Your Stomach Proves You're Built to Eat Meat

Greetings, Primals!

What do a human, a lion, an alligator, and a vulture all have in common?
Answer: A highly acidic stomach designed for breaking down animal protein! Most people never stop to think about how our digestive system is built — but it's one of the clearest clues to what we’re meant to eat.

In this week’s issue:

WEEKLY DEEP DIVE

Humans are hypercarnivores — just like lions, alligators, and vultures! We’re monogastric animals with stomach acid so strong it rivals that of scavengers. Our gastric pH (around 1.5) is optimized to break down animal flesh fast — turning protein into amino acids that can be rapidly absorbed in our small intestine. This setup reflects our design: short ingestion, short digestion, maximum efficiency.

According to a study published in PLoS ONE, species that regularly consume meat — especially scavengers and predators — evolved extraordinarily acidic stomachs to protect against pathogens and to digest flesh quickly. Humans fall into that same category, with a stomach pH closer to vultures than to plant-eating animals like cows or gorillas.

Now contrast that with ruminants. Cows, deer, gorillas — these plant-eaters have multi-chambered stomachs built for fermentation, not acid digestion. Their digestive strategy is slow and microbial, not fast and acidic. In the case of cows, the rumen maintains a near-neutral pH (around 6–7), creating the perfect environment for billions of bacteria to thrive.

These microbes break down cellulose — the tough, fibrous walls of plants — through fermentation, producing short-chain fatty acids (SCFAs) like butyrate, acetate, and propionate, which the animal then absorbs and uses for energy. This process can take many hours, even days.

These animals are built to extract nutrients from grass, leaves, and fibrous material — foods we simply aren’t equipped to digest efficiently. Humans don’t have a rumen! We don’t have microbial fermentation chambers or time on our side. When we eat greens, most of it passes through us with little nutrient extraction! We weren’t built for fiber fermentation — we were built for flesh absorption.

That’s why red meat is your most efficient, bioavailable food source. When you eat the animal, you absorb what it absorbed — no middleman required!

The Primal Takeaway

Our ancestors didn’t rise to the top of the food chain by accident — they got there by eating meat! The extreme acidity of the human stomach isn’t just a digestive feature; it’s an evolutionary advantage. It allowed early humans to safely consume raw meat, scavenge when necessary, and absorb dense nutrition quickly. This fueled rapid growth, physical strength, and survival in harsh environments. Our acidic, monogastric design wasn’t made for greens — it evolved out of necessity!

With Gratitude,

Will Winston, PHC

“Our results always match our choices. Therefore choose to Keep It Primal!”

Beasley et al., 2015 – "The Evolution of Stomach Acidity and Its Relevance to the Human Microbiome"]

Bergman, E.N. (1990). “Energy contributions of volatile fatty acids from the gastrointestinal tract in various species.” Physiological Reviews, 70(2), 567–590