Note: This page has been completely revised and updated. It reflects new research that sheds important new light on the PH hypothesis and correlates this with what is contained in the historical record and what the forgotten research of luminaries such as T. L. Cleave, George Mann and Weston Price showed. Many thanks to clinical herbalist, author and teacher Thomas Easley for his help.

It is not a stretch to say that the vast majority of health practitioners today see a strong relationship between a wide variety of disease conditions and an "overly acid" or "overly alkaline" body terrain. Armed with the belief that an “alkaline diet” helps individuals maintain proper pH or acid-alkaline balance, most health practitioners advocate a diet that includes 80% alkaline-forming foods (mostly fruits and vegetables) and 20% acid-forming foods (meats, dairy, beans, grains, sugar and caffeine).

There are several significant problems associated with this theory. The first is that there is a plethora of deeply conflicting or inconsistent information on just which foods are alkaline and which are acid (or neutral) - and why they have been categorized as such. This conflict surfaces in the acid/alkaline food charts themselves and clouds the “pH” debate even as it manages to ignore the nutritive contribution, or lack thereof, of individual foods. As one example, we find some very unhealthy foods included in the alkaline category - leaving one with the impression that these foods are acceptable components of a “healthy” alkaline-based diet. Animal protein, irrespective of nutritive value, are classified as acid forming. Similarly fats - while often classified as neutral, appear with nary a mention of the critical role played by healthy animal and other saturated fats in human metabolism.

In addition to this conundrum, we can find, for example, that some acid/alkaline charts say that the residues from raw, unprocessed milk and cheeses made from such milk form "acid ash" when burned in a lab but they are "alkaline-forming" in the body. You will also find tables and lists that variously classify milk in the neutral, alkaline or acid categories with no explanation or reason for the classification. In fact, numerous lists of alkaline and acid foods can be found on the internet and in print literature that have little or no agreement between them on any number of foods or food categories. What we end up with is more confusion than clarity.

It is true that alkaline foods leave behind alkaline ash and acid foods leave behind acid ash that can make urine acid or alkaline. Bechamp's colleague Claude Bernard proved this in the mid-nineteenth century. What seems to have escaped modern thinking however, is that urine is the ONLY body fluid whose pH can be changed by food, medicines or supplements.

Food, whether it be “alkaline” or “acid,” must go through the stomach. At the time that said food, be it alkaline or acid, reaches the stomach, the stomach has a pH of only around 1 or 2, or very acidic - this due to the secretion of hydrochloric acid. Prolonged attempts to neutralize stomach acid via ant-acid tablets or similar methods will lead to nutritional deficiencies, acid reflux, further decline in the production of stomach acid (due to decreased methylation needed to produce stomach acid) and numerous other undesirable health consequences. In fact, research shows that acid reflux and indigestion are actually due to too little acid production - not too much. This is why acidic foods like pickles and sauerkraut or a drink made with water and raw, unfiltered apple cider vinegar and maybe some raw, unheated, unfiltered honey are often used to solve such issues - and they do this by stimulating production of acid.

Once the stomach has done its work in an initial acidic environment, various natural buffering mechanisms will help raise stomach pH to about 4 or 5 by the time the food mass, or chyme, leaves the stomach. When the “chyme” mixture moves to the small intestine the secretion of sodium bicarbonate causes pH to become slightly alkali, somewhere between 7 and 8. The pH fluctuates slightly as the food mass moves through the intestines reaching a final pH of around 7 by the time it exits the body. This is essentially the process that occurs in a reasonably healthy body, regardless of whether the food eaten was alkaline or acid.

Meanwhile, food solids are separated from liquids as the food mixture makes it way through the digestive tract. These liquids will be filtered by the kidneys and collected in the bladder as urine. Normal pH values for urine can range from 4.6 to 8 and are affected by food, drugs or supplements. So again, urine is the ONLY body fluid whose pH can be changed by food, drugs or supplements.

