The standard Western-type diet is a processed food-dominated diet with high levels of animal product consumption. This type of diet is severely lacking in not just green leafy vegetables but also in all types of nutrient-dense and antioxidant-rich whole food sources and contains extreme amounts of high-quality animal protein.

One of the results of this type of diet is the promotion and accumulation of non-metabolizable anions and a condition that significantly worsens in aging because of the physiological decrease in kidney function.

In response to this type of diet-induced metabolic acidosis, the kidneys will implement different metabolic pathways that aim at reestablishing the acid-base equilibrium. This will have a negative health correlation in the long run. Some metabolic processes in diet-induced acidity (metabolic acidosis) include the extraction of the non-metabolizable anions, the preservation of citrate, and the increase in kidney ammoniagenesis and urinary excretion of ammonium particles.

These metabolic processes will bring down the urinary pH but will also promote a broad change in urinary synthesis, including hypercalciuria, hypocitraturia,  and nitrogen and phosphate removal.

The negative side effect of this is the promotion of calcium stone development.

What is even worse than stones is the fact that even extremely mild levels of metabolic acidosis prompt serious health diseases like skeletal muscle insulin resistance and kidney failure. Results of observational studies had proven the health risk correlation in insulin resistance and diabetes with all metabolic acidosis markers, including low serum bicarbonate, high serum anion gap, hypocitraturia, and low urine pH.  Also, the acid burden might be a significant variable in the cardiovascular disease risk for the entire population on top of the risk of obesity (1).

Most people when they hear “acid-forming food” just think about calcium loss not realizing the scope of the problem.

Calcium loss as a consequence of a high-quality animal protein-rich diet is a scientific consensus. And it is a reasonable hypothesis that by eating acid-forming food (like meat), our body will use calcium to buffer it and as a result, we were, fundamentally, in danger of urinating our bones out. This hypothesis was backed by the fact that when we do eat high protein diet we get an increase in urinary calcium concentrations.

Calcium testing showed in all situations that when we add high protein sources like meat or eggs or dairy the rise in calcium will correspond to the amount of protein added. The hypothesis due to the testing was introduced, and this was at beginning of the 20th century, that animal products, not just meat are acid-forming food. Later testing showed that plant-based whole foods are both aced forming and alkaline but mostly alkaline.

In acid reflux, people will use calcium pills to try to buffer the stomach acid so this is nothing new. Calcium carbonate (chalk) treats heartburn and upset stomach, or other conditions caused by too much stomach acid.

But what about the rest of the body in a standard American animal products-dominated diet?

Meat and eggs have a great deal of sulfur-containing amino acids. Amino acids are building blocks of protein and not all of them are made equal. Meat has two to in some cases four times more sulfur-containing amino acids than beans or grains for example and much more than in common vegetables.

That sulfur creates sulfuric acid by oxidation of protein, which needs to be neutralized by the kidneys.

There was even a debate about dairy for a long time because of this. Milk was considered to be a good source of calcium but also a source of protein that needs to be buffered by calcium. In the end, dairy might not be a good source of calcium when we calculate calcium loss due to metabolic acidosis.

One step further will be a question of how much calcium we need to consume on a standard protein-dominated western diet if we have to calculate calcium loss.

If we don’t take enough calcium and calcium deficiency is a common deficiency then where will our body pull the calcium from? The logical answer will be from the bones.

This is especially problematic for people with already-developed osteoporosis. For every 40 grams of protein we add to our diet, and in the SAD (standard American diet) average is 90 grams a day, the loss of calcium in our urine will be around 50mg. If you are already calcium deficient or in a risk group for osteoporosis, this would translate into a two percent loss in a year. We just have around two pounds of calcium in total stored whiting our body including bones. Our bodies need 30 grams of protein at max rest of the protein goes for gluconeogenesis, around 60 grams in SAD. At average. That is 75mg a day of calcium loss multiplied by 365 is 27375mg of calcium loss. This is 27grams and we have a total of around 2000grams for about 1,5 to 2 percent of total loss annually.

If you are calcium deficient and on a high protein diet especially a high-quality protein diet this can be one of the problems. If you are not calcium deficient then the body will just pull more of the calcium from the diet as a defense mechanism. There was a study that proved that if there is calcium in the food our body will pull additional amounts to buffer the acids. They gave subjects radioactive calcium and also increased protein in their diet. Then scientist measure an increase in urinary calcium loss with a special emphasis on radioactivity. The calcium loss did increase but all of the urinary calcium or most of it around 90 percent was radioactive. An increase in dietary protein created an increase in calcium retention from 20% to 26%. There is still no consensus among scientists on how dietary protein helps calcium assimilation but if there is calcium in the meal it will be more bioavailable due to protein.

