Can Alkaline Water Change Body pH?

Alkaline water

Can Alkaline Water Change Body pH?

It is claimed that consumption of alkaline water provides several health benefits, but there exists a dearth of evidence to support such claims.1 For some time, I have wondered whether the amount of base contained in various brands of alkaline water could have any significant impact on the pH of the body. After all, I figured that the amount of acid in (or produced by) the human stomach could easily neutralize the small amount of base contained in alkaline water. I decided to do some chemical investigations to see if my suspicions were correct.

I first searched through the scientific literature to find out how much acid is contained in the human stomach under normal conditions. I also looked to see if I could find out how rapidly the stomach produces acid. It turns out that the contents of the fasting human stomach have an average pH of 1.52-3 and contain between 35-75 mL of fluid.4-5 Using the lower of these volumes, this works out to 1.1 mmol of H+ in the fasting human stomach:

In addition, the human stomach can produce up to 30 mmol H+ per hour after a meal on average.6 This means the stomach can replenish the 1.1 mmol of H+ present on fasting in only a little over two minutes:

Armed with this information, I tried adding acid in increments of 1.1 mmol H+ (0.366 mL of 3 M HCl) to various brands of water (Video 1).

Video 1: Testing Alkaline Water, , May 4, 2022

 

Given these experiments, claims that alkaline water can significantly alter the pH of your body seem dubious. It appears that stomach acid has no problem neutralizing the small amount of base present in all these brands of water.

I found it interesting that the Fiji brand water had a lower pH than the Essentia brand water, but that it took more acid to neutralize. This comparison of the basic properties of Fiji vs. Essentia water ends up providing a fantastic and simple demonstration of the difference between the strength and concentration of a base. The ingredients list of these waters indicates that Fiji water contains bicarbonate (HCO3-, Kb = 5 x 10-11), while Essentia water contains both bicarbonate and hydrogen phosphate (HPO42-, Kb = 1.6 x 10-7). By comparing the Kb values for each ion, we see that HPO42- is a much better base than HCO3- (over 3,000 times better!). Because of this, small amounts of HPO42- produce much more hydroxide ion (OH-) than HCO3- when dissolved in water:

HCO3-(aq) + H2O ßà H2CO3(aq) + OH-(aq)

HPO42-(aq) + H2O ßà H2PO4-(aq) + OH-(aq)

So even though Fiji contains more basic ions capable of reacting with H+, the basic ions in the Fiji water ionize to produce less OH-. To further test this, I titrated the number of protons required to completely acidify each brand of water, both of which contained 700 mL of liquid. Indeed, Essentia brand water only required 0.57 mmol of H+, whereas the Fiji water required 1.8 mmol of H+. Interestingly, the number of protons required to acidify the bottle of Fiji water matched quite well with the concentration of HCO3- listed on its ingredients label (152 mg L-1 HCO3-):

    

There is so much to investigate here! Are there any other brands of water than have ingredients lists that can be verified upon simple titrations, such as what I did with Fiji water? Are there any brand of water that contain more base than Fiji water? How many protons does it take to neutralize various brands of alkaline and spring water? How many colors of the rainbow can one produce in various brands of and types of  water upon addition of universal indicator – or other indicators?    

In addition to these ideas, these experiments relate to several other chemical concepts. Titrations, neutralization reactions, pH, solution concentration, kinetics, base dissociation constants, and acid-base equilibria…Who knew there was so much interesting chemistry to explore in drinking water?

Happy Experimenting!

References

  1. Fenton, T. R.; Huang, T. Systematic review of the association between dietary acid load, alkaline water, and cancer. BMJ Open, 2016. DOI: 10.1136/bmjopen-2015-010438
  2. Sammon, A. M.; Ndebia, E. J.; Umapathy, E.; Iputo, J. E. 24-Hour Measurement of Gastric pH in Rural South Africa. Gastroenterology Research and Practice, 2015. DOI: 10.1155/2015/658106.
  3. Hartmann, M.; Ehrlich, A.; Fuder, H.; Lüehmann, S.; Emeklibas, S.; Timmer, W.; Wurst, W.; Lüecker, P. W. Equipotent inhibition of gastric acid secretion by equal doses of oral or intravenous pantoprazole. Aliment. Pharmacol. Ther. 1998; 12, 1027-1032.
  4. Mudie, D. M.; Murray, K.; Hoad, C. L.; Pritchard, S. E.; Garnett, M. C.; Amidon, G. L.; Gowland, P. A.; Spiller, R. C.; Amidon, G. E.; Marciani, L. Quantification of Gastrointestinal Liquid Volumes and Distribution Following a 240 mL Dose of Water in the Fasted State. Mol. Pharmaceutics, 2014, 11, 3039-3047.
  5. Babaei, A.; Bhargava, V.; Aalam, S.; Scadeng, M.; Mittal, R. K. Effect of proton pump inhibition on the gastric volume: assessed by magnetic resonance imaging.
  6. Fordtran J. S.; Walsh J. H.; Gastric acid secretion rate and buffer content of the stomach after eating. Results in normal subjects and in patients with duodenal ulcer. J Clin Invest 1973, 52, 645–57.

NGSS

Asking questions and defining problems in grades 9–12 builds from grades K–8 experiences and progresses to formulating, refining, and evaluating empirically testable questions and design problems using models and simulations.

Summary:

Asking questions and defining problems in grades 9–12 builds from grades K–8 experiences and progresses to formulating, refining, and evaluating empirically testable questions and design problems using models and simulations.

questions that challenge the premise(s) of an argument, the interpretation of a data set, or the suitability of a design.

