What foods can fluorine be found in?

December 21, 2025 •

3 min read

While most people associate fluorine primarily with dental health products, the mineral, in its ionic form as fluoride, is found naturally in a wide array of foods and water. This occurs because fluorine is the 13th most abundant element on Earth and is present in the soil and water where these food items grow or are raised. The concentration of this element can vary significantly depending on the food's origin and how it was processed.

Quick Summary

Fluoride is found naturally in many foods, with higher concentrations in tea, seafood, grapes, and potatoes. Its presence is influenced by the water and soil conditions where the food was sourced. This article outlines key dietary sources of fluoride and contextualizes its role in overall health.

Key Points

Fluorine vs. Fluoride: Fluorine is the elemental gas ($F$), while fluoride ($F^-$) is the stable ion found in food and water.
Primary Dietary Sources: Tea, seafood (especially bony fish like sardines), grapes, raisins, and potatoes are some of the most concentrated food sources of fluoride.
Water's Influence: The fluoride content of water, whether natural or supplemented, significantly impacts the total intake from beverages and cooked foods.
Risk of Overexposure: Excessive, chronic fluoride intake can cause dental or skeletal fluorosis, characterized by tooth discoloration and bone issues.
Balanced Intake is Key: For optimal health, it is important to be aware of all fluoride sources to ensure a balanced and appropriate intake, especially for children.

Understanding Fluorine vs. Fluoride

Before diving into specific food sources, it's essential to clarify the distinction between fluorine and fluoride. Fluorine ($F$) is a highly reactive, pale yellow-green gas and is the elemental form of the mineral. Fluoride ($F^-$) is the stable, negatively charged ion of fluorine that is commonly found in water, food, and dental products. In a dietary context, when we refer to the presence of fluorine, we are discussing the fluoride ion contained within the food.

Top Food Sources Containing Fluorine (as Fluoride)

Tea

Black and green teas are among the most significant dietary sources of naturally occurring fluoride. The tea plant, Camellia sinensis, is known for its ability to accumulate fluoride from the soil. The fluoride is released into the brew during steeping, with concentrations varying based on the type of tea (black tea often has higher levels), brewing time, and the fluoride content of the water used.

Seafood

Seafood is another notable source, especially varieties that are eaten with the bones or shells. Marine animals like canned salmon, sardines, shrimp, and crab have higher fluoride levels due to the mineral accumulating in their tissues. A study on Indian seafood showed that sea fishes accumulate higher fluoride levels than river fish, suggesting that fluoride concentration is linked to the aquatic environment.

Fruits

Certain fruits contain naturally occurring fluoride. Grapes and raisins are particularly good sources, with raisins having a high concentration due to the drying process. Other fruits such as apples, bananas, and strawberries also contain smaller amounts.

Vegetables

Some vegetables can also contribute to fluoride intake. Potatoes, especially baked russet potatoes, and spinach contain significant amounts. The final fluoride content can be influenced by the soil composition and the water used during cooking.

Grains and Processed Foods

Items like cooked oatmeal and white rice can contain fluoride, especially when prepared with fluoridated water. Infant foods, depending on the ingredients and processing, can also contain varying fluoride levels.

The Role of Water and Food Processing

Water is often the largest source of dietary fluoride intake, particularly in areas with water fluoridation. The water used in cooking and food processing can significantly impact the final fluoride content of a dish. For instance, brewing coffee or tea with fluoridated tap water will increase the fluoride content of the beverage. This is an important factor to consider when evaluating total dietary fluoride intake.

Comparison Table: High vs. Low Fluoride Foods


Food Category	Foods with High Fluoride Levels	Foods with Low Fluoride Levels
Beverages	Black Tea, Green Tea, Wine	Milk, Juice, Herbal Tea
Seafood	Canned Sardines, Canned Salmon (with bones), Shrimp, Crab	Most Fish Fillets
Fruits	Grapes, Raisins	Berries, Citrus Fruits, Melons
Vegetables	Potatoes, Spinach, Beets	Lettuce, Carrots, Eggs
Grains	Almonds, Walnuts, Rice, Bread, Oatmeal	Corn, Legumes

Potential for Overexposure and Health Considerations

While fluoride is beneficial for dental health in small doses, excessive intake over prolonged periods can be harmful, leading to dental or skeletal fluorosis. Dental fluorosis causes discoloration of tooth enamel, typically seen as white or brown spots, and occurs during tooth development. Skeletal fluorosis, a more severe condition, can cause joint pain and stiffness and is associated with chronically high intake. For most individuals in regions with optimally fluoridated water, dietary intake alone is unlikely to cause fluorosis. However, in areas with naturally high levels of fluoride in the water supply, total intake from all sources must be monitored.

Conclusion: Finding the Right Balance

Fluorine, in its ionic form as fluoride, is a naturally occurring mineral found in a range of foods and is particularly concentrated in tea, seafood, and some fruits and vegetables. While beneficial for oral health in optimal amounts, balancing intake from all sources—including fluoridated water, toothpaste, and food—is essential to prevent overexposure. By being aware of dietary sources, individuals can make informed choices to support their health without risking the negative effects of excessive fluoride intake. For more in-depth information on dietary minerals, consult reliable nutritional resources like those found on the Harvard T.H. Chan School of Public Health website.

Frequently Asked Questions

Yes, both food and toothpaste contain the same active fluoride ion ($F^-$). The key difference is the concentration and application method; toothpaste provides a high, topical dose directly to the teeth, whereas food provides a lower, systemic dose through digestion.

Black and green teas are particularly high in fluoride because the tea plant accumulates the mineral from the soil. The fluoride content is also influenced by brewing time and the water used. Herbal teas, however, generally have negligible amounts.

Fluoride accumulates in the bodies of marine life from the seawater they inhabit. This is especially true for shellfish and fish that are consumed with their bones, such as canned sardines or salmon, leading to higher concentrations in these products.

While it is possible, it is rare to get excessive fluoride from diet alone in most regions. The risk of overexposure is much higher in areas with naturally high fluoride levels in the drinking water, especially when combined with high dietary intake. Total intake from all sources is the key factor.

Yes, cooking can affect fluoride content, primarily based on the water used. If a food is cooked in fluoridated water, it will absorb some of that fluoride. This is particularly relevant for foods like rice, pasta, and potatoes.

Yes, raisins contain a concentrated amount of fluoride due to the dehydration process. While a handful is not a concern, it is worth noting when monitoring total fluoride intake, especially for children, as they are also high in sugar.

According to the American Dental Association, reconstituted liquid or powdered infant formulas mixed with fluoridated water can lead to overexposure in infants. To mitigate this risk, it is recommended to use prepared formula or mix powdered formula with fluoride-free water.