The problem arises in situations with already preexisting calcium deficiency.

One other problem is aging.

If there is already preexisting calcium deficiency where will our body pull additional calcium to buffer the acids and also what happens in aging? As we age our blood gets more acidic due to renal decline. The worst scenario is in patients with renal disease. They have strictly regulated protein intake monitored by certified dietitians.

In these situations, excess acids will be buffered from calcium that has to be pulled from our body, and the first on the line is not bone calcium.

It is pulled from the muscles.

Catabolism of the muscle tissue will be a primary source for acid neutralization. Muscle wasting appears to be an adaptive response, to acidosis. When our body catabolizes muscle protein it would have a source of the amino acid l-glutamine that will come out of a catabolized protein. Then it will use glutamine to neutralize acids (20).

Glutamine is a common anti-catabolic muscle-building supplement that bodybuilders like to use.

It might be a good idea if you don’t have an adequate intake of calcium to at least add glutamine as a supplement if for any reason you don’t want to decrease protein consumption. And no you cannot eat calcium carbonate chalk or any other mineral as a supplement. Minerals are only able to be fully bioavailable for biochemical processes if they are small enough in physical size or if they are in the monoatomic form that plants create.

In sarcopenia due to protein wasting in aging the common practice is to increase protein requirements for the elderly and also to add a calcium supplement. This is done because calcium is needed to buffer the metabolic acidosis that will be a consequence of an increase in dietary protein. If not corrected this low level of chronic metabolic acidosis will contribute to both osteoporosis and muscle wasting in old age.

For people eating SAD the amount of calcium needed to buffer acidity is a minimum of 800mg a day.

In correlation African women in rural parts of the continent don’t get osteoporosis on average of 300mg of calcium a day. In aging, you don’t have to drink milk to get calcium or eat meat to get protein. Beans for example have as much protein as meat but are not acid-forming. Poppy seeds have 1,4 times more calcium in 100 grams than 1litre of milk and sesame seeds have the same amount of calcium in 100 grams as 1litre of milk. Grains and some seeds like sunflower seeds are mildly acidic, not at the same level as meat but also sunflower seeds are one of the rarely available sources of vitamin E and it is a must in most diet plans.

The one solution will be to stop eating a high-quality protein diet because there are other health risk factors correlated with it than just metabolic acidosis that can be easily corrected if it exists in the first place.

In evolutionary terms all hominin diets were plant-based. This means that our body unlike the bodies of carnivores species had not evolved to cope well with a chronic acid-forming diet. Hominin diets based on whole food plant-based sources were more base than acid-forming.

There are two categories basically. Animal protein-rich foods that promote acid formation and metabolic acidosis and fruits and vegetables are base-inducing foods. More about alkaline diets will be disgusted in correlated articles. Dietary acid load (DAL) is calculated as the sum of all of the food we have eaten during the day. DAL needs to be in normal ranges because it is correlated to more serious diseases like kidney damage. Other correlations include independently of any other factor of insulin resistance and cardiovascular disease. It is not just a question of calcium loss. You can read more about health risk correlations with a high protein diet in a correlated article about this (High protein diet- Health risk correlations).

When we consider just chronic low-level acidity caused by a western type diet without any other correlation, just metabolic acidosis by itself is correlated to: ²

• Insulin resistance and type 2 diabetes.
• Increased gluconeogenesis (conversion of amino acids to glucose).
• Hypertension.
• Bone loss in calcium deficient individuals.
• Osteoporosis/osteopenia/sarcopenia in calcium deficient individuals.
• Muscle loss and reduced muscle strength in calcium deficient individuals.
• Connective tissue loss in calcium deficient individuals.
• Fibromyalgia.
• Hyperuriceamia (too much uric acid in your blood) and gout.
• Kidney function damage and decline.
• Kidney stones independent from renal decline.
  • Less citrate to bind to calcium and more calcium to oxalic acid increasing calcium oxalate stone formation.
  • Reduced urine pH increasing uric acid stone formation.
  • Negative sodium and chloride balance.
• Salt loss and mineral deficiencies.
  • Increased loss of sodium, chloride, potassium, calcium, magnesium, sulfate, and phosphate out of the urine.
  • The sodium and potassium loss are due to a decrease in the reabsorption of these minerals by the kidneys, which likely reduces the reabsorption of taurine
  • The loss of calcium, magnesium, and phosphate is from bone losses
• Taurine loss
• Increased water loss out the urine.
  • Dehydration.
• Decreased exercise performance.

