During the farewell service and throughout the burial ceremony of former President Daniel arap Moi last week, something caught the attention of Kenyans: “Mzee liked his meat,” his son Gideon said.
Bearing in mind Moi’s exemplary posture and lifespan, and what we have heard from various sources — that Mzee strictly observed his diet, didn’t take much meat and preferred boiled maize and yams — a question begs for an answer: Is meat really bad for us?
To answer that question, we first need to appreciate that the consumption of meat in rising throughout the world and that it will keep on increasing in the next decades.
Historically, our forefathers, who were hunters and gatherers, relied heavily on meat as food before domestication of crops, which then took over as the primary source of food as they were cheaper and required shorter periods between planting and harvesting. Animals take longer to mature for slaughter, even though biotechnology is developing quick-maturing animals, especially chicken.
As our average income increases, the amount of meat we consume per capita is following suit. Until recently, the amount of meat in our diet was viewed as a measure of status.
Several reasons explain why meat consumption has been increasing throughout civilisation. They include its palatable, high satiety value and richness in proteins, vitamins and minerals. Meat is also an important source of some micronutrients, such as iron, selenium, vitamins A, B12 and Folic acid. These micronutrients are either not present in plant-derived food or have a poor bioavailability.
In particular, high protein content for body building has been the selling point of meat. For a long time, meat has been considered the sole source of protein, the body building blocks, until scientific studies began linking to health conditions such as being overweight, heart diseases, high blood pressure and cancer.
As a nutrient source, meat is distinguished as the best source of protein for our bodies compared to all other foods. Raw red meat contains around 20 to 25g of protein per 100g. So, for every kilogramme of meat there is 200 to 250g, or a quarter kilogramme, of protein. Cooked red meat, on the other hand, contains 28 to 36g per 100g. This is because the water content decreases and nutrients become more concentrated during cooking.
Meat protein is highly digestible, at around 94 per cent compared to the digestibility of 78 per cent in beans and 86 per cent in whole wheat protein. The Protein Digestibility Corrected Amino Acid Score (PDCAAS) is a method of evaluating protein quality, with a maximum possible score of 1. Animal meats like beef have a score of approximately 0.9, compared to values of 0.5 to 0.7 for most plant foods such as beans.
The other key reason meat protein is valued is its bioavailability, which refers to what happens when you consume food and its nutrients are absorbed into the blood stream and transported to the target tissues for the necessary functions. Other foods such as beans, even if rich in protein, do not have the same bioavailability as that of meat. That means you might consume a lot of protein-rich food, but the amount of protein absorbed and used by the body is low. As such, the body does not accrue the optimum benefits from those other proteins.
Meat proteins are also recognised for having complete essential amino acids content, and amino acids are the building blocks of protein. There are 190 known amino acids, but only 20 are necessary to synthesise proteins. Within these 20, eight cannot be produced by the body. Since the body cannot make them, they are known as essential amino acids; they have to be consumed in the diet, and meat contains all essential amino acids. The other amino acids that the body can manufacture are called non-essential amino acids, and even if these can be produced by the body, it is mandatory to have all the raw materials necessary for their production. Inadequate consumption of amino acids, the primary units of proteins, can lead to protein malnutrition.
Meat is usually marketed as fresh — immediately after slaughter — or processed. Processed meat refers to that which has been transformed through salting, curing, fermentation, smoking, or other processes to enhance flavour or improve preservation. Frozen meat is not considered processed, provided no changes have taken place except packaging.
Most processed meats contain pork or beef, but might also contain other red meats, poultry, or meat byproducts such as blood. Processed meat can also be defined by having undergone at least one further processing or preparation step such as grinding, adding an ingredient or cooking, which changes the appearance, texture or taste. Processed meats also include the ready-to-cook offers of sausages mildly cured through the addition of sodium nitrite, an ingredient that imparts a characteristic pink colour and distinct taste. This variety is the enemy to human health.
In the last few decades heart diseases and being overweight have been linked with meat consumption, especially because of the fat and cholesterol in meat. However, this view has been challenged again and again because dietary cholesterol does not always translate into cholesterol in the body.
