With all of the information available right at our fingertips, the potential to stumble upon diet myths is fairly high. During the age of information-overload, how do you know you’re getting accurate facts rather than hyped-up hyperbole?
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This is part one of a ten part mythbusters series on acid reflux relief. I’ll dive into the top ten myths surrounding acid reflux and present you with the facts. Each article will explore why this myth became popular in the first place and what the current research has to say about it. I’ll use the mythbuster-scaling system of totally true, a little bit true, or not true at all. Part one explores the statement: Acidic foods cause acid reflux. Is this fact or fiction?
Read on to find out!
To review “Acidity 101” let’s go over the science of potential hydrogen, also referred to as pH. A scale of 0 to 14 is used to express the pH of any substance.
- 0 to 6.9= acidic
- 7.0= neutral
- 7.1 to 14= alkaline, or basic
While 0 to 14 may not seem like a wide scale, each unit difference in pH corresponds to a 10-fold change. That’s pretty drastic!
Fluids within the human body have certain pH levels that optimize physiology. This means that if the pH of a specific area is not within the optimal range, things will not work as they should. For instance, the pH of blood is 7.35 to 7.45. If this range is too low (acidic), then cell metabolism does not function properly. Therefore, the body will do everything in its power to correct this altered pH level by excreting more acid in the urine.
On the other hand, the pH of stomach acid is 1.5 to 3.5, acidic enough to burn through a nail! If this range is too high (alkaline), then the stomach will not complete its vital duties of breaking down foods, killing off pathogens, and prompting the next steps in digestion.
|Organ, fluid or membrane||pH||Function of pH|
|1) Skin||4.0 to 6.5||Barrier protection from microbes|
|2) Urine||4.6 to 8.0||Limit overgrowth of microbes|
|3) Gastric||1.35 to 3.5||Break down protein|
|4) Bile||7.6 to 8.8||Neutralize stomach acid, aid in digestion|
|5) Pancreatic fluid||8.8||Neutralize stomach acid, aid in digestion|
|6) Vaginal fluid||<4.7||Limit overgrowth of opportunistic microbes|
|7) Cerebrospinal fluid||7.3||Bathes the exterior of the brain|
|8) Intracellular fluid||6.0–7.2||Due to acid production in cells|
|9) Serum venous||7.35||Tightly regulated|
|10) Serum arterial||7.4||Tightly regulated|
In the end, the body always seeks homeostasis.
What are acidic foods?
Those who suffer from acid reflux are commonly told to “stay away from acidic foods” amongst other irritating foods. Acidic foods include coffee, tea, soda, tomato products, and citrus fruits.
However, the term “acidic” is confusing when it comes to foods.
Every food has a pH that may be measured both before and after digestion. Before digestion, the pH of a food can be assessed with a pH test strip fairly easily. Here’s a list by the FDA that presents the pH scale of various foods prior to digestion. Foods like fruits and vegetables have a pretty low pH (more acidic), versus eggs, milk and fish have a higher pH (more basic/alkaline).
Measuring the pH after digestion is commonly referred to the acid ash of a food. Think of your body like a furnace. When you put food into the furnace, it burns and the residue leftover is the ash. To measure this acidity level, researchers use a metric called the potential renal acid load (PRAL) based on consuming 100 grams of that food. The PRAL, on a scale of -3 to 23.6, predicts the effect of the food on the acidity of the urine.
Here is a list of the PRAL of common foods: (the lower the PRAL, the less impact on urine acidity)
|Food group||PRAL (mEq)|
|Fats and oils||0|
|Fruits and fruit juices||−3.1|
|Meat and meat products||9.5|
|Milk and non-cheese products||1.0|
|Cheeses with lower protein content||8.0|
|Cheeses with higher protein content||23.6|
Essentially, commonly perceived acidic food like tomato products (a vegetable) actually have a alkalizing effect on the body after digestion. The same switch goes for lemons and other acidic fruits. They start out as acidic, but after digestion, have an alkalizing effect.
What does conventional wisdom have to say about acidic foods and acid reflux?
Okay so picture yourself sitting down to meal of veal parmesan at a fancy Italian restaurant. You have a glass of red wine with your plate of battered and fried veal topped with globs of marinara sauce, parmesan cheese, and garlic, over a large plate of handmade wheat pasta.