Why low-grade acidosis is so common in the standard American diet:

• The average diet in the Western world leads to a net acid excretion of 50–100 mEq/day.
• The kidneys must be relied on to prevent low-grade acidosis as the lungs cannot affect acid-base status over the long run.
• The kidneys of a healthy person can only excrete 40–70 mEq of acid per day before the acid is retained in the body.
• Animal-based, keto or carnivore-type diets typically provide 150–250 mEq of acid per day.
• Once the kidneys reach their threshold approximately 1 mEq of acid is retained per 2.5 mEq of acid above the threshold.
• If the diet does not contain enough bicarbonate (bicarbonate-forming substances or citrate) and minerals (sodium, potassium, magnesium, and calcium) to neutralize the excess acid then negative consequences to numerous bodily systems take place.

The solution for this is simple as it can be. Balance your DAL with fruits and vegetables if you don’t want to change your diet. Add nutrient-dense, mineral-rich, antioxidant-rich fruits and vegetables on top of your SAD diet as a first step.  Add 100grams of raw sesame seeds into your muesli and it would help your body to neutralize some of the metabolic acidosis. This will be a step to prevent acidity from the diet and nothing else. However, other health consequences of high-quality protein-dominated diets cannot be so easily avoided.

Sources:

Passages selected from a book: “Go Vegan? Review of Science: Part 2” [Milos Pokimica]

1. M. M. Adeva, G. Souto. Diet-induced metabolic acidosis. Clin Nutr 2011 30(4):416 – 421.
2. Low-grade metabolic acidosis as a driver of chronic disease: a 21st century public health crisis http://dx.doi.org/10.1136/openhrt-2021-001730
3.  Dietary protein and bone health: Harmonizing conflicting theories. Nutr. Rev. 2011 69(4):215 – 230.
4. Protein intake, calcium balance and health consequences. Eur J Clin Nutr 2012 66(3):281 – 295.
5. The impact of dietary protein on calcium absorption and kinetic measures of bone turnover in women. J. Clin. Endocrinol. Metab. 2005 90(1):26 – 31.
6. A diet high in meat protein and potential renal acid load increases fractional calcium absorption and urinary calcium excretion without affecting markers of bone resorption or formation in postmenopausal women. J. Nutr. 2011 141(3):391 – 397.
7. Estimated net acid excretion inversely correlates with urine pH in vegans, lacto-ovo vegetarians, and omnivores. J Ren Nutr 2008 18(5):456 – 465.
8. The alkaline diet: Is there evidence that an alkaline pH diet benefits health? J Environ Public Health 2012. 2012:727630.
9. Alkaline diets favor lean tissue mass in older adults. Am. J. Clin. Nutr. 2008 87(3):662 – 665.
10. Vegetarianism: advantages and drawbacks in patients with chronic kidney diseases. J Ren Nutr. 2013 Nov;23(6):399-405. J Ren Nutr. 2013 Nov;23(6):399-405.
11. The key to halting progression of CKD might be in the produce market, not in the pharmacy. Kidney Int. 2012 Jan;81(1):7-9.
12. The balance of acid-forming and base-forming elements in foods, and its relation to ammonia metabolism. J. Biol. Chem. 1912, 11:323-338.
13. Calcium requirement of maintenance in man. J. Biol. Chem. 1920, 44:21-27.
14. Low protein intake: The impact on calcium and bone homeostasis in humans. J. Nutr. 2003 133(3):855S – 861S.
15. Age and systemic acid-base equilibrium: Analysis of published data. J. Gerontol. A Biol. Sci. Med. Sci. 1996 51(1):B91 – B99.
16. A comparison of treating metabolic acidosis in CKD stage 4 hypertensive kidney disease with fruits and vegetables or sodium bicarbonate. Clin J Am Soc Nephrol. 2013 Mar;8(3):371-81.
17. Estimation of the net acid load of the diet of ancestral preagricultural Homo sapiens and their hominid ancestors. Am J Clin Nutr. 2002 Dec;76(6):1308-16.
18. Nutrient based estimation of acid-base balance in vegetarians and non-vegetarians. Plant Foods Hum Nutr. 2010 Mar;65(1):77-82.
19. Glutamine metabolism: Role in acid-base balance doi: 10.1002/bmb.2004.494032050388.

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