The other observation in countries such as Kenya and Tanzania is that the rural Maasai eat a lot of meat, yet show no signs of heart diseases or being overweight. When researchers discovered the low incidence of obesity and heart diseases among the Maasai, they embarked on in-depth studies to establish the basis. Between 1960 and 1980 there were several publications unravelling what they called the Maasai paradox. All these studies narrowed down to key things that Maasai do that other communities don’t.
The Maasai eat unprocessed meat, and that meat is from grass-fed animals rather concentrate-fed animals. Maasais are also physically active, burning calories equivalent to walking an average of 19m per day. Their exercise is more than enough to burn all calories gained through eating meat.
In addition, they prepare their meat by adding some herbs that have been found to have the healthy benefits of neutralising the fat effects on the body. As if that is not enough, they consume a high-meat-low-carbohydrate diet compared to the urbanites’ high-meat-high-carbohydrate diet. Such Maasai diet and lifestyle does not lead to weight complications or heart diseases.
So, when did meat become bad? One of the main problem areas in meat is processing. High-temperature cooking or processing, such as barbecuing, which is loosely referred to here as roasting, can generate compounds in food that may increase cancer risk.
These compounds are called heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons, and are produced during high-temperature or on open flame cooking of meat, especially grilling, pan-frying and barbecuing for a long period. Various scientific studies have evaluated meat preparation methods and showed associations between recurrence of multiple colorectal cancers and well- or very well-done meat consumption.
The other main characteristics of processed meat such as ham, bacon and sausages is stable pink-red colour, which is brought about by addition of preservative compounds, including potassium nitrite (E249), sodium nitrite (E250), sodium nitrate (E251) and potassium nitrate (E252). These are food additives approved in many countries, and in fact the ‘E’ in each of the codes stands for Europe, indicating that European Union has approved these additives.
However, the usage of these Dietary N-Nitroso Compounds should not exceed 200 ppm as they are mutagenic and potent carcinogenic agents in animals. Then, you may ask, why are they used yet they are known to be carcinogenic. The answer is simple: they are used since they kill a bacteria — clostridium botulinum — that produces a very dangerous toxin called botulin.
Going by the above, then, there is no cause for alarm as meat can be consumed safely by observing a few cautions. For example, the formation of HCAs that develop during high temperature processing can be significantly reduced by inexpensive and practical measures like avoidance of exposure of meat surfaces to flames, usage of aluminium foil to wrap meat before oven roasting or barbecuing, and the employment of microwave cooking, or boiling. If you have to prepare barbecue meat, avoid instances that will lead to dripping of fat that cause flames to flare, such as poking with a fork.
RED VS WHITE
In conventional terminology, meat is conventionally classified as “red” when characterised by a typical red hue, whereas “white” usually defines lighter-coloured meat types.
Although a semantic debate is still open, the red type defines the meat of most adult mammals like cows, sheep and goats, whereas white meat is typically used to identify poultry, fish and rabbit.
Based on the colour, white meat is considered to be healthier than red. White meat is also not associated with cancer risks. In fact, high intake of fish brings a significant protection.
One of the main differences between red and white meat is what is called heme molecule in meat myoglobin, which is present in red meat in high concentrations. Poultry and fish have tenfold lower amounts of heme molecule. It has been shown that high amounts of heme iron promote development of colon cancer.
WHAT TO AVOID
Avoid processed meat, particularly varieties with very stable pink-red colours such as bacon, ham and sausages. This is because these have additives considered to be potential carcinogens, particularly if the limits are not strictly adhered to.
Various countries have released advisories for their populations to minimise processed meat, and if they have to consume red meat to limit it to 500g per week, or approximately 70g per day.
Many countries and organisations have also issued various guidelines on processed meats:
In the US: The 2015—2020 Dietary Guidelines recommend limiting red meat intake, including processed meat, to approximately one weekly serving.
In the UK: The UK’s dietary guidelines endorse limiting the intake of both red and processed meat to 70g per day.
Researchers: The World Cancer Research Fund and the American Institute for Cancer Research recommend limiting red meat consumption to moderate amounts and consuming very little processed meat.
WHO: World Health Organisation’s International Agency for Research on Cancer has indicated that consumption of red meat is “probably carcinogenic” to humans, whereas processed meat is considered “carcinogenic” to humans.
Dr Arimi is a senior lecturer in Food Science at Meru University of Science and Technology.