) of vitamin B12 from the recommended daily intake of a cooked serving of 85g. Vitamin B12 reduces the risk of developing megaloblastic anemia and its deficiency is associated with irreversible neurologic disease.
Red meat also contains zinc (45–62% (males–females)) which is important in cell growth and replication, the production of bone, and fortification of the immune system. This serving also provides 52% for selenium, 21% for phosphorous, 31–36% for niacin, 31% for vitamin B6, 27–12% for iron, and 13–15% for riboflavin. As such, red meat represents a major source of essential vitamins and minerals.
The satiating effects of meat
Lean red meat is widely considered a pragmatic component of diets designed for weight loss as it has a high satiating effect. This is attributed to the satiating property of protein and the effect of protein on thermogenesis, body composition, and decrease in energy efficiency.
The controversial association of red meat intake and cancer
The World Cancer Research Fund/American Institute for Cancer Research Project stated that there was convincing evidence of a causal relationship between red meat and processed meat consumption and colorectal cancer, which has caused controversy. While established, the association may be a result of confounding alternate explanations or bias. Despite this, the association between meat intake and cancer risk has been comprehensively studied and conclusively linked.
While consumption of red meat is related to an increase in saturated fatty acids (SFAs) consumption, there are some benefits to a controlled intake of red meat. When ingested in limited quantities, health benefits can be gained; lean red meat is also considered to be a high-quality source of protein and essential nutrients.
Red meat and cardiovascular health
Studies have shown that there is an inconsistent association between SFAs and heart disease. Moreover, the methods that evaluate evidence and the reliance on types of evidence have been called into question.
When considered as a whole, studies reflect that red meat is not a unique contributor to total SFA intake and it is more likely that other dietary risk factors play a more significant role. The relationship between SFAs and heart disease depends on what it being compared to. While replacing SFAs with Monounsaturated Fatty Acids (MUFAs) and polyunsaturated fatty acids (PUFAs) is beneficial, increasing intake of other dietary components such as refined carbohydrates may increase risk.
In studies of low-fat diets optimized for healthy hearts, lean red meat has been shown to lower total cholesterol and LDL cholesterol to the same degree as white meat. With regards to other cardiovascular effects, randomized clinical trial evidence has supported that red meat, not beef specifically, results in hypertensive effects, and may even improve blood pressure and vascular reactivity.
Protein and healthy body weight and body composition
The amino acids that form the proteins in meat are considered to be essential building blocks; they are essential during growth and development early in life as well as throughout life in the repair and maintenance of tissue. Red meat is an efficient source of protein with 50% of the daily value for protein derived from 85g of cooked serving (8% of total calorie intake).
High-quality protein has been shown, in an expanding area of research, to promote weight loss and or prevent weight gain or regain in adults. In addition, it has been shown to reduce fat mass and protect against losses in lean body mass.
The protein content of meat extends further than the prevention of protein deficiency. While the recommended macronutrient intake as a percentage of total energy intake, is between 10–35% of energy for protein in adults, higher intake is associated with greater health outcomes. This includes reducing the risk for chronic diseases such as obesity, cardiovascular disease, type 2 diabetes, and osteoporosis.
The association of lean red meat intake and weight loss
With regards to diets designed for weight loss, diets that incorporate higher amounts of protein are more effective compared to standard protein, higher carbohydrate diets. Approximately 1.2 and 1.6g of protein/kg body mass/day (for females and males respectively) is essential for weight management.
Higher protein diets with increased meat consumption are also associated with greater overall satisfaction and or motivation compared to low protein diets. Due to this, the inclusion of lean red meat as a means to increase protein intake is therefore expected to increase compliance in these higher-protein diets.
Increased protein intake may lead to weight loss through several mechanisms. One key factor is improvement in appetite control which may consequently reduce food consumption. Dietary protein has a greater satiety index compared to carbohydrate or fat. Protein is also associated with increases in thermogenesis; this alters substrate oxidation, and may, in turn, influence appetite signals that control food intake.
Red meat and vitality
Aging adults, who often suffer from sarcopenia (degenerative loss of skeletal muscle mass) and the replacement of lost skeletal muscle with fat (sarcopenic obesity), benefit from the ingestion of high-quality protein and bioavailable iron derived from red meat.
Protein is associated with the increase of fat-free mass as a result of stimulating muscle protein anabolism. Branched-chain amino acids which include leucine, isoleucine, and valine are essential for protein synthesis.
Branched-chain amino acids are higher in animal proteins compared to plant proteins, with the highest concentration found in red meat. Studies have shown that soy protein has a reduced ability to stimulate protein synthesis both at rest and after post-resistant exercise compared to whey protein isolates in elderly men.
Moreover, resistance training combined with lean red meat consumption in elderly women has been shown to increase total lean body tissue mass, lean leg tissue mass, and muscle strength as compared to a controlled diet combined with similar resistance training.
source: news-medical.net
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