Dr. Sarah King, ND
@sarahhealthyfox
Over the past few years, “alkaline” has become a health buzz word. Alkaline diets, and now new brands of alkaline water, are said to promote a healthier state in the body. The health buzz is that they attempt to alkalinize the body and help to prevent cancer since some cancer cells have been shown to grow faster in acidic environments. Other theories have suggested correlations between acid-heavy diets and osteoporosis, but what is the evidence actually showing?
Acid-base balancing, or pH homeostasis, is present in multiple systems in our bodies; Though these are heavily regulated processes taking place, we as humans tend to think we wield more power in affecting or controlling this balance. For example, we’ll reach for antacids to combat heartburn and acid reflux, taking proton-pump inhibitors (PPIs) and histamine H2-receptor blockers to prevent acid production. But what are we actually doing? What’s happening in our bodies, and are there benefits, or harmful effects? First, we need to clarify what alkaline means. For that, we go back to our general chemistry of acids and bases.
From a chemistry standpoint, alkaline refers to a substance or compound with a pH greater than 7, generally 8-14. Substances with a pH lower than 7 are acidic and become exponentially more acidic as the pH value decreases towards 1. The value represents a measurement of the concentration of hydrogen and hydroxide ions. These ions and intermediate buffers are constantly in play in the body in every system including blood and circulation, lungs and respiration, the kidneys, and the digestive tract.
Each metabolic reaction creates products that may be acidic or alkaline. In chemical reactions, ions and elements can dissociate, changing their structure and composition. What’s important to note is that certain organs and systems need to be acidic in order to protect us. Our skin is one organ system that maintains an acidic environment in order to protect us from microbial overgrowth. Vaginal mucus, with a pH around 4, is also acidic and provides the same protection against bacterial overgrowth1.
Trying to modify the body to be “alkaline” biologically doesn’t make sense, but that’s not to say that there are no risks from consuming a diet high in acid-forming foods such as animal protein. Many inaccurate conclusions have been advertised regarding acidic environments and our health. The human body has multiple buffer systems in place controlling pH levels as needed.
Stomach Acid
The environment inside the stomach normally maintains a pH of 2. This highly acidic environment is necessary to break down food and digest proteins. By introducing foods and water into the stomach, we increase the pH (alkalinize) of the contents in the stomach. The stomach responds by signaling cells to produce and release more hydrochloric acid so that it can bring the pH back to highly acidic levels in order to break down that meal. This acidity is also used to kill any ingested pathogens that can’t survive under these conditions.
After a food mass leaves the stomach, the pancreas immediately starts pouring out enzymes to further breakdown foods while bile and bicarbonate are secreted into the same area to help neutralize the acidic contents that have just come out of the stomach.
In this way, and many others, the pH of the food or liquid we’re consuming doesn’t necessarily change the pH of the body. The metabolites from the breakdown of foods, processed and used by the body, results in new products that have their own pH. For example, if you squeezed out a lemon, the juice has a pH of about 2, but once it’s in your body, it dissociates, changes, and what’s left are metabolites that carry a pH value of about 7 or slightly higher.
Antacids, used for heartburn and gastric reflux, are typically composed of calcium carbonate, a weak base that binds and neutralizes stomach acid, while PPIs and histamine H2-antagonists block stomach acid production. But these actions have consequences: By raising the pH of the stomach (making it less acidic), certain enzymes in the stomach cannot be converted properly, which can hinder digestion.
Current research is investigating the prevalence of food allergies from antacid use. Animal studies have shown that when proper digestion is inhibited by antacid use, foods aren’t broken down properly, and the development of IgE antibodies to these foods increases2. More recently, a clinical study showed that children with gastric acid reflux who were treated with acid suppressors were more likely to be diagnosed with a food allergy than those with acid reflux who were not treated3.
In these cases of acid reflux, practitioners should not forget to address the muscle tone of the lower esophageal sphincter, which is responsible for keeping the top part of the stomach closed, rather than jumping to control and raise the pH of the stomach.
Blood pH, Buffers and Bones
The pH of your blood is tightly controlled with a narrow range of 7.35-7.45. Going beyond this range could lead to serious health consequences; a serum (blood) pH of less than 7.35 puts the body into a life-threatening state of acidemia. Our bodies can’t afford to go out of this range, so it uses buffers to control pH. There are many systems with buffering capacities such as the respiratory and renal systems. Red blood cells use hemoglobin for buffering, while bone also plays a role by releasing sodium bicarbonate and calcium bicarbonate in exchange for acidic hydrogen ions. With prolonged acid loading in the body, bone will eventually begin to release calcium carbonate and calcium phosphate.
As bone tissue tends to release these substances as needed, it has been theorized that highly acidic dietary factors may increase the risk of osteoporosis. However, results in current research has been inconsistent and it is unclear if there exists a true correlation between acid-forming foods and bone fracture risk4.
