(THE STAR/ASIA NEWS NETWORK) - My sons and their girlfriends recently came to stay at our place in France. The girls are genuinely nice people and one of them is strictly vegetarian. As someone with always a few slabs of emergency steak in the freezer, vegetarianism posed a few logistical issues during mealtimes, but nothing we could not manage, especially as she conjured up a delicious vegetarian dinner for everyone one evening.

It did, however, provoke an interest in what happens when people diligently decline to eat meat (I had not met a single vegetarian in France before). Research highlighted interesting findings, which may also help non-vegetarians like me.

So this series of articles - in five parts - is not only about vegetarianism, it is also a review of human dietary tracts, along with biochemical, industrial and ecological factors that affect our food and well-being in the modern world.

The Fake News

But first, let us debunk a few common fallacies that swirl around the media. One common fallacy is that humans are by nature not meat eaters - it is claimed that we do not have the jaw and teeth structure of carnivores.

It is true that humans are not designed to eat raw meat, but that is because our jaws have evolved to eat cooked meat, which is considerably softer and much easier to chew.

And there is evidence that humans have been cooking meat for at least 450,000 years, probably even longer - a sign is the overbite in human teeth (our upper teeth are slightly in front of our lower teeth in the jaw), which indicates the preponderance of soft cooked meats in the diet.

True carnivores need much stronger jaws, perfectly aligned teeth and big cutting incisors precisely because they cannot cook meat and must therefore cut and chew tough, raw flesh with their teeth.

They also spend a much longer time chewing and eating to obtain the same calories from their food.

Another fallacy is that meat is somehow acidic and difficult to process through the long human intestinal system. In fact, the pre-digestion of food in the acidic cavity of the stomach results in a lumpy mush called chyme - this acidic chyme is then treated by pancreatic juices as it passes through the duodenum.

The strong bicarbonate ions in the pancreatic juices render the chyme alkaline as it enters the intestines - and the reason is because digestive enzymes in the small intestines work better in a mildly alkaline environment.

Yet, another common piece of misinformation is that humans are not really designed to digest meat in any case - and this is the reason for many dietary disorders.

However, humans produce several pancreatic enzymes specifically to digest fats and proteins, such as pepsin, trypsin, chymotrypsin and lipase.

Perhaps the most telling indicator is probably human bile, which contains salts such as bilirubin and biliverdin, which break down and emulsify animal fats so that the pancreatic enzymes can process chyme more efficiently. The composition of human bile is therefore significantly different from the bile of animals that eat only greens, such as ruminants.

What is more true is that during most of human evolution, the supply of meat was variable - it would have been extremely unlikely that Palaeolithic man ate meat (or ate at all) every day whereas it is now possible for ordinary people to have substantial amounts of fresh meat every day and for every meal as well, if they so desired.

This has been true for only less than a century due to modern production, refrigeration and transport logistics. Whether this possible over-consumption of meat is a significant factor for various modern dietary-induced issues will be discussed later.

There are other dubious claims about meat consumption - for example, meat has been blamed for the increase of human allergies.

The fact is that 90 per cent of all human allergies can be traced to just seven foods: milk, eggs, nuts, fish, shellfish, wheat and soya bean products - none of these is an animal-based meat.

An allergic reaction to pork, lamb or beef is quite rare, unless humans have been bitten by certain insects such as the Lone Star tick (or possibly the Castor Bean tick), in which case the huge overproduction of an antibody called immunoglobulin E (or IgE) caused by the bite can render humans allergic to mammalian meat - the antibody IgE is basically the human body's defence against an alien carbohydrate called alpha-gal generally found in most mammalian flesh, apart from primates.

How this allergy to meat is induced by an insect is fascinating - nobody really knows, though there are several theories undergoing validation.

Meat has also been blamed for causing other diseases, especially as processed meats had been classified in late 2015 as a Group 1 carcinogen by the World Health Organisation, citing an 18 per cent increased risk of bowel cancer.

This sounds dramatic, but in the context of an overall incidence rate of 6 per cent for bowel cancer (in the United Kingdom), an 18 per cent increase of risk raises that overall risk up from 6 to 7 per cent.

As for meat causing other diseases, most common serious allergies are not caused by eating meat, as mentioned earlier. If meat is a consistent disease-causing agent, one would have expected many more allergies and reactions among the general population.

Meat Isn't Always Necessary

On the other hand, despite what the meat industry may say about the importance of proteins, there is no requirement for the superfluous consumption of animal proteins, especially by adults.

Many plant-based foods such as soya, oats, peanuts, lentils, squash, courgettes and kale, are excellent alternate sources of protein. It is practically impossible to suffer protein deficiency if a varied vegetarian diet is followed.

However, there may be some slight issues with totally excluding animal proteins - more on this later.

Omnivores

So, no matter what has been said, all the evidence points clearly to humans being omnivores, who are capable of eating and digesting animal and plant foods efficiently. And this was clearly a huge evolutionary advantage for humans as it opened up a much wider supply of food.

