Keeping Our Food Supply Safe: the Total Diet Study

Have you ever wondered what chemicals are lurking in your food? Which pesticides are on your apples? Whether there’s arsenic in your rice? The U.S. Food and Drug Administration (FDA) has. Through a program called the Total Diet Study, the FDA monitors approximately 280 foods that are representative of the American diet. Each food undergoes extensive testing to figure out what’s in it. This yields a big picture view of just what nutrients and chemicals are in the U.S. food supply.

What is the American diet?

In order to understand what the American population is exposed to in their diet, we have to understand what’s in each of the components that make up the diet. This means that we must understand apples, bananas, carrots, bread, meat, and even chocolate cake. Researchers at FDA have come up with a list of approximately 280 foods that, as a group, are representative of a “typical” American diet. What’s “typical,” you ask? Researchers are working on that question too. They use data from national surveys to figure out what foods people eat. This list changes over time as the American diet evolves. Foods that become more popular over time, like quinoa, are added to the list. Other foods (think things your grandparents ate that you wouldn’t touch today) are gradually eliminated. FDA revises the list regularly to keep up with changing food preferences.

How does it work?

The U.S. is a big, diverse place. In order to make sure that the entire country gets represented during the course of sampling, the FDA has divided the country into six regions. Each month, FDA investigators collect a huge list of foods from three cities within a region. They then send the foods to a central laboratory for testing. The next month, FDA investigators will collect foods from (three cities in) a different region, and so on. All in all, each region undergoes a monthly collection twice a year (6 regions x 2 collections per year = 12 collections, or one monthly). These two collections per region per year take place in different seasons. And while the regions do not change, the collection cities within a region do.

Investigators generally collect fresh foods like fruits and vegetables during the monthly collections. Shelf-stable, national brand foods (Pillsbury cake mix, Kraft macaroni & cheese, etc.), on the other hand, are analyzed once per year in a national collection. This is because these nationally available foods won’t likely show regional differences. In other words, Quaker oatmeal packets in Maryland probably look a lot like Quaker oatmeal packets in Nevada.

One way or another, these 280 foods eventually make their way to the laboratory. Once there, analysts prepare each food as it would be prepared in a typical household. For example, cantaloupe would be analyzed raw, while a boxed macaroni and cheese product would be cooked on the stovetop. Then each food is analyzed for many different compounds. Once we know the levels of different compounds in each individual food, we can estimate the exposure that someone would get from eating only one food or from eating all 280. FDA researchers monitor the data for trends and other interesting findings.

How many tests are there?

Analyses include pesticides, minerals, heavy metals, mycotoxins (toxins originating from mold), radionuclides (naturally occurring radioactive isotopes), and dioxin. It sounds scary, but rest assured that many of these compounds don’t generally occur at high levels in food. But the best way to keep the food supply safe it to monitor for them just in case. Each type of compound (pesticides, etc.) requires its own test. This means that there’s a whole lot of testing going on behind those laboratory walls. All of this testing, combined with a huge sample collection list, make the likelihood high that hazardous levels of any of these chemicals in the food supply would be noticed.

The bottom line

Everyone wants a safer food supply. The FDA aims to protect the food supply in a variety of ways, and the Total Diet Study is just one. The Total Diet Study provides not only a thorough picture of the levels of potentially hazardous compounds that might be present in a typical American diet; it also provides a safety net in the event that one of these chemicals enters the food supply at levels that are unsafe. That way we can take action if necessary. So you can sleep better at night knowing that someone is looking out for your carrots… and your chocolate cake.

Erica Bakota is a GovLoop Featured Contributor. After earning her PhD in chemistry at Rice University, she joined USDA as a research chemist, where she studied lipid oxidation and alternatives to partially hydrogenated oils. She then returned to Houston, Texas to join the Harris County Institute of Forensic Sciences, where she led method development and validation for the Forensic Toxicology Laboratory. In March 2018, she made a move back to the feds and is now with the FDA as a chemist at the Kansas City Laboratory. Her work at FDA focuses on active ingredients in dietary supplements and pesticide residues in foods. You can read her posts here.