Our ancient ancestors ate a dramatically different diet from what we consume today. Thanks to groundbreaking research from the University of California, San Francisco, we can now quantify precisely how different our ancestors’ diets promoted an alkaline balance in their bodies while our modern diet promotes acidity. This shift represents one of the most fundamental changes in human nutrition since we began farming 10,000 years ago.
Measuring the Change
The researchers used a measure called Net Endogenous Acid Production (NEAP) to quantify how much acid or base different diets produce in the body. A negative number indicates a base-producing (alkaline) diet, while a positive number indicates an acid-producing diet. When they analyzed 159 possible combinations of pre-agricultural diets, the results were striking:
- The average ancestral diet produced -88 mEq of acid per day (meaning it was base-producing)
- A remarkable 87% of these ancestral diet combinations (139 out of 159) were base-producing
- There was considerable variation (±82 mEq/day), but most combinations remained firmly in the base-producing territory
In contrast, the modern American diet tells a very different story. Today’s typical diet produces +48 mEq of acid per day—a number validated by real-world measurements. Researchers studying free-living Americans consistently found similar results: one study measured +49 (±18) mEq/day, while another found +43 (±19) mEq/day. This isn’t just theoretical. Historical observations of New Guinean hunter-gatherers living a traditional lifestyle found their urine pH typically ranged between 7.5 and 9.0. These remarkably alkaline values can only be achieved through a strongly base-producing diet rich in potassium bicarbonate.
Why This Dramatic Reversal Matters
The shift from -88 mEq/day (ancestral) to +48 mEq/day (modern) represents a swing of 136 mEq/day toward acid production. This reversal occurred through three major dietary changes:
- The displacement of base-rich plant foods (like tubers, fruits, and leafy greens)
- The introduction of cereal grains, which produce acid in our bodies
- The addition of modern processed foods, which are energy-dense but nutrient-poor
Our bodies must maintain blood pH within an extremely narrow range (7.35-7.45) to sustain life. When we eat acid-forming foods, our bodies must work to neutralize that acid. This means our modern bodies are constantly working to neutralize an acid load that our ancestors never faced.
Evolution and Health Implications
While 10,000 years may seem like a long time, it represents less than 1% of human evolutionary history. Our bodies remain genetically adapted to process the alkaline diet of our ancestors. The constant acid load from contemporary diets forces our bodies to:
- Pull calcium from bones to neutralize acids
- Work harder to maintain kidney function
- Struggle to maintain muscle mass
- Deal with increased inflammation
Making Better Choices
While we can’t return entirely to a paleolithic diet, here’s what we can learn from this research:
- Increase consumption of vegetables and fruits
- Limit grain intake
- Choose whole foods over processed ones
Understanding this acid-base relationship can help us make more informed choices about the balance of foods we eat, potentially reducing our risk of chronic health conditions that may stem from this fundamental mismatch between our ancient biology and modern diet.