With the suggestion of an alkaline diet, many people have also been told that pH levels of the body can be measured via urine. With bone minerals able to buffer acidic content, a diet with a high acid-load can lead to measurable calcium in the urine. However, using this observation as a measure of body health has very little scientific backing. Even by measuring calcium levels excreted in the urine, this will not predict nor measure the risk for osteoporosis, nor bone fracture risk1,4.
The body has many other regulating processes to compensate for the loss of calcium and to prevent a weakening of bones. Adequate Vitamin D or supplementation thereof will allow the gastrointestinal tract to absorb more calcium, magnesium and phosphate from the diet when it’s needed1. A high amount of dietary acid, typically from high amounts of animal proteins and grain carbohydrates and low vegetable and fruit intake, has not yet been associated with an increase in bone fracture risk or the diagnosis of osteoporosis5.
Dietary factors affecting body pH
Following a strict alkaline diet might make you feel better, but it’s much easier to say, eat a lot of vegetables! An extreme diet composed mostly of cereal grains and animal proteins, deficient in vegetables, long term can cause a low-grade metabolic acidosis as was measured in the blood6. This drastic modification in serum pH is more likely to occur in the elderly as we tend to gradually lose the regulation of acid-base buffering in the kidneys as we age1,6. Though this is a dangerous outcome, it is based on an extreme diet and can easily be altered by making changes, increasing the ratio of vegetables to acid-forming animal proteins and grain carbohydrates.
Short-term, a highly acid-forming diet will result in very little change in blood pH level due to our buffering mechanisms, however, urinary pH changes may occur. This may be why those an Alkaline diet are told use measure the pH of their urine, however, there is no correlation between this value and the pH of the blood. Even urinary calcium can’t give us enough information due to the fact that there are other buffering substances at play such as phosphate6.
So the answer to this alkaline-diet debate is simple: Protein is absolutely necessary in our bodies, but increasing the amount of vegetables and fruits in our diet is crucial. We currently do not have the scientific evidence that an alkaline diet itself will prevent cancer or osteoporosis via serum pH modification, but vegetables themselves have properties that can help decrease our risk of certain cancers and osteoporosis via antioxidants and micronutrients, respectively.
Dietary minerals play a huge role in reducing the risk for osteoporosis as well as promoting the function of many enzyme systems within the body. There may be a benefit from mineral supplementation, especially in the elderly as our kidney’s buffering capacity tends to slow as we age. But there are simple guidelines that can we can apply to assist in the body’s normal and healthy functioning:
- Eat lots of vegetables and include 1-2 servings of fruit per day
- Consume enough dietary protein (0.8g-2g of protein per Kg of body weight, depending on level and daily duration of physical activity)
- Exercise, to maintain muscle mass, and for protection of bones and reduction in osteoporosis risk (form and duration of exercise will vary from person to person)
Dr. Sarah King is a licensed Naturopathic Doctor, graduating from the Canadian College of Naturopathic Medicine in 2014. Prior to completing her medical studies, she attended Nipissing University where she received her Honors Bachelor of Science in Biology. Sarah has a passion for women’s health and is a birth doula in Durham and Toronto Region. She treats a wide variety of health conditions including menstrual disorders and hormone balancing, fertility, prenatal care, digestive concerns, skincare and mental health/anxiety. Outside the office Sarah is an avid runner with a love of the GTA’s best forest trails. She also continues to improve her yoga practice and teaches breath work as part of stress management counselling to her patients.
References:
1 Schwalfenberg, G.K “The Alkaline Diet: Is there evidence that an alkaline pH diet benefits health?” (2012) J Environ Public Health. 2012:727630
2 Pali-School, I., Herzog, R., Wallmann, J., Szalai, K., et al. “Antacids and dietary supplements with an influence on the gastric pH increase the risk for food sensitization” (2010). Clin. Exp Allergy. 40(7):1091-8
3 Trikha, A., Baillargeon, J.G., Kuo, Y-F., Tan, A., et al. “Development of food allergies in patients with Gastroesophageal Reflux Disease treated with gastric acid suppressive medications” (2013) Pediatr Allergy Immunol. 24(6):582-588
4 Hanley, D.A. and Whiting, S.J. “Does a high dietary acid content cause bone loss, and can bone loss be prevented with an alkaline diet?” (2013). J Clin Densitom. 16(4):420-5
5 Jia, T., Byberg, L., Lindholm, B., Larsson, T.E., et al. “Dietary acid load, kidney function, osteoporosis, and risk of fractures in elderly men and women” (2015) Osteoporos Int. 26(2):563-70
6 Hietavala, E.M, Stout, J.R., Hulmi, J.J., Suominen, H., et al. “Effect on diet composition on acid-base balance in adolescents, young adults and elderly at rest and during exercise” (2015) Eur J Clin Nutr. 69(3):399-404