Quick Answer
Common low stomach acid symptoms include heaviness after meals, bloating and belching soon after eating, heartburn, undigested food in your stool, and low iron or B12 over time. The most common causes are H. pylori infection, chronic gastritis and long-term acid-blocking medication. Because low and high stomach acid can feel alike, it's worth testing with a practitioner before trying to raise it.
A Nutritionist's Take
"Stomach acid is the first thing I look at for digestive complaints. Low and high can feel almost the same, so test, don't guess."
— Jordan Dorn, Certified Nutritionist
When most people feel heartburn or heaviness after a meal, they assume they have too much stomach acid and reach for an antacid. Sometimes that's right. But sometimes the problem is the opposite: not enough acid to break food down properly, so it sits in the stomach, ferments and pushes back up.
Stomach acid is the first thing I look at when someone tells me about digestive complaints. Early on, I talked with so many young women in LA who had been eating low-protein, high-sugar diets for years and ended up with low stomach acid.
In this article, I'll cover what stomach acid actually does, the most common low stomach acid symptoms, what causes it (including one myth about aging), how it's tested, and the natural steps that can help, with the evidence for each labeled honestly.
In this article 9 sections
What Stomach Acid Actually Does
Your stomach makes hydrochloric acid (HCl) to keep its contents very acidic. That acid has several jobs, and when it runs low, all of them suffer:
Breaks down protein. Acid activates pepsin, the enzyme that starts protein digestion.
Frees nutrients. Acid helps release vitamin B12 from food and supports absorption of minerals like iron.
Defends against microbes. It's your first line of defense against bacteria and other organisms you swallow.
Kicks off the rest of digestion. Acidic food leaving the stomach signals the pancreas and gallbladder to release enzymes and bile.
That last point is why low stomach acid rarely stays a stomach problem. If the first step of digestion is weak, everything downstream has to work harder.
9 Low Stomach Acid Symptoms
These symptoms are associated with low stomach acid (hypochlorhydria), but none of them is specific to it. They overlap with many other digestive issues, which is exactly why testing matters.
Heaviness after meals, especially protein-rich ones, as if food is just sitting there.
Bloating soon after eating, within the first hour.
Frequent belching after meals.
Heartburn or reflux. This surprises people. Some integrative practitioners believe poorly digested food that sits too long can push acid back up, but this idea isn't well studied, and true excess acid causes heartburn too.
Undigested food in your stool.
Nausea when taking supplements or after heavy meals.
Low iron or B12 on blood work despite a decent diet.
Fatigue, often linked to those nutrient gaps.
Ongoing gut issues like SIBO, since acid is part of what keeps bacteria from building up in the small intestine.
Low vs. High Stomach Acid: Why They Feel the Same
This is the part most people get wrong. Low and high stomach acid can both show up as heaviness, bloating, belching and heartburn. You can't reliably tell them apart by how you feel, and guessing wrong matters: taking something to raise acid when your stomach lining is already irritated can make things worse, and taking antacids when acid is already low can make digestion worse.
That's why I always say test, don't guess. Self-diagnosing from a social media video is one of the most common mistakes I see with gut issues. If you have reflux, our guides to heartburn vs. acid reflux and the best foods for acid reflux cover the high-acid side.
What Causes Low Stomach Acid?
H. pylori and chronic gastritis
H. pylori is a common stomach bacterium that can inflame the stomach lining over time. Long-standing inflammation, called atrophic gastritis, damages the cells that make acid. A comprehensive stool test like a GI-MAP can screen for H. pylori, along with other imbalances that often show up alongside it.
Long-term acid-blocking medication
Proton pump inhibitors (PPIs) and H2 blockers work by lowering acid, and long-term use has measurable effects. In a study of more than 25,000 people with B12 deficiency, those who had taken PPIs for two years or more had a 65% higher risk of deficiency [3]. A meta-analysis of 19 studies also found PPIs moderately increased the risk of SIBO [2]. These medications are important for many people, so never stop them on your own. Talk with your doctor about whether you still need them.
