Red 40 and other dyes may worsen the symptoms of attention deficit hyperactivity disorder (ADHD) in some, but more research is needed.

Researchers have extensively looked at the connection between diet and ADHD. Although data suggest that food dyes increase ADHD symptoms, they only seem to do so by a small amount. However, some children may be more sensitive to their effects than others.

Keep reading to learn about what red dye 40 is, how to find it on food labels, and how it can affect children with ADHD.

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Red dye 40 is a commonly used synthetic food dye made from petroleum.

It is one of nine certified color additives that the Food and Drug Administration (FDA) has approved for use in food and beverages. Manufacturers use synthetic color additives more often than natural options because they provide a more uniform color, do not add unwanted flavors, and are generally cheaper.

Food manufacturers can only use synthetic additives that the FDA has certified. Natural color additives, which are pigments from vegetables, minerals, and animals, are exempt from certification. However, the FDA must still approve them for use.

Red dye 40 is one of the most commonly used color additives. It is present in many foods and beverages, including:

  • energy and sports drinks
  • soda
  • protein powders
  • cereals
  • dairy products
  • gelatins
  • candy
  • chewing gum
  • confections

A person can identify whether a food or beverage contains red dye 40 by reading the ingredients list. Although manufacturers are not required to disclose the amount of a listed ingredient present in the product, they must list the ingredients by weight.

The ingredients labels on packaged foods and drinks may sometimes list red dye 40 by one of its other names, which include:

  • Allura Red AC
  • Red 40
  • Red 40 Lake
  • FD&C Red no. 40 Aluminum Lake
  • FD&C Red no. 40
  • E129
  • CI Food Red 17
  • INS no. 129

Research in both animals and humans has shown synthetic color additives such as red dye 40 to have links to ADHD symptoms and other neurobehavioral conditions.

In 2011, the FDA said that synthetic color additives had no adverse effects. However, research has since shown that they can cause ADHD symptoms and that some children are particularly sensitive to their effects.

According to a 2021 report from the state of California, research does indicate that children who consume synthetic food dyes, including red dye 40, can experience hyperactivity and other neurobehavioral issues.

Experts believe that red dye 40 and other synthetic color additives may cause behavioral changes due to:

  • a depletion of minerals that play a role in growth and development, including zinc and iron
  • chemical changes in the brain
  • hypersensitivity, which causes allergic reactions such as inflammation

Many studies on synthetic color additives look at red dye 40. Although the data vary, the majority of studies report at least some connection between color additives and ADHD symptoms.

Sensitivity to food dyes varies from one person to another, but most research has focused on children. Adverse effects can occur in children with and without preexisting behavioral conditions, such as ADHD.

Hyperactivity symptoms can include:

  • constant fidgeting
  • an inability to concentrate
  • being unable to sit still
  • excessive movement
  • an inability to wait their turn
  • interrupting conversations
  • little or no sense of danger

In adults, hyperactivity symptoms may also include restlessness and excessive talking.

Research indicates that hyperactivity in some children may increase due to exposure to synthetic food dyes, including red dye 40.

People often assume that sugar consumption, especially in children, can lead to an increase in ADHD symptoms, such as hyperactivity and inattention.

However, there are mixed study findings on whether sugar and ADHD are related.

According to a 2019 study in the Journal of Affective Disorders, there is some evidence that a diet high in refined sugar and saturated fat increases the risk of ADHD. However, the authors say that the current evidence, which relies primarily on observational studies, is weak and that more research is necessary.

A 2020 study in Complementary Therapies in Medicine suggests that there may be a relationship between sugar consumption and ADHD symptoms. However, another 2019 study found that there was no link between sucrose, a type of sugar, and ADHD incidence in children.

Although there is a need for more studies to determine the effects of sugar on ADHD symptoms, most research suggests that there is a link between food dyes and hyperactivity. This is especially true of the widely studied food dyes, including red no. 3, red dye 40, and yellow no. 5.

Red dye 40 is a synthetic food dye made from petroleum. Research has shown that it is linked to certain ADHD symptoms, such as hyperactivity, and may also cause other neurobehavioral effects in children.

People can check for red dye 40 on food labels if they wish to limit their intake. It is important to note that it may go by other names, including Allura Red AC, Red 40, Red 40 Lake, FD&C Red no. 40 Aluminium Lake, and FD&C Red no. 40.