Yum! (or, Ouch?)
In this scenario, there are a number of reasons why one may experience acid reflux. I won’t even get into those reasons in this article, although I’m sure you’re counting them in your head right now! What I’m getting at is that it’s highly likely this meal will provoke acid reflux.
If I logically think this through, without reading any of the scientific literature, I presume that the acidic marinara sauce causes irritation to the esophagus and the stomach, provoking acid reflux. And if I make that presumption, then all acidic foods coming into contact with a damaged surface area are going to hurt/sting/irritate.
But are acidic foods actually the CAUSE acid reflux?
What does the scientific literature have to say about acidic foods and acid reflux?
I found this fantastic review paper titled, “Are Lifestyle Measures Effective in Patients With Gastroesophageal Reflux Disease?: An Evidence Based Approach.” While it was published in 2006 and is slightly outdated, it nicely summarizes the research on various diet and lifestyle factors on those with acid reflux/GERD.
Here are some of the findings:
- A questionnaire of ~400 GERD patients found that 72% reported increased heartburn after eating orange or grapefruit juice
- Price et al found that acid-sensitive patients were sensitive to an infusion of orange juice even when the juice’s pH was adjusted to 7 (neutral)
- As of 2006, no studies assessed the effect of avoidance of citrus on GERD
- 2 large epidemiologic studies found no association between coffee drinking and GERD
- A Norway survey found a negative association between coffee and GERD incidence
- Salmon et al noted that patients may have GERD with coffee consumption due to the fact that coffee is frequently consumed after meals
- Different coffee preparations/processing methods change the impact on GERD
- As of 2006, there was insufficient evidence to show the effect of coffee on GERD
Consuming acidic foods does lower the pH of the stomach. But, is that a bad thing? Remember, the optimal pH range of the stomach is ~2.0 (highly acidic).
Rating- Not true at all.
Acidic foods do not CAUSE acid reflux.
However, acidic foods may irritate or trigger the symptoms of GERD/acid reflux, but they are not the reason you have this condition in the first place.
If your esophagus or stomach lining is damaged (ulcered), consider avoiding acidic foods for a period of time so that healing may occur. However, not everyone with acid reflux is required to avoid acidic foods. It is important to find the foods that work best for your body. Remember, there are many reasons why acid reflux may occur and to learn more check out this article.
- Schwalfenberg, Gerry K. “The Alkaline Diet: Is There Evidence That an Alkaline pH Diet Benefits Health?” Journal of Environmental and Public Health 2012 (2012): 727630. PMC. Web. 14 Feb. 2017.
- Remer, Thomas & Manz, Friedrich. “Potential Renal Acid Load of Foods and its Influence on Urine pH.” Journal of the American Dietetic Association (1995): 95;7. Web. 14 Feb. 2017.
- Kaltenbach T, Crocket S, Gerson L. “Are Lifestyle Measures Effective in Patients With Gastroesophageal Reflux Disease?” Arch Intern Med. (2006);166:965-971.
- Feldman M, Barnett C. Relationships between the acidity and osmolality of popular beverages and reported postprandial heartburn.Gastroenterology. (1995);108:125-131.
- Price SF, Smithson KW, Castell DO. Food sensitivity in reflux esophagitis. Gastroenterology. 1978;75:240-243.
- Wang JH, Luo JY, Dong L, Gong J, Tong M. Epidemiology of gastroesophageal reflux disease: a general population-based study in Xi’an of Northwest China. World J Gastroenterol. 2004; 10:1647-1651.
- Stanghellini V. Relationship between upper gastrointestinal symptoms and lifestyle, psychosocial factors and comorbidity in the general population: results from the Domestic/International Gastroenterology Surveillance Study (DIGEST). Scand J Gastroenterol Suppl. 1999;231:29- 37.
- de Bortoli, N., Martinucci, I., Savarino, E., Franchi, R., Bertani, L., Russo, S., Ceccarelli, L., Costa, F., Bellini, M., Blandizzi, C., Savarino, V. and Marchi, S. (2016), Lower pH values of weakly acidic refluxes as determinants of heartburn perception in gastroesophageal reflux disease patients with normal esophageal acid exposure. Dis Esophagus, 29: 3–9. doi:10.1111/dote.12284