The well known, undisputed scientific fact is that the body has numerous, highly redundant systems to maintain pH within a narrow range. This is the reason why alkalosis or acidosis are rarely ever seen. The bottom line is that we cannot influence our blood and intracellular pH simply by eating a more "alkaline" diet, the reason being that our body tightly regulates blood pH and extracellular fluid via numerous “buffering” mechanisms. In fact, a more detailed and scientific explanation of these buffering mechanisms tells you, among other things, that not only are proteins the most important buffers in the body but a situation in which there are little or no protein (or phosphate) buffers is incompatible with life. In short and absent only very serious illness, pH regulation is a continuous, on-going process necessary to sustain life and your body has numerous, highly redundant systems to accomplish that particular goal.

This being said, and as already mentioned, the foods that we eat DO leave behind acid or alkaline ash, and the foods we eat WILL change urine pH. The problem is that not only is urine pH not a good indicator of blood or body pH but urine pH is not necessarily a good or reliable indicator of health.

This likely comes as a bit of a surprise to those of us who take it as a matter of faith that managing acid/alkaline balance via ingestion of copious amounts of alkaline or plant-based foods and minimal amounts of acid foods is essential if we want to assure long term robust health. Yet the historical record as uncovered by paleopathologists, anthropologists, archeologists and food historians clearly tells us otherwise: evidence that carbohydrates contributed to poor health can be found from fossils both before and after paleolithic times, say Drs. Alan and Lutz, in their book Life without Bread.

The historical record, objectively considered, is also backed up by impressive research carried out by the likes of T.L. Cleave, Vilhjalmer Stefansson, George V. Mann, Weston Price and others. And however inconvenient to modern agriculture, the food industry, and the USDA, the underlying truth of this research is now being re-confirmed by ongoing academic study.

Thus, the findings of one recent meta-analysis published in 2013 found that although “the [acid urine] hypothesis was later refuted on the basis of both theoretical and experimental arguments. . . the hypothesis was put forward that bone could play a buffering role, with the consideration that nutrients, particularly animal proteins with their acid load, could be a major cause of osteoporosis. Several recent human studies have shown that there is no relationship between nutritionally induced variations of urinary acid excretion and Ca balance, bone metabolism and the risk of osteoporotic fractures. Variations in human diets across a plausible range of intakes have been shown to have no effect on blood pH.”

Another meta-analyses published in 2010 found that “as our present analysis of the diets consumed by the 229 historically studied hunter-gatherer societies listed in the Ethnographic Atlas clearly indicates, a high proportion of historically studied hunter-gatherer diets are characterized by a net acid load. . . . . . . .Regardless of the model used, our data presented here clearly show that a high proportion of the non-agriculturally based diets of historically studied hunter-gatherer societies were net acid producing.” [As our Grain Timeline shows, archaeologists and paleopathologists, among others, have consistently found that hunter-gatherers had higher levels of health than their agricultural-based counterparts.]

Yet another meta-analyses published in 2009 found that “there is no evidence from superior quality balance studies that increasing the acid load promotes skeletal bone mineral loss or osteoporosis. . . Promotion of the “alkaline diet” to prevent calcium loss is not justified.”

A study published in 1999 found that a high protein [i.e. acid] diet did not increase risk of heart disease. On the contrary, the study findings “suggest that replacing carbohydrates with protein may be associated with a lower risk of ischemic heart disease.”

Another study, published in 1999, concluded that “Intake of dietary protein, especially from animal sources, may be associated with a reduced incidence of hip fractures in postmenopausal women”.

And another published in 2002 found that there was a protective role for dietary animal protein in the skeletal health of elderly women.

Another study published in 2001 found that “In contrast to the [acid-base] hypothesis, higher rather than lower protein intakes were associated with lower bone loss.”

