Clarifying What Foods Contain Citrin and Citrulline

December 20, 2025 •

3 min read

Many people search for what foods contain citrin, but the truth is that citrin is a protein in your body, not a compound found in food. It's a key transporter in the liver's mitochondrial membrane, and issues with this protein lead to the rare genetic condition known as citrin deficiency.

Quick Summary

This article explains the difference between the protein citrin and the amino acid citrulline, identifying food sources for the latter. It also clarifies that citrin is not a dietary nutrient and discusses the dietary preferences related to a metabolic disorder called citrin deficiency.

Key Points

Citrin vs. Citrulline: Citrin is a protein made by the body, whereas citrulline is an amino acid found in food and supplements.
Citrin is Not in Food: As a protein made within the body, citrin is not a dietary component.
Watermelon Source: Watermelon is a notable natural source of citrulline.
Citrulline's Role: Citrulline contributes to nitric oxide production, which supports blood flow and may benefit exercise and heart health.
Citrin Deficiency and Diet: People with citrin deficiency often favor high-protein and high-fat foods while avoiding carbohydrates.
Other Citrulline Sources: Foods like cucumbers, pumpkins, other melons, and chickpeas also contain citrulline.

The Crucial Difference: Citrin vs. Citrulline

There is often confusion between 'citrin' and 'citrulline' due to similar names. However, citrin is a protein produced within the body, while citrulline is an amino acid that can be found in food and supplements. Understanding this distinction is key to determining what foods relate to citrin or citrulline.

What is Citrin?

Citrin is a protein made in the liver's mitochondrial membrane from the SLC25A13 gene. It functions as a transporter for molecules essential to metabolic processes like the urea cycle and energy production. Genetic mutations affecting citrin function cause citrin deficiency, a metabolic disorder most common in East Asia. As citrin is a bodily protein, it is not present in food.

What is Citrulline?

Citrulline is a non-essential amino acid, meaning the body can produce it, but it is also found in various foods. It was first identified in watermelon, from which it gets its name. Citrulline plays a role in the urea cycle, helping remove ammonia. The body also converts citrulline into arginine and nitric oxide, which supports blood flow by widening blood vessels. Citrulline supplements are also used, often by athletes, for their potential to enhance performance.

Foods High in Citrulline

If you're seeking dietary citrulline, several fruits and vegetables contain this amino acid. Watermelon is particularly rich in citrulline, with higher amounts often found in the rind. Other members of the gourd family (Cucurbitaceae) are also good sources.

Key food sources of citrulline include:

Watermelon: The primary and most abundant source.
Cucumbers: Part of the same botanical family as watermelon.
Pumpkin: Contains citrulline.
Squash: Including varieties like zucchini.
Other Melons: Such as cantaloupe and muskmelon.
Bitter Melon: Citrulline is present, especially in the seed's covering.
Chickpeas: A legume also containing citrulline.

The Dietary Patterns of Citrin Deficiency

While citrin itself is not in food, citrin deficiency significantly impacts dietary habits. Individuals with this condition often develop specific and sometimes unusual food preferences as their bodies adapt to the metabolic challenges. These preferences include a strong liking for foods high in protein and fat, such as meats, eggs, and nuts, coupled with an avoidance of high-carbohydrate foods like rice and bread. These dietary choices are believed to be the body's way of finding alternative energy sources to bypass affected metabolic pathways. A recommended management strategy for citrin deficiency involves a low-carbohydrate, high-protein, and high-fat diet, sometimes supplemented with MCT oil. This illustrates how a condition related to a bodily protein directly influences dietary needs.

Comparing Citrin and Citrulline

A comparison between citrin and citrulline highlights their differences:


Feature	Citrin	Citrulline
Classification	Mitochondrial transporter protein	Non-essential amino acid
Source	Produced in the body by the SLC25A13 gene	Found in foods like watermelon, squash, and chickpeas
Function	Transports molecules for the urea cycle and energy production	Involved in nitric oxide production, blood flow, and ammonia removal
Connection to Disease	Deficiency causes citrin deficiency	Potential benefits for exercise and heart health
Dietary Intake	Not a dietary nutrient	Can be consumed from food and supplements

Understanding the Distinction for Health

The case of citrin and citrulline emphasizes the difference between biological components and dietary nutrients. Citrin is not obtained from food, while citrulline can be increased through consuming certain fruits and vegetables. For concerns about metabolic conditions or unusual eating patterns, consulting a healthcare professional is advisable. What seems like a simple question about food can relate to complex biological processes or conditions.

In summary, citrin is a protein made by the body and is not found in food. Citrulline, a similar-sounding amino acid, is present in foods like watermelon and cucumbers. Individuals with citrin deficiency often develop specific dietary inclinations, preferring high-fat and protein foods as a physiological adaptation. Therefore, the focus regarding dietary sources in this context should be on foods containing citrulline.

{Link: Cleveland Clinic https://health.clevelandclinic.org/citrulline-benefits}

Frequently Asked Questions

No, citrin and citrulline are distinct. Citrin is a protein produced by the body, whereas citrulline is an amino acid found in foods and supplements.

This preference arises because their bodies have difficulty processing carbohydrates for energy due to the deficiency. They naturally gravitate towards fats and proteins as alternative energy sources.

Yes, aside from watermelon, other sources of citrulline include members of the gourd family like cucumbers, pumpkins, and various melons, as well as chickpeas and nuts.

Citrulline is converted to arginine and nitric oxide, which helps dilate blood vessels and improve blood flow. It also aids in removing ammonia via the urea cycle.

Citrin is a transport protein in liver mitochondria that facilitates the movement of aspartate and glutamate, important for the urea cycle and energy production.

Citrin deficiency is typically diagnosed through genetic testing for mutations in the SLC25A13 gene. Newborn screening results showing elevated levels of certain amino acids can also indicate the condition.

Yes, citrulline is available as a dietary supplement, often as L-citrulline or citrulline malate, and is used for potential benefits related to athletic performance and heart health.