Can Humans Eat Like Gorillas?

Dear Dr. Childers,

The other day I had a disagreement with a vegan friend of mine.  He says gorillas live on vegetation, and so can we.  I argued that we need meat to be healthy.  Who is right?

An omnivore.

Dear Omnivore,

To eat like a gorilla we should graze all day (forget holding a job) to obtain 40 lbs. of vegetation (requires a big gut) and develop the ability to digest cellulose. If your friend can digest cardboard snacks he just might begin to qualify.

Many who become vegan do not do so for health reasons, but out of compassion for animals and a disdain for modern, large-scale commercial farming practices.  I understand their concerns, and agree change is necessary (sustainable farming, e.g.), but will reserve my comments for a later post.

In terms of diet, humans are more aligned with the omnivorous chimpanzee, which, in addition to vegetation, eats termites, eggs, ants, small animals and occasionally hunts for meat. I recall hearing a report on the radio (probably NPR) that the chimp who delivers the most meat to females fathers the
most offspring. Hunter chimps are the fit whose genetics survive.

Gorillas do not worry about natural sources of B12. Humans do, and the human gut uses meat to create B12. Fortunately for vegans and some vegetarians, they cheat a little (take B12 and perhaps calcium and other supplements created in the lab).  But our success as a species is measured by our ability to survive in any climate, sans laboratory-created supplements.  Unlike his omnivore brothers, the vegan or strict vegetarian could not survive in a wilderness for long.

Strict vegetarian and vegan diets suffer from a number of other significant nutritional drawbacks.  Omega 3 fatty acids DHA and EPA are nearly absent from a vegan/strict vegetarian diet.  Vegetarians who do not eat fish tend to be deficient in these essential fatty acids.  And without red meat, iron stores are very difficult to support on these diets; most vegans/vegetarians who do not take supplements have poor iron stores.

Then there are concerns about growth and development.  Children require energy dense foods. Pound for pound they consume and expend more energy than most adults. Children on vegan diets must eat too much bulk to get the energy they need to support normal growth and development. Children need a nutrient-dense diet.  A diet that is high in bulk and indigestible fiber compromises nutrition and places them at risk, for example, to become short adults.

From evolutionary and developmental standpoints, it takes a lot of nutritional resources to develop and support a big brain. The brain is about 70% fat, and contains lots of cholesterol.  An important contributor to brain development in humans is animal fat. If vegans/vegetarians do not breast feed their infants, or otherwise fill their fat requirements, their infants may be compromised. Soy formula is not an ideal substitute, and is currently under scrutiny for its high phytoestrogen content and other potential nutritional and hormonal problems. 

Some argue there are cultures that are entirely vegetarian that do well. This is not shown to be the case. Vegetarians in India, for example, suffer from a number of nutrition-related problems.  Additionally, from a historical standpoint the ingestion of insects and grubs in the diet has been too often overlooked when native diets are documented out in the field--a Western culture blind spot. Grubs, for example, are a nutrient-dense source of "animal" fats and iron for many cultures, but are not considered "meat."
'Gives new meaning to "serving up some grub."

To make a short story long (a skill of mine), I side with you in this argument.  This said, there are many paths to a healthy human diet, from carnivorous to omnivorous.  I sincerely hope your friend finds his own path to lasting health and happiness.