Although we can eat pretty much anything in order to survive, and we live as omnivores, Dr. Milton Mills challenges this notion and argues that we are truly designed to eat plant foods.
He has a varied experience, specialising in internal medicine, HIV disease and the relationship between nutrition and chronic disease. He has observed that those HIV patient shifting towards a more plant based diets improved with increased energy and higher T-cell counts. I met with him last October (2017) at the VegFest in London, where he presented his signature talk; “Are we humans designed to eat meat?”. Dr. Mills stayed afterwards to chat with the public and answer any question we might have. He was very patient, approachable and kind. He said he is working on a book about the subject.
The following is only a small brief of his talk. See below full length video of a similar conference, for those who may be interested in further details.
As Dr. Mills mentioned in his talk, carnivores‘ jaw and teeth are designed to cut through, tear apart and move only up and down. They don’t have enzymes in their saliva, and they don’t chew the food, they just swallow it. Their canine teeth are big and their molars past each other in a cutting motion, so they can bite through the hard skin of their preys and break apart the flesh. Their biting force is also big (dogs 300psi*, wolfs 500psi, jaguars 700psi, lions & tigers 800-900psi, hienas 1000psi). Our jaw and teeth are design to chew and can move sideways. We have enzymes in our saliva that break down only carbohydrates. Our molars come in contact with each other and move sideways in order to chew food, mix it with the saliva to start digestion. Our canines teeth are small and our maximum biting force is no higher than 150psi. We may be able to crack open some nuts but we definitely cannot cut through animals hard skin.
Carnivores have a very large stomach with high acidity*. They can eat up to 30% of their body weight in a single meal. As they only hunt every 7-10 days, their big stomach capacity is necessary to ensure their survival. The acidity in their stomach is below 1. This allows them to digest meat easily and dissolve pretty much anything they swallow including bones. Our stomach on the other hand is small and the acidity is not as high. It can hold up about 800-1200 calories in one meal, based on calorie content in foods (less than our daily caloric needs). So, we are designed to eat in batches, like we normally do, 2 or 3 times a day. The acidity of our stomach is about 4-5 with food, not very efficient in comparison when it comes to digesting meat. Herbivores in general also have a small stomach with a similar pH to ours, and are designed to eat in batches too.
The small intestine of carnivores is very short, only about 3-4 times their body length. The main enzymes being protein and fat digesting enzymes. The colon is also very short, straight and non pouched with the only function of elimination. Lack of fibre in their diet means that bacteria in the colon can only use protein residues as energy substrate. Therefore, the faecal content has to be eliminated quickly, as meat residues putrefy releasing toxic metabolites. Humans small intestine on the other hand is very long averaging 25-35 feet. It’s about 10-11 times our body length (measured head to tail). The total surface area equals the size of a single tennis court. Enzymes are a mixture of carbohydrate, protein and fat digesting enzymes. The colon is also really long, pouched and has an appendix. The main functions of the colon are water absorption, fibre fermentation, production of short chain fatty acids and vitamins, and elimination. Food spends most of its time here, more than in the stomach and the small intestine combined together (a healthy gastrointestinal (GI) tract transit of food should takes 2-4 hours to leave the stomach, 4-8 hours to pass through the small intestine, and 12 to 24 hours to remain in the colon before is eventually excreted). Thus, our digestive system is design to quickly and efficiently extract most of the nutrients in the small intestine. Then, allow an extended period of time for the fibre fermentation in the colon. Fibre fermentation is essential for an adequate physiology, optimal health, brain function and protection. Low fibre diets lead to a number of health problems and diseases. Herbivores have a very similar intestine, colon structure and functions to ours.
*The pH of a substance is measured from 1-14. Acidity is from 1 to 7, and alkalinity from 7 to 14, 7 being neutral. In acidity figures the lower the number the higher the acid content. In alkalinity the higher the number the more alkaline the substance is.
*PSI is a pressure measurement expressed in “Pound-force per Square Inch”.