Acidic Foods and Heartburn: What’s the Connection?


 Posted by Susan Bowerman, M.S., RD, CSSD, CSOWM, FAND – Senior Director, Worldwide Nutrition Education and Training  0 Comment

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Sit upright for a while after eating.

Heartburn is something that many people get on occasion, and what you eat plays a role. But are high acid foods really the culprit?

Occasional heartburn is one of those digestive upsets that might hit you from time to time. Most of the time you can probably figure out what triggered it. Usually it’s simply a matter of over-indulgence in a heavy meal—especially one eaten too close to bedtime. Other times, extra helpings of rich food topped off with too much wine or coffee are to blame.

Since heartburn is sometimes referred to as acid indigestion, lots of people assume that highly acidic foods are to blame.

Acidic Foods and Stomach Acid

Many people tell me that they stay away from highly acidic foods like tomatoes and citrus, because “they just give me too much stomach acid.” Logical as it may sound, high acid foods aren’t really the problem.

That’s because the acid in your stomach doesn’t come from the foods that you eat. Not only that, your stomach acid is also a lot stronger than anything you’d ever put in your mouth.

How Acidic is Your Stomach, Anyway?

Acidity is expressed in terms of pH, a scale with numbers that range from 0 to 14. The lower the pH value, the more acidic a substance is. Most healthy people have digestive fluid with a very low pH, usually between 1.5 and 2. Believe it or not, it contains hydrochloric acid (also found in certain household cleaners). That’s 50-100 times more acidic than pure lemon juice!

You need that acidity, by the way. It helps get the digestive process started, and it also helps to wipe out any ‘bugs’ in your food that could make you sick.

The foods you eat aren’t more acidic than the natural gastric juices in your stomach. Oranges have a pH of 3.5 to 4, and the pH of tomatoes runs between 4.5 and 5. You might say black coffee feels acidic, but it actually has a pH close to 5—about the same as a banana. And the pH of cider vinegar is the same as the pH of fresh blueberries, about 3.1.

So, eating these everyday “acidic” foods can’t really make your stomach any more acidic than it already is. Not only that, eating a meal doesn’t cause the acid level in your stomach to go up. It actually goes down quite a bit. In fact, soon after you start eating a meal, the pH in your stomach rises to about 5.

If the digestive juices in your stomach are more acidic than any foods you’re likely to put in it, then why do so many people complain about the effects of some of these high acid foods? In many cases, it could be that people are really experiencing heartburn. This is actually an irritation of the esophagus. It’s not in the stomach—or the heart, for that matter.

What Is Heartburn?

Heartburn is a bit like a plumbing problem in the digestive tract.

At the bottom of your esophagus, where it meets the stomach, there’s a ring of muscle called the lower esophageal sphincter, or LES. This muscle normally opens up to allow food to enter the stomach, then snaps shut to keep the stomach entrance closed.

But if this LES muscle relaxes, the acidic stomach contents can back up into the esophagus. While the lining of your stomach is well-equipped to handle the corrosive stomach acid, your esophagus isn’t and the result is the irritation we call heartburn.

Certain foods and dietary habits can encourage the LES muscle to slacken a little after eating. If you eat a very large meal, or lie down right after eating, it puts upward pressure on the LES muscle which can make it more difficult to stay completely closed.

Certain acidic foods, like tomatoes, citrus and coffee, can contribute to heartburn. But not because of their acidity.

Instead, these foods (as well as chocolate, garlic, onions and alcoholic beverages) actually cause the LES muscle to relax a bit. This leads to a bit of backflow into the esophagus, causing a burning sensation just behind the breastbone.

Diet and Heartburn

Even though acidic foods don’t increase the acidity of the stomach, you may still want to cut back on them when you experience occasional bout of heartburn (no more than once or twice a month). Since the esophagus might be a little sensitive, you might be more comfortable if you steer away from irritating foods. Not just those that are acidic, but spicy foods, alcohol and coffee, too.

To avoid heartburn in the future, it helps to look at the root of the problem and the steps you can take to keep stomach acid where it belongs—in your stomach. Eating smaller meals and losing weight helps, because big bellies put upward pressure on the LES muscle and cause the system to back up.

Keeping meals low in fat can also help, since fatty meals tend to sit in the stomach longer than lower fat meals do. It also helps stay upright for a few hours after eating. So, consider taking a walk after dinner instead of collapsing on the couch.

Although occasional heartburn isn’t unusual, it also isn’t something to ignore. If diet and lifestyle measures don’t help, of if you experience heartburn a couple of times a week or more, be sure to see your doctor.

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Susan is the Senior Director of Worldwide Nutrition Education and Training at Herbalife, where she is responsible for the development of nutrition education and training materials, and is one of the primary authors of the Herbalife-sponsored blog, www.discovergoodnutrition.com. She is a Registered Dietitian and holds two Board Certifications from the Academy of Nutrition and Dietetics as a Certified Specialist in Sports Dietetics, and a Certified Specialist in Obesity and Weight Management. Susan is also a Fellow of the Academy of Nutrition and Dietetics. Susan graduated with distinction in biology from the University of Colorado, and received her master’s degree in Food Science and Nutrition from Colorado State University. She then completed her dietetic internship at the University of Kansas. Susan has taught extensively and developed educational programs targeted to individuals, groups and industry in her areas of expertise, including health promotion, weight management and sports nutrition. Prior to her role at Herbalife, she was the assistant director of the UCLA Center for Human Nutrition, and has held appointments as adjunct professor in nutrition at Pepperdine University and as lecturer in nutrition in the Department of Food Science and Nutrition at Cal Poly San Luis Obispo. Susan was a consultant to the (then) Los Angeles Raiders for six seasons, and was a contributing columnist for the Los Angeles Times Health Section for two years. She is a co-author of 23 research papers, 14 book chapters, and was a co-author of two books for the public: “What Color is Your Diet?” and “The L.A. Shape Diet” by Dr. David Heber, published by Harper Collins in 2001 and 2004, respectively.