After reading Nicholas’ post on the claim made by the company that produced water ionizers, I was reminded of a similar claim made by advocates of the ‘Alkaline Diet’. I decided to investigate whether these claims were accurate, or like the ones made by the water-ionizer company, scientifically wrong.
The Alkaline Diet is based on the theory that eating specific foods can affect maintenance of the body’s ideal pH balance, and improve health. (Collins & Chang, n.d) A website promoting holistic treatments gave the following reasoning for the diet:
The pH of the blood must always fall between 7.35 and 7.45 (slightly alkaline) to ensure an appropriate concentration of oxygen in the blood. A pH lower than 7.35 (Acidosis) may portray the beginnings of a disease / aging, while a pH higher than 7.45 (Alkalosis) would result in seizure, and a possible coma.
In order to keep the blood within this pH range, the website then explains, 75% of alkaline forming foods must be consumed; however, the American diet consists of 80% of acid forming foods.
The body creates a buffering system in order to counteract this abundance of acidic food in the diet; this buffering system runs on electrolytes, which are important for the metabolic functioning of body systems. Adequate electrolyte supply will pose no problem on the buffer system, however a shortage of these electrolytes will make it difficult for the body to maintain homeostasis (a state of equilibrium). A shortage of electrolytes usually occurs as a cause of excessive consumption of acid forming foods. (Frequency Rising, n.d)
At first, this claim made sense to me. After all, medical websites confirm that the blood’s pH must fall within a certain range. (Collins & Chang, n.d) Furthermore, there is evidence that shows that the concentration of Oxygen in the blood is affected by the blood’s pH, and as I have previously learnt in Biology class, it is true that the pH of blood must remain within a certain range to ensure health. (RSC, n.d) Another medical website mentioned diseases such as Acidosis and Alkalosis, the former caused by a blood pH lower than what it should be, and another caused by a blood pH higher than it should be. (Dugdale & Zieve, n.d) Was the claim made by the holistic website accurate? Upon further examination and reflection, it was clear to me what the problem was: the holistic website was trying to convince people on the basis of a logical fallacy!* Our body deals with acidic food with a buffer system that does not work properly when you consume excessive acidic foods?
That makes no sense.
I soon realized that it was very easy to see the reason they would make this claim, as directly under the article, I saw this.
This reminded me of Nicholas’ post, and confirmed my doubts: it was all just a marketing technique.
I decided to look at the biochemistry myself to determine the validity of the diet.
I found the concentration of Oxygen in the blood is controlled by a separate mechanism: oxygen flows around the body in blood by hemoglobin, a complex molecule with a central ion. (AUS-e-TUTE, n.d) The oxygenation of blood is an equilibrium reaction:
Hb4(aq) + 4O2(aq) <–> Hb4O8(aq)
A number of equilibrium reactions involving hemoglobin are responsible for the buffering of the blood: the net reaction being –
HbH+(aq) + O2(aq) <–> HbO2(aq) + H+(aq)
Metabolic reactions in the body release many acidic compounds, which lowers the blood’s pH by increasing the concentration of H+ ions present in the blood. This in turn, forces the equilibrium position to the left, resulting in acidosis. This decrease in oxygen supply causes fatigue and headaches. Acidosis is also the same condition you experience temporarily when you exercise without warming up, or when you engage in strenuous exercise when the available supply of oxygen cannot meet the demand for energy to complete the oxidation of glucose to carbon dioxide. (AUS-e-TUTE, n.d)
Thus, Acidosis really has nothing to do with what you eat.
Additionally, although electrolytes are important for the body, the only ion that affects the pH of the blood is the Phosphate Ion (PO42-), which is part of the Phosphate Buffer System. (Electrolytes, n.d) However, the primary buffer system for balance of the blood pH’s remains the Hydrogen Carbonate Buffer System.
Hydrogen Carbonate is produced in the body with water and CO2 (the end product of cellular metabolism) with the following reaction:
H2O + CO2 <–> H2CO3(aq)
The Hydrogen Carbonate is then involved in another (can be classified as a Bronsted-Lewry) reaction, which produces bicarbonate and the Hydronium ion:
H2CO3 + H2O <–> H3O+ + HCO3–
If there is excess acid in the body (H3O+), the equilibrium shifts left.
H2CO3 + H2O <– H3O+ + HCO3–
Thus, the excess acid is neutralized by the base (HCO3–)
The reverse takes place if there is excess base (OH–) in the body: this reacts with the carbonic acid (H2CO3) and the equilibrium shifts right.