Yet another meta-analyses published in 2010 concluded that low urine pH and acid excretion do not predict bone fractures, the loss of bone mineral density or osteoporosis risk.

Again, and along these same lines, another meta-analyses published in 2003 found that while higher levels of protein intake did increase urinary calcium it also increased calcium absorption from the intestines. The high acid load thought to be generated by a protein-rich diet did not result in increased skeletal fracture, and there were no definitive nutrition intervention studies found that showed a detrimental effect of a high protein diet on the skeleton. Conversely, low protein diets, the study found, not only decreased intestinal calcium absorption but the majority of recent epidemiological studies surveyed showed that lower protein diets are associated with reduced bone mass. Essentially this meta-analysis held that while the acid/alkaline hypotheses identifies symptoms, it mistakenly correlates these symptoms with improper pH. In short, the acid/alkaline hypothesis does not provide adequate mechanism of action nor can it explain causation.

We could go on, but the point should be clear enough by now that the acid/alkaline hypothesis is not as cut-and-dried as we might think. The research of Weston Price allowed him to see this. Even when popular opinion was moving in the opposite direction he continued to speak his piece.

So it was that just as the alkaline diet “enthusiasts” were coming into prominence in the late 1920s and early 1930's Weston Price took every opportunity to publicly weigh in with his own findings, asserting that “a great deal of propaganda is reaching the profession and laity which places great stress upon the importance of keeping the diet potentially alkaline” - thus leading to the marginalization of acid foods found by Price to confer robust, disease-resistant health.

Price it should be noted funded his own research and cannot be accused of bending to the needs or requirements of institutional or business-related funding sources. This is particularly evident in his recommendations to displace white flour, sugars and similar “foods of commerce” with nutrient dense foods like butter or milk obtained from cows that are eating fresh or cured rapidly growing green wheat or rye. Not exactly the kinds of foods that are well suited to the current industrial food/ag model for sure.

In a 1934 speech given at the New York Dental Centennial Meeting Price pointed out the following:

It is important to note that in four of these five groups of primitive racial stocks, living on entirely different native foods and in widely divergent climates and entirely different living habits, the immunity-producing diets were found to be higher in acid factors than in base factors. In some the divergence is quite small and in others, quite large. It is also important that, in changing from high immunity to high susceptibility diets, there was no increase in potential acidity with increased susceptibility to tooth decay. . .

In no instance have I found the change from a high immunity to dental caries to a high susceptibility among these primitive racial stocks to be associated with a change from a diet with a high potential alkalinity to a high potential acidity, as would seem to have been the case had the high alkalinity balance theory been the correct explanation. If the requisite is as simple as a potential alkalinity, why has not the addition of sodium bicarbonate to a deficient diet controlled dental caries?

What made Weston Price's research particularly unique and valuable is that he was able to travel to the far corners of the globe to study cultures that were still following traditional dietary patterns and who often lived side-by-side with their modernized counterparts consuming the “foods of commerce.” This allowed him to compare the two groups (modern and traditional) by chemically analyzing the foods contained in widely varying diets for their nutrient content and then distilling this information into the kinds of nutrients, as supplied from food, that made some cultures healthy and what made their counterparts unhealthy by comparison. In so doing he discovered that those who adhered to “traditional” diets containing ample amounts of animal protein and fat but no “foods of commerce” exhibited no dental decay, misshapen dental arches or crowded teeth. The traditional peoples whose diets were higher in acid factors always had higher resistance to all disease, and often possessed superior physical strength, as well as visual and mental acuity than their more "modernized" counterparts.

Indeed, Price found that those cultures that were the strongest physically and often 100% resistant to dental disease were those that relied primarily on animal fats and proteins. In sum, Price's meticulous analysis clearly showed that the diets of the healthy primitive peoples all over the world were actually higher in "acid-ash" foods than "alkaline-ash" foods - exactly as high quality modern research has been verifying.

