- Nutritionists generally advise avoiding sugary, processed items in favour of whole foods like fruits, nuts, and whole grains.
- But even a few foods and drinks considered healthy can have negative side effects when consumed in excess.
- We rounded up a few nutritious items that have been found to contain certain toxins or cancer-causing properties.
- Visit BusinessInsider.com for more stories.
Many of us have been told that swapping starchy potatoes for a plate of green beans is good for our bodies. But not all nutritionist-recommended foods and drinks are unequivocally healthy.
A few of the foods considered healthy that you’ve been told to eat, including spices, nuts, fruits and veggies, and even nutritional supplements, could have negative side effects when consumed in excess. But that doesn’t mean you should stop eating them.
One of the general principles of toxicology is that the dose makes the poison. We can get sick when we’re exposed to chemicals in extremely high amounts, but it’s usually difficult to eat so many servings of a single food that we see negative health effects.
That said, scientists are constantly learning more about the relationship between food and our bodies. Here are a few foods and drinks that have been found to contain certain toxins or cancer-causing properties, as well as a few that may lead to higher health risks.
Red wine has an ingredient that could help your heart, but drinking too much of it could increase your risk of cancer or a stroke.
There’s an ongoing debate about whether red wine’s salutary properties make up for the fact that it’s, well, alcohol.
Studies have found that antioxidants in red wine could help ward off heart attacks by reducing the risk of blood clots, inflammation, and high cholesterol.
But drinking alcohol in excess isn’t recommended for your health.Too much alcohol (more than one drink a day for women or more than two drinks a day for men under 65) could increase your risk of high blood pressure, stroke, or certain types of cancer.
Fish-oil supplements contain essential omega-3s, but they might also increase your risk of bleeding.
Americans spend more than $US1 billion a year on fish- and animal-derived supplements, with many under the impression that these nutrients can reduce inflammation or cardiovascular risk. This seems to be the case only for people who don’t eat any fish or have elevated triglyceride levels.
The Mayo Clinic even suggests that high doses of fish-oil supplements could increase your risk of bleeding or a stroke, or hinder your immune response. Though the clinic says the supplements are “generally safe,” doctors tend to advise people to get their omega-3 fatty acids from whole foods if possible.
Store-bought cinnamon is generally considered a healthy treat, but it could be toxic for your liver.
Cinnamon is often touted as a yummy way to consume antioxidants that reduce inflammation and blood-sugar levels, which can in turn lower your risk of heart disease or Type 2 diabetes. But not all cinnamon is created equal.
The spice comes in two main forms: the kind we see most often in stores, known as cassia, and the rarer, more expensive version, known as Ceylon.
Store-bought cinnamon has a much higher percentage of coumarin, an organic compound that could damage liver cells and lead to cancer. Because of this, the average person is generally advised not to consume more than 1 to 1 1/2 teaspoons of cassia cinnamon each day.
Nutmeg might also be a cause for concern because of its hallucinogenic properties.
Nutmeg is an ancient remedy for pain and digestive issues, but it’s potentially toxic in large doses. The spice contains a substance called myristicin, which has been known to have hallucinogenic properties.
A 2015 study found that just 5 grams of ground nutmeg, or about 2 teaspoons, could be considered a “toxic dose” because of its hallucinogenic effects – but humans would likely need to consume much more for it to become an actual health risk.
Coffee contains acrylamide, a chemical that’s been linked to cancer.
Many scientific studies have found associations between drinking coffee and several health benefits, including longer life spans and reduced risk of a heart attack. But some researchers think it could be linked to cancer, since a potentially carcinogenic chemical called acrylamide forms when coffee beans are roasted.
Last spring, a California judge ruled that coffee companies must post warnings about acrylamide in accordance with Proposition 65, a state law that requires businesses to alert residents about significant exposures to toxic chemicals.
Thus far, studies have found that acrylamide can lead to cancer in rats and mice that get exposed to the chemical at much higher doses than what humans would encounter.
Though a single cup of coffee doesn’t contain enough acrylamide to endanger human health, the average American drinks almost two cups a day, which could increase their exposure with time.
Green tea might be one of the best drinks for your health, but too-hot green tea could be linked to cancer.
There’s promising scientific evidence that green tea can lower cholesterol and interfere with the replication of cancer cells. But drinking anything that’s too hot could have a negative effect on your esophageal health.
The International Journal of Cancer recently published a study that said that frequently drinking very hot tea could increase the risk of esophageal cancer. The researchers found that drinking three cups of tea at more than 140 degrees Fahrenheit a day increased the risk of esophageal cancer by about 90% among 50,000 people aged 40 to 75 compared with drinking three cooler cups daily.
Preliminary studies have also found that green-tea extract may be damaging to your liver, but more research is needed to determine the risk.
Tuna is a lean protein, but it’s also high in methylmercury, an environmental