H2CO3 + OH– <– H2O + HCO3–
This system thus operates under Le Chaletier’s principle, which states that “if a chemical system at equilibrium experiences a change in concentration, temperature, or total pressure, the equilibrium will shift in order to minimize that change ”. This reaction is the main mechanism used by our body to maintain homeostasis.
The Phosphate Buffer System plays a role in plasma and erythrocytes (components of blood)- (Tamarkin, n.d)
H2PO4- + H2O <–> H3O+ + HPO42-
Any excess acid reacts with monohydrogen phosphate to form dihydrogen phosphate –
H2PO4- + H2O <– H3O+ + HPO42-
Similarly, excess base is neutralized by dihydrogen phosphate –
H2PO4- + H2O –> H3O+ + HPO42-
So if this is all true, and the claim that eating alkaline foods can affect blood’s pH is not correct, then why do people continue to follow the Alkaline diet: and how can we explain their success stories?
The Alkaline Diet is “a diet of fresh fruits and vegetables, plenty of water, avoiding processed foods, coffee, and alcohol, which are all recommendations for a generally healthy diet anyway,” says Marjorie Nolan, who is an American Dietetic Association spokeswoman. (Collins & Chang, n.d) This is evident by an Alkaline Diet cheat sheet, which recommends eating cold-pressed olive oil instead of butter, frozen fruit instead of canned fruit, sparkling water instead of soda, honey instead of sugar, and so on. (Wilkinson, n.d) According to Nolan, any diet consisting of this meal plan is bound to prove successful, because it is “basically healthy”. She confirms however, that the body “regulates our pH between 7.35 and 7.45 no matter how we eat.” (Collins & Chang, n.d)
So, what are the implications of this finding?
First, the negative implications: because the Alkaline diets promotes less consumption of dairy products and animal fats, followers of the diet if not careful, may develop calcium and protein deficiencies, according to John Asplin, an MD and kidney specialist. (Collins & Chang, n.d) A vegetarian myself, I was quick to disagree with this statement in my mind, however, he acknowledged that “vegetarians can be completely healthy in their diets, as long as they make sure to get adequate supplies of essential components to a diet.” Asplin also asserted that this could be seen as benefit also, because “many Americans over-consume protein”. (Collins & Chang, n.d) Another implication of this finding is that followers of the Alkaline Diet may not have a scientifically correct view of the functioning of their body, and this could lead to potential problems in the future. Followers of the diet may also waste money on expensive products (such as the water ionizer advertised on the holistic website) that do not affect our body in the way that the manufacturers claim.
What are the benefits? Because excess animal protein results in a higher risk of developing kidney stones, “eating a diet rich in vegetables, as with the alkaline diet” can lower this risk, according to Asplin. (Collins & Chang, n.d) It has also been suggested by research that an alkaline diet may slow bone loss and muscle waste, increase the growth hormone, and reduce the risk of certain chronic diseases (these are correlations however, and cannot be stated as a cause-effect relationship). (Schwalfenberg, 2011)
A negative correlation between the alkaline diet and incidence of cancer has also been shown, however the same results were obtained when the vegetarian diet was measured against cancer rates: additionally, as the study was correlational, there were many confounding variables that may have affected the results such exercise, alcohol consumption, smoking, genetics, etc. (Collins & Chang, n.d)
Nolan speaks of this finding, stating that “clinical studies have proved without a doubt that people who eat more fresh fruits and vegetables and hydrate properly do have lower rates of cancer and other diseases”, but that “it probably has nothing to do with blood pH”. (Collins & Chang, n.d)
The journey I took while examining this diet taught me to properly examine the agenda of the source making a claim before choosing to accept it: because the holistic website was advertising the water ionizer, they made claims that were scientifically inaccurate to make the product seem more appealing to customers. Web MD on the other hand, a medical website dedicated to providing people with factual information on clinical practices, provides evidence and information that supports the knowledge we have of the biochemistry of our body.
Thus, William Mundel, the vice chair of the department of General Internal Medicine at the Mayo Clinic in Rochester, advises against diets that “want you to buy only their product” (i.e.: the water ionizer), “focus on a narrow spectrum of foods” (i.e.: eliminate all animal fats), and “claim that science has kept something secret, or that someone has discovered something that nobody else knows about”. These are the types of diets that tend to be scientifically wrong. (Collins & Chang, n.d)
* The logical fallacy used is Circular Reasoning / Begging the Question.
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