A major part of our current confusion, says Thomas Easley, stems from the fact that most people are not differentiating between cause, symptoms, correlation and mechanism of action. We look at symptoms such as fatigue, joint pain, bone loss, cancer and so forth and assume that an acidic pH is the cause. But in order to prove causation we need to have a plausible mechanism of action, and here the pH theory falls apart.

For example, says Easley, we associate cancer with an acid pH and yet cancer can grow just fine in normal pH. In fact, cancer cells are grown in petri dishes which have a pH of 7.4, which is slightly alkaline. The misunderstanding, says Easley, comes from the fact that when tumors get large enough, they actually start producing their own acid - lactic acid specifically - because of their “crazy” glucose metabolism. This is what Linus Pauling showed in his research.

The failure of the pH hypothesis to explain mechanization of action is especially intriguing when it comes to explaining the role of saturated fats that Weston Price, among others, found to be so crucial to maintaining life-long optimal health. And while it is true that the pH-regulating system of the body is very complex and made up of many parts, it is the kidneys and lungs which are the two main organs involved in regulating proper pH. So what kinds of foods are required to maintain healthy lungs and kidneys, capable of properly regulating pH? It is precisely those foods containing those key fat soluble vitamins named by Price and which are most abundantly found in shellfish and high fat organ meats and good quality butter, as well as fish roe, and raw milk, yogurt, kefir and cheeses made from the milk of healthy, fully pastured animals. These kinds of foods are also needed by our organs and glands in order to produce essential hormones, neurotransmitters, digestive enzymes and other elements needed to properly regulate as well as carry out all metabolic processes.

The reader, it is hoped, will verify the above statements at his leisure. For now, and for the purposes of this article, let's look at the kidneys. Basically the role of the kidneys is to filter out most of the excess uric acid that may be present in the blood and then pass this waste out in urine. Uric acid, says WEBMD, is produced from the natural breakdown of your body's cells and from the foods you eat. A certain amount of uric acid is essential to health, and low uric acid levels are associated with MS.

But high levels of uric acid, which can be caused when your body either produces too much uric acid or your kidneys don't eliminate it fast enough, can cause solid crystals to form within joints, causing gout in some people. High uric acid levels can also cause some people to develop kidney stones and kidney failure. Still others may develop high blood pressure, heart disease or chronic kidney disease. And according to Dr. Ray Sahelian, older adults with high uric acid levels are significantly more likely than those with low-moderate concentrations to experience mild cognitive impairment (loss of mental ability or memory.) High blood levels of uric acid are also a strong predictor of death from cardiovascular disease, stroke and all causes.

So what foods cause undesirably high uric acid levels and what kinds of foods help the body eliminate excess uric acid. Science is revealing some less-than-shocking answers:

One recent study focusing on a nationally representative sample of U.S. adolescents, published in 2010, found that “higher sugar sweetened beverage consumption is associated with higher serum uric acid levels and systolic blood pressure, which may lead downstream to adverse health outcomes.”

Another study published in 2013 started with the premise that “the intake of added sugars, such as from table sugar (sucrose) and high fructose corn syrup has increased dramatically in the last hundred years and correlates closely with the rise in obesity, metabolic syndrome and diabetes.” It concluded by saying that while more studies are needed, the evidence shows that fructose-induced hyperuricemia may have a contributory role in diabetes and that uric acid may have a fundamental role in metabolic syndrome.

Surprisingly, a 2012 study published in Nutrition Journal started with the goal of testing the results of a previous study which found that alkalization of urine facilitates uric acid excretion. This goal was formulated because the results of the previous study were “contradictory to what one might expect to occur.” The conclusion of this follow-up study was that “alkalization of urine by eating nutritionally well-designed alkaline-prone food is effective for removing uric acid from the body.”

So in summary, to quote Thomas Easley, it is accurate to say that eating more green vegetables is correlated with better health. But the mechanism of action by which vegetables increase health has nothing to do with pH.