MEATing the protein requirements, but at what STEAKS?
- Dr. Sadiya Khan, Intern, Bangalore.
- Anagha A, 4th Year Medical Student, Osmania Medical College.
Protein is the essential macronutrient comprising 10-15% of the balanced diet and meat is a major source of protein for humans. The National Academy of Medicine recommends a minimum daily intake of 0.8g protein per kg body weight per day for adults. Meat contributes to a large chunk of the diet in middle and low income countries due to its numerous benefits. It is a complete protein that contains all 9 essential amino acids and is a rich source of vitamin B12, riboflavin, niacin, iron, zinc and selenium.
Meat is broadly divided into 2 categories – red and white. Red meat refers to all mammalian meat which are red in colour when raw. They contain higher amounts of fat, vitamins, iron and zinc. The presence of high levels of myoglobin-an iron based protein is responsible for the colour. Red meat includes 5 different types of mammals’ meat –
1. PORK – pigs flesh is the most affordable and widely used meat globally, with a high protein content of 13.3g, vitamin B, zinc and selenium. It is also a good source of omega
3 fatty acids. However the high fat content poses a cardiovascular risk on excessive consumption.
2. BEEF – Cattle meat is a rich source of protein (content -17g), carnitine, niacin, oleic acid, iron, vit B12 and zinc.
3. VEAL – Calf meat is a costlier variety of meat which is pinker in colour, has a firm texture, and a total protein content of 20g. It is leaner, containing lower amounts of fat and high levels of vitamins. Veal liver is a rich source of vitamin A.
4. LAMB, HOGGET & MUTTON – All are domestic sheep’s meat – with Lamb referring to under-1-year old sheep, Hogget to 2-year-old and olders are mutton. They are a good source of protein (content -17g), omega-3 fatty acids, vitamins and help in muscle maintenance, bone health and better immunity.
5. GOAT – It is a leaner and healthier choice with low cholesterol and high protein
content of 21g.
White meat is a better source of leaner protein with less fat content and it is white in colour both before and after cooking due to the lower levels of myoglobin. Poultry and seafood falls under this variety.
1. CHICKEN – It is very affordable, easy to cook and available in various forms. It contains
20g of protein and low levels of cholesterol. The amino acid tryptophan makes it a mood enhancer.
2. TURKEY – Its nutritive value is similar to chicken with a higher protein content of 24.6g. (But it has higher levels of sodium and skin fat.)
3. DUCK – The fat content is higher compared to protein (content -11g) but it is similar to olive oil fat including the PUFAs and MUFAs making it healthier for consumption.
4. GOOSE – It is pricier and has higher levels of iron compared to other poultry meat. It has a protein content of 16g.
5. PHEASANT – It is an exotic, expensive, leaner white meat containing 24g protein, dense nutrients and fewer cholesterol and fats.
6. SEAFOOD – It comes in variety of species including fish, shellfish, clams, oysters, scallops, squids etc. They are a rich source of omega-3-fatty acids, vitamins and protein (content -19g).
There are other wild varieties of meat like venison, wild boar, rabbit etc which are leaner, flavorful and very high in protein when compared to domesticated meat.
Meat can be consumed as raw red meat in the form of cuts of unprocessed beef, pork, lamb like pork tenderloin, sirloin steak or as processed foods like hot dogs, ham, sausages, corned beef, canned meat, beef jerky etc. Methods like salting, curing, fermentation, smoking etc. are used to process meat which enhances the flavour and prolong preservation.
While raw meat consumption poses a risk of infection with bacteria and parasites, there are higher risks associated with the intake of processed foods. The chemicals used for preservation like salts, nitrates are linked to an increased risk of type 2 diabetes, cardiovascular disease, cancer and premature death. Despite the numerous benefits of meat intake, an increasing number of studies in the last decade highlight the potential adverse effects of too much meat especially red meat consumption on our bodies.
A meta-analysis of data suggested an increased risk of colorectal cancer by 18% on daily consumption of 50g portion of processed meat. Although the risk is small, this is a major point of concern for public health especially due to the increasing meat consumption in low and middle income countries. Heme and free iron present in red meat play a role in increased production of reactive oxygen species which further leads to inflammation, cytotoxic effects and genetic mutations. High temperature cooking of meat leads to release of multiple carcinogens like N-nitroso compounds, heterocyclic amines, and polycyclic aromatic hydrocarbons. Excessive red meat consumption also leads to an elevated production of uremic toxins by the gut microbiota which increases the risk of cardiovascular mortality and accelerates damage in patients with chronic kidney disease. Low protein diets especially with plant based protein sources have been found to benefit patients with chronic kidney disease.
Studies also found that people who consume large amounts of red and processed meat have nearly a 50% increased risk of Non Alcoholic Fatty Liver Disease which is becoming a serious global health burden. Meat can lead to fat deposition in the liver, triggering inflammation and causing insulin resistance; thus also increasing one’s risk of developing type 2 diabetes mellitus. The culprits are most likely the saturated fat, high sodium content and preservatives.
Now the question is; how much meat is too much? Do we have to absolutely give up our juicy steaks and crispy chicken burgers?
You do not have to go cold turkey. The AHA recommends cutting back on meat consumption, sticking to lean cuts and portions that are no larger than 6 oz; and inclusion of heart-healthy alternative sources of protein like kidney beans,soybeans, lentils etc. The World Cancer Research Fund and American Institute for Cancer Research (AICR) recommends the following measures that could be followed to maintain a healthy balance:
- a maximum consumption of 3 servings of red meat per week (equivalent to 12-18 oz) and
- Avoiding open flame, barbecuing and other methods of cooking at high temperatures
- Discarding charred portions of meat
- Pre Cooking meat in microwave and regular flipping while cooking on high flame
- Inclusion of antioxidant rich vegetables like leafy greens in the diet.
