Eating is something all humans must do to survive, but, for many people, eating good food is the spice of life. In this modern, globalized world, people have access to more varieties of food than ever before. Although we might know the ingredients that go into a dish, there are a few surprising substances found in very common foods. Do you really know what you’re eating? Maybe not.

Call it heavy metal

People old enough to remember thermometers that weren’t digital are familiar with mercury. It is the liquid that rose and fell with the temperature and the reason adults never wanted children to touch thermometers. Mercury is a natural metal found environmentally, but it is the last thing anyone would expect to end up on a dinner plate. Tuna, swordfish, king mackerel, shark, tilefish, and orange roughy have the highest levels of mercury in fish. Although some of those fish are specialty items that a person wouldn’t necessarily eat on a regular basis, tuna, specifically the big eye and ahi varieties, has the potential to be hazardous.

Although there are some natural forms of mercury, mercury from pollution causes the most contamination of food. Unfortunately, the ocean is being used as a dumping ground for garbage and industrial waste. Various forms of mercury are either dumped into the ocean or eventually settle there as a byproduct of many major industries. When a body of water is contaminated by mercury, eating any fish from that water will expose a human to a certain level of mercury, but levels are especially high in bigger carnivorous fish like tuna and shark. Since these fish eat smaller fishes, their bodies become contaminated with the mercury they are already exposed to as well as the mercury its prey has been exposed to.

Experts suggest that pregnant women and women trying to become pregnant avoid eating any of the aforementioned fish varieties because exposure to mercury can permanently stunt a baby’s brain development. Studies have shown that children whose mothers eat lots of fish during pregnancy are more likely to have learning disabilities later in life. Due to these risks, it is also recommended that children who are younger than seven years old avoid eating these types of fish.

The sour side of honey

Honey is a natural food, and many professionals agree that, in moderation, it can be good for humans. Some doctors even tell patients to eat a spoonful of local honey each day to reduce the impact of seasonal allergies. As beneficial as honey may be, honey can have a hidden toxin. Honey is made by bees, so pollen and other debris from the plants they pollinate inevitably get into the sweet substance.

A naturally occurring poisonous substance called grayanotoxin is in the nectar of all flowers in the rhododendron family. When a bee gets nectar from this plant and then makes honey, people who eat the honey can suffer from a group of symptoms known as mad honey disease. This substance stops the brain’s ability to process sodium correctly. It also causes the vagus nerve, a part of the brain that controls important bodily functions like the heartbeat, to react in a manner very similar to when the body is under anesthesia.

A person suffering from this disease usually starts to feel symptoms within two hours of eating contaminated honey. The toxins cause the blood pressure to drop and the heart rate to increase, which is a dangerous combination. Especially if a person already has a weak heart, this chain of events can lead to a heart attack or even death. Mad honey disease often causes dizziness, vomiting, and nausea. Sweating is also common, and some people fall into a half-conscious stupor. In very serious cases, a person may pass out, experience blurred vision or double vision, or even go into convulsions.

There’s a beetle on your plate

Some of the most brilliant, vibrant hues of red can be found in nature, so it only makes sense that food companies would want to use a natural substance to die foods red. Strangely enough, crushed cochineal beetles are used to make foods red. The female beetles have more pigment, so they are used exclusively for cochineal extract. As disgusting and inhumane as the process of crushing bugs to make dye may sound, cochineal extract is one of the healthiest red pigments to digest. The beetles are completely benign to humans, and foodies can avoid all of the side effects and allergies that come along with unnatural red dyes.

The new trans fat

Just as soon as the public discovered the dangers of trans fats, the mad scientists who work for major food corporations came up with another Frankenstein of fats. Interesterified fats are oils that have been modified at the molecular level so that it tastes the same but spoils slower and melts at lower temperatures. These types of fats are added to many of the same processed foods that made big announcements about removing trans fats.

Food manufacturers are not required to list the amount of interesterified fats separately on nutrition labels, so a person must carefully read the ingredients to determine if this fat is in their food. So far, research has not proven that this fat has any strange side effects or causes cancers. The biggest danger of this newer type of fat is that many people think they are making a healthy decision by avoiding trans fats, but they are actually consuming a substance that is just as unhealthy.