Stress and eating on the go
Acid production starts before food even reaches your stomach, when you see, smell and anticipate a meal. That only happens well in rest-and-digest mode. Eating a burrito while driving and talking on the phone puts you in fight or flight, and digestion is the last thing your body prioritizes. Stress is one of the most direct drivers of poor gut health I know of.
Diet
Long stretches of low-protein, high-sugar eating are a pattern I've seen come up again and again with low stomach acid. And while I'm not into strict food combining, a big, sugary dessert right after a high-protein meal doesn't help your digestion.
What about aging?
You'll often read that stomach acid simply declines with age. The research is more interesting than that. In a study of 206 healthy adults aged 18 to 98, acid output was about 30% lower in people over 65, but after accounting for gastritis and H. pylori, age itself had no independent effect [1]. In other words, it's usually the conditions that become more common with age, not age itself.
How to Test for Low Stomach Acid
Heidelberg test. You swallow a small capsule that measures stomach pH directly. It's the most direct test, though not widely available.
H. pylori testing. Breath, stool or blood tests can check for infection, a major cause of low acid.
Blood work. Low B12, iron or ferritin can be indirect clues.
The baking soda test. You drink baking soda in water and time how long until you burp. It's popular online, but it hasn't been validated, and results depend on too many variables to be reliable.
Betaine HCl challenge. Some practitioners use gradually increasing doses of betaine HCl with meals to gauge acid levels. It's not a validated test either, and it isn't safe for everyone, so only do it with professional guidance.
How to Increase Stomach Acid Naturally
1. Eat in rest-and-digest mode
Sit down for meals. Take a few breaths before you eat. One of my favorite authors, Thich Nhat Hanh, wrote a small book called How to Eat about being present with your food, and it's one of the most practical things you can do for digestion. When you feel anxious, a walk without your phone before you eat helps too.
2. Get enough protein and ease off sugar
Build meals around quality protein, make half your plate vegetables, and cut back on constant high-glycemic foods like high-fructose corn syrup, added sugar and fruit-heavy smoothies.
3. Use bitters
Bitter tastes have traditionally been used to get digestion going, including acid and bile flow. I picked up the habit of taking bitters after meals the Italian way from my godmother in Tuscany. Bitter greens like dandelion, arugula and radicchio work too, and as people cut back on sweets, their palate usually shifts toward bitter foods anyway. Formal research on bitters is limited, so think of them as gentle support. More in our guide to bitter herbs and how they work.
4. Chew thoroughly and slow down
Digestion takes time, hours for some foods. People on the go take a handful of vitamins, eat fast and assume they're absorbing everything. Chewing well means less work for your stomach and less undigested food moving downstream.
5. Apple Cider Vinegar, Diluted
I'm a huge fan of apple cider vinegar. It fits right into my whole-food approach to gut health and digestion, and I find it great for helping with stomach acid. To be clear about the evidence, studies haven't directly measured whether it raises your own stomach acid, so that part rests on experience more than research.
Where the research is stronger is blood sugar. In a small study, people with insulin resistance who drank diluted vinegar before a high-carb meal had 34% better insulin sensitivity after the meal [5]. It's also a pretty effective antifungal: in lab studies, apple cider vinegar inhibited Candida albicans [6]. Lab results don't always translate to the body, but it's one more reason I like it.
Two things matter. First, quality: I recommend getting raw, unfiltered apple cider vinegar from a farmer's market rather than a mass-market grocery brand. Second, always dilute it in water. It's very, very strong, and straight it can definitely give you a burn, and it's hard on tooth enamel. If you take blood sugar medication, check with your doctor first, since vinegar can add to its effect. Our article on apple cider vinegar for acid reflux covers more.