Assessment Boundary:
Clarification:

Scientific questions arise in a variety of ways. They can be driven by curiosity about the world (e.g., Why is the sky blue?). They can be inspired by a model’s or theory’s predictions or by attempts to extend or refine a model or theory (e.g., How does the particle model of matter explain the incompressibility of liquids?). Or they can result from the need to provide better solutions to a problem. For example, the question of why it is impossible to siphon water above a height of 32 feet led Evangelista Torricelli (17th-century inventor of the barometer) to his discoveries about the atmosphere and the identification of a vacuum.

Questions are also important in engineering. Engineers must be able to ask probing questions in order to define an engineering problem. For example, they may ask: What is the need or desire that underlies the problem? What are the criteria (specifications) for a successful solution? What are the constraints? Other questions arise when generating possible solutions: Will this solution meet the design criteria? Can two or more ideas be combined to produce a better solution?

Constructing explanations and designing solutions in 9–12 builds on K–8 experiences and progresses to explanations and designs that are supported by multiple and independent student-generated sources of evidence consistent with scientific ideas, principles, and theories.

Summary:

Constructing explanations and designing solutions in 9–12 builds on K–8 experiences and progresses to explanations and designs that are supported by multiple and independent student-generated sources of evidence consistent with scientific ideas, principles, and theories. Construct and revise an explanation based on valid and reliable evidence obtained from a variety of sources (including students’ own investigations, models, theories, simulations, peer review) and the assumption that theories and laws that describe the natural world operate today as they did in the past and will continue to do so in the future.

Assessment Boundary:
Clarification:

Constructing explanations and designing solutions in 9–12 builds on K–8 experiences and progresses to explanations and designs that are supported by multiple and independent student-generated sources of evidence consistent with scientific ideas, principles, and theories.

Summary:

Constructing explanations and designing solutions in 9–12 builds on K–8 experiences and progresses to explanations and designs that are supported by multiple and independent student-generated sources of evidence consistent with scientific ideas, principles, and theories. Construct and revise an explanation based on valid and reliable evidence obtained from a variety of sources (including students’ own investigations, models, theories, simulations, peer review) and the assumption that theories and laws that describe the natural world operate today as they did in the past and will continue to do so in the future.

Assessment Boundary:
Clarification:

Planning and carrying out investigations in 9-12 builds on K-8 experiences and progresses to include investigations that provide evidence for and test conceptual, mathematical, physical, and empirical models.

Summary:

Planning and carrying out investigations in 9-12 builds on K-8 experiences and progresses to include investigations that provide evidence for and test conceptual, mathematical, physical, and empirical models. Plan and conduct an investigation individually and collaboratively to produce data to serve as the basis for evidence, and in the design: decide on types, how much, and accuracy of data needed to produce reliable measurements and consider limitations on the precision of the data (e.g., number of trials, cost, risk, time), and refine the design accordingly.

Assessment Boundary:
Clarification:

Mathematical and computational thinking at the 9–12 level builds on K–8 and progresses to using algebraic thinking and analysis, a range of linear and nonlinear functions including trigonometric functions, exponentials and logarithms, and computational tools for statistical analysis to analyze, represent, and model data. Simple computational simulations are created and used based on mathematical models of basic assumptions. Use mathematical representations of phenomena to support claims.

Summary:

Mathematical and computational thinking at the 9–12 level builds on K–8 and progresses to using algebraic thinking and analysis, a range of linear and nonlinear functions including trigonometric functions, exponentials and logarithms, and computational tools for statistical analysis to analyze, represent, and model data. Simple computational simulations are created and used based on mathematical models of basic assumptions. Use mathematical representations of phenomena to support claims.

Assessment Boundary:
Clarification:

Students who demonstrate understanding can plan and conduct an investigation of the properties of water and its effects on Earth materials and surface processes.

More information about all DCI for HS-ESS2 can be found and further resources at.

Summary:

Students who demonstrate understanding can plan and conduct an investigation of the properties of water and its effects on Earth materials and surface processes.

Assessment Boundary:
Clarification:

Emphasis is on mechanical and chemical investigations with water and a variety of solid materials to provide the evidence for connections between the hydrologic cycle and system interactions commonly known as the rock cycle. Examples of mechanical investigations include stream transportation and deposition using a stream table, erosion using variations in soil moisture content, or frost wedging by the expansion of water as it freezes. Examples of chemical investigations include chemical weathering and recrystallization (by testing the solubility of different materials) or melt generation (by examining how water lowers the melting temperature of most solids).

Evaluate a Solution to a Real World Problem is a performance expectation related to Engineering Design HS-ETS1.

Summary:

Evaluate a solution to a complex real-world problem based on prioritized criteria and trade-offs that account for a range of constraints, including cost, safety, reliability, and aesthetics as well as possible social, cultural, and environmental impacts.

Assessment Boundary:
Clarification:

Evaluating potential solutions-In their evaluation of a complex real-world problem, students: Generate a list of three or more realistic criteria and two or more constraints, including such relevant factors as cost, safety, reliability, and aesthetics that specifies an acceptable solution to a complex real-world problem; Assign priorities for each criterion and constraint that allows for a logical and systematic evaluation of alternative solution proposals; Analyze (quantitatively where appropriate) and describe* the strengths and weaknesses of the solution with respect to each criterion and constraint, as well as social and cultural acceptability and environmental impacts; Describe possible barriers to implementing each solution, such as cultural, economic, or other sources of resistance to potential solutions; and Provide an evidence-based decision of which solution is optimum, based on prioritized criteria, analysis of the strengths and weaknesses (costs and benefits) of each solution, and barriers to be overcome.

Refining and/or optimizing the design solution: In their evaluation, students describe which parts of the complex real-world problem may remain even if the proposed solution is implemented.