Cooking and agriculture, including meat farming, were the two major foundation developments that allowed humans to become the dominant species on our planet. Explanation can be found at www.thestar.com.my/lifestyle/food/features/2014/05/11/what-you-probably….

The Real Research

It has often been claimed - and there is credible evidence to support the claim - that vegetarianism generally leads to better longevity and a lower incidence of coronary heart disease (CHD) and cancers in humans.

Perhaps the most relevant study is an American investigation published as the Vegetarian Dietary Patterns And Mortality In Adventist Health Study 2 (also known as AHS-2), in which the dietary habits of 73,308 participants (all US-based Seventh Day Adventists) were studied in depth, even breaking down diets into categories such as non-vegetarian (general meat eaters), semi-vegetarian, pesco-vegetarian, lacto-ovo vegetarian and vegan.

For the purposes of this study, a semi-vegetarian is someone who consumes meat and fish once a week; a pesco-vegetarian is a fish-eater, but who can also eat meat once a month; a lacto-ovo vegetarian eats eggs and dairy, but restricts consumption of fish and meat to once a month; and vegans are those who eat eggs, dairy, fish and meat only up to once a month.

Without dabbling into the detailed statistics, one of the major overall conclusions was that mortality was found to be 12 per cent lower for subjects who are not general meat-eaters - statistically speaking, this is a big deal.

Interestingly, the study also found that the incidence of strokes was higher for female subjects who were not meat-eaters, though this item was not originally presented as a research outcome.

Also, there was no hugely conclusive evidence that incidence of cancers was altered by diets, though it seems that female vegetarians have a lower risk of female-specific and gastrointestinal cancers.

However, the AHS-2 findings contrasted with another comprehensive study done in the UK: the European Prospective Investigation into Cancer and Nutrition-Oxford University (EPIC-Oxford) called Mortality In Vegetarians And Comparable Non-vegetarians In The United Kingdom, covering 60,310 subjects.

The categories are different too, being more simply divided into regular meat eaters, low meat eaters, fish eaters and vegetarians, including vegans.

In the EPIC-Oxford study, no statistically significant differences were found in the overall mortality rates for all categories, though there was some concurrence with AHS-2 in terms of lower death rates from CHD for vegetarians.

Due to the significant variance in the findings between AHS-2 and EPIC-Oxford, especially regarding mortality rates, further analysis was done on the discrepancies and some probable explanations for the differences between AHS-2 and EPIC-Oxford have been noted.

One is that the dietary patterns of AHS-2 and EPIC-Oxford subjects are themselves subject to wide differences; for example, the amount of fibre consumed by AHS-2 subjects averaged over 46g a day, compared with about 27g a day for the UK subjects.

The amount of vitamin C (ascorbic acid) consumed by the UK subjects was also about only half the amount consumed by the American subjects.

Other statistical elements which may skew results are the age of the research participants and how long they have maintained their dietary choices - the US Seventh Day Adventists have generally adopted healthy eating as a lifestyle choice since birth.

However, in the UK, being a vegetarian is a dietary choice that started only around 1972 before gaining mainstream popularity much later. Therefore, the UK vegetarians have not been life-long vegetarians in general.

Before the 1990s, people who did not eat meat in the UK were often considered strange, super-religious, a little ill or possibly all three.

Another factor may be the lifestyle choices of meat eaters, who may consume more unhealthy fried foods or perhaps also indulge in tobacco and/or alcohol as they would be less restricted by a desire for healthy foods - meat eaters in the US also eat significantly more meat than other countries.

As an aside, vegetarians were known as Pythagoreans until the mid-19th century - this name was derived from the famous sixth-century Greek mathematician, who was probably one of the earliest ethical vegetarians.

Oddly, people who were strictly Pythagoreans were also forbidden to eat beans and Pythagoras was allegedly killed when he refused to escape from his enemies by walking across and damaging a bean field.

Till today, no one knows why he was so extraordinarily considerate to beans.

There is now a constant barrage of blogs, glossy magazines and fanciful articles on the pros and cons of vegetarianism - much of it is rather biased towards the pros which, on closer inspection, also do not amount to much more than fads, anecdotes and opinions, such as the various "clean eating" movements.

One recent odd item of research indicated that the type of vegetarian diet can also affect human health, particularly CHD.

It seems that ingesting lots of "unhealthful" plant foods such as refined grains, sugary (plant-based) drinks and fries can be bad for health compared with eating unprocessed fibre-rich vegetables, less sugar and foods which are not deep-fried in oil. If you are now thinking that news about this subject has gone silly, then I have to agree.

However, the large-scale research results are overall reasonably compelling, especially when applied to diseases such as CHD.

Additionally, it is important to stress that research definitions of the vegetarian (or "non-meat eating") categories did not mean a total abstinence of meat, dairy or fish, even though true vegans are also included in these categories.