6. Support digestion with enzymes
Enzymes don't raise stomach acid, but they help with the next steps of breaking food down, which takes pressure off a struggling system. I'm a huge fan of digestive enzymes, especially for people who feel heavy after meals. Our Digestive Enzyme Complex is a vegan blend of 14 enzymes taken with meals.†
What Customers Report
As of October 2026, our Digestive Enzyme Complex has 101 customer reviews averaging 4.88 out of 5: 92 five-star, 6 four-star, 3 three-star, and none lower. More than half mention digestion. Not everyone noticed a big change: one three-star reviewer said their gut felt a little better after meals but the results weren't dramatic. Results vary.
7. Hydrate with minerals
Drink good spring or mineral-rich water and get electrolytes from whole foods like quality greens and fruit. Many people add trace minerals to their water; our Fulvic Acid & Trace Ocean Minerals provides 70+ ionic minerals in a liquid form.†
8. Betaine HCl: Effective, but Diet First
Betaine HCl is a supplement form of hydrochloric acid, and I think it can be a very effective supplement for people who need it. I don't take it myself, but I've heard great results from people who have. Still, I'd rather get there with diet first: a healthy, balanced diet with enough protein, plus bitters to get digestion going. I'm a big fan of trying things naturally before you turn to a supplement, but if you need it, betaine HCl is a very effective way to give your body the hydrochloric acid it needs for digestion.
The research is still thin. In a small pilot study of six healthy volunteers whose acid had been lowered with a PPI, a single dose brought stomach pH from about 5.2 down to 0.6 within 30 minutes, with the effect lasting a little over an hour [4]. That shows it can temporarily acidify the stomach, but it's a tiny study and not evidence that it fixes low acid long term.
Betaine HCl isn't safe for everyone. Avoid it if you have ulcers, gastritis or active heartburn, or if you take NSAIDs, steroids or other medications that irritate the stomach lining. This is one to use only with a practitioner.
Low Stomach Acid, SIBO and Bloating
Because acid helps keep bacteria out of the small intestine, low stomach acid and SIBO often travel together. In my experience, it's rarely just one thing: a fuller workup often shows several issues at once. If bloating is your main complaint, start with our guide to why you might always be bloated. If an overgrowth is confirmed, our guide to getting rid of SIBO naturally walks through a full approach, and herbal formulas like our SIBO-Clear Tonic are made for that phase, ideally with a practitioner's guidance.†
When to See a Doctor
See a doctor promptly if you have black or bloody stools, vomit that looks like coffee grounds, trouble swallowing, unexplained weight loss, signs of anemia, heartburn more than twice a week for several weeks, or new digestive symptoms after age 50. Don't stop or change any prescribed acid-blocking medication without talking to your doctor first.
The Bottom Line
Low stomach acid is common, easy to miss and easy to confuse with too much acid. Don't take your digestion for granted, and don't guess. Get tested, look at the usual causes like H. pylori and long-term acid blockers, and support the basics: eat calmly, get enough protein, cut back on sugar, use bitters and give your digestion the time it needs.
References
Feldman M, et al. Effects of aging and gastritis on gastric acid and pepsin secretion in humans: a prospective study. Gastroenterology. 1996;110(4):1043–1052. PMID 8612992
Su T, et al. Meta-analysis: proton pump inhibitors moderately increase the risk of small intestinal bacterial overgrowth. J Gastroenterol. 2018;53(1):27–36. PMID 28770351
Lam JR, et al. Proton pump inhibitor and histamine 2 receptor antagonist use and vitamin B12 deficiency. JAMA. 2013;310(22):2435–2442. PMID 24327038
Yago MR, et al. Gastric reacidification with betaine HCl in healthy volunteers with rabeprazole-induced hypochlorhydria. Mol Pharm. 2013;10(11):4032–4037. PMID 23980906
Johnston CS, Kim CM, Buller AJ. Vinegar improves insulin sensitivity to a high-carbohydrate meal in subjects with insulin resistance or type 2 diabetes. Diabetes Care. 2004;27(1):281–282. PMID 14694010
Yagnik D, Serafin V, Shah AJ. Antimicrobial activity of apple cider vinegar against Escherichia coli, Staphylococcus aureus and Candida albicans; downregulating cytokine and microbial protein expression. Sci Rep. 2018;8. PMC5788933
