Will Lemon Juice Lower pH? The Surprising Truth

October 19, 2025 •

4 min read

With a pH level between 2 and 3, lemon juice is highly acidic. While this immediately suggests that lemon juice will lower pH, the outcome depends entirely on what you're adding it to and the complex chemical reactions that follow.

Quick Summary

Lemon juice lowers the pH of non-buffered solutions like water and soil due to its high citric acid content. However, its effect on the tightly regulated pH of the human body is negligible, despite common alkaline diet claims.

Key Points

Initial Acidity: Lemon juice is highly acidic, with a pH of 2 to 3, due to its citric acid content.
Effect on Non-Buffered Solutions: It will effectively lower the pH of water or soil when added, as there are no buffering agents to resist the change.
No Significant Effect on Blood pH: The human body has strong buffering systems to keep blood pH stable, so consuming lemon juice does not change overall body acidity.
Alkalizing Effect on Urine: The body metabolizes lemon juice into alkaline byproducts that are excreted in urine, which can make the urine more alkaline.
Gardening Applications: Diluted lemon juice is a natural way to acidify soil for plants that prefer a lower pH, but it must be used carefully to avoid root damage.
Oral Health Risk: The high acidity can erode tooth enamel, so it's important to consume it sparingly or dilute it significantly.
Context is Key: Whether lemon juice lowers pH depends on the system it is introduced to, highlighting the difference between a direct chemical reaction and a biological metabolic process.

Understanding the pH Scale and Acidity

To comprehend how lemon juice affects pH, one must first understand the pH scale itself. The scale measures the concentration of hydrogen ions ($H^+$) in a solution, ranging from 0 (most acidic) to 14 (most alkaline or basic), with 7 being neutral. A lower pH indicates a higher concentration of $H^+$ ions. Lemon juice, with its high citric acid content, is a potent source of these ions, which is why it tastes sour and is highly acidic before any chemical reactions take place.

The Direct Effect: Mixing Lemon Juice with Water

When you add lemon juice to a neutral liquid like distilled water, the result is straightforward: the pH will drop. A few drops of lemon juice can significantly lower the pH of a glass of water, making it more acidic. This is a simple chemical reaction where the citric acid in the lemon juice releases hydrogen ions into the water. This principle is commonly used in applications such as hydroponics, where growers use a small amount of lemon juice to adjust the water's pH for optimal plant growth. However, the exact change in pH depends on the initial pH of the water and its buffering capacity—a key distinction that explains why results vary widely.

The Effect on Soil pH

For gardeners looking to acidify their soil, lemon juice can be a quick, natural solution. Many plants, such as blueberries and azaleas, thrive in acidic conditions. By diluting lemon juice with water and adding it to the soil, you can effectively lower the soil's pH over time. However, this method requires caution and careful measurement. Overuse can damage plant roots, and for long-term pH management, more stable solutions like soil acidifiers or organic matter are often recommended.

How to apply lemon juice to soil:
- Dilute 1 teaspoon of lemon juice per liter of water.
- Apply this mixture every two weeks.
- Always test the soil's pH beforehand to avoid over-acidifying.
- Consider the long-term impacts versus commercial soil acidifiers.

The Effect on the Human Body's pH

Here is where the scientific reality diverges from popular belief. Contrary to the claims of the 'Alkaline Diet' movement, consuming lemon juice does not significantly alter the pH of your blood. The human body has powerful and tightly-regulated buffering systems, primarily involving the kidneys and lungs, to maintain blood pH within a very narrow, healthy range of 7.35 to 7.45. If your blood pH were to shift dramatically due to diet, it would indicate a serious, life-threatening medical condition, not a diet-related issue.

However, what does change is the pH of your urine. When your body metabolizes the citric acid in lemon juice, it produces alkaline byproducts that are then excreted, making the urine more alkaline. This is the basis for the misconception, as test strips measuring urine pH will show a shift, which is then misinterpreted as a change in overall body pH. This urinary effect is why some people find relief from specific conditions, such as preventing certain kidney stones, but it does not mean your entire body is 'alkalized'.

Comparison: Lemon Juice vs. Commercial pH Adjusters


Feature	Lemon Juice	Commercial pH Adjusters
Cost	Very low, often using common kitchen ingredients.	Varies, but generally higher.
Effectiveness	Highly effective for small-scale, immediate pH adjustments.	Consistent and reliable for larger or more precise applications.
Control	Requires careful measurement and testing due to variable concentration.	Formulated for predictable results, often with clear dosage instructions.
Sustainability	Natural and biodegradable, but over-application can be wasteful.	Some products may contain synthetic chemicals, but options are available.
Application	Best for small household projects, like watering a few houseplants.	Ideal for commercial agriculture, hydroponics, or large gardens.
Side Effects	Potential root damage in plants if overused; corrosive to tooth enamel.	Minimal side effects if used as directed; potential chemical runoff if misused.

Conclusion

In summary, the answer to "will lemon juice lower pH?" is a definitive yes, but with important context. In external solutions like water or soil, the acidic nature of lemon juice will effectively lower the pH. For applications like hydroponics and gardening, it provides a natural and cost-effective way to achieve a lower pH, but it must be used with caution due to its variable concentration and potential for overuse. However, when it comes to the human body, the myth that lemon juice can alter overall blood pH is scientifically unfounded. Your body's robust buffering systems ensure that blood pH remains stable, regardless of what you consume. The mild alkalizing effect is limited to urine, and while it may offer some benefits, it is not the systemic body-alkalizing solution that is sometimes portrayed. Ultimately, understanding the science behind pH is key to using lemon juice effectively and avoiding common misconceptions.

Explore more about the complex buffering systems that maintain human blood pH on the National Institutes of Health website.

Frequently Asked Questions

No, drinking lemon water will not make your body more alkaline. Your body has very efficient buffering systems to maintain a stable blood pH between 7.35 and 7.45. While the metabolites of lemon juice can make your urine more alkaline, your blood pH remains unaffected.

The amount varies depending on the initial pH and buffering capacity of your water. For example, some gardeners find that a teaspoon of lemon juice per quart of water can lower the pH significantly, but testing is always recommended for accuracy.

Lemon juice can be used for short-term, mild adjustments to soil pH. For consistent, long-term soil acidification, more stable and professional products or incorporating organic matter are better options to avoid potential root damage from over-application.

This effect is debated and not supported by conclusive research. It's possible that lemon juice may stimulate digestive enzymes or have a placebo effect. However, due to its acidity, it can also worsen symptoms for others.

Yes, regular consumption of undiluted or lightly diluted lemon juice can erode tooth enamel over time due to its high citric acid content. Using a straw and rinsing your mouth with plain water afterward can help minimize this risk.

For accurate measurements, it is best to use a pH testing kit or a digital pH meter. This is especially important for applications like gardening or hydroponics where precise pH levels are critical.

The PRAL score is a method used to estimate the acid or alkaline load a food places on the kidneys after metabolism. Lemon juice has a negative PRAL score, indicating it produces alkaline byproducts, which is why it's sometimes incorrectly called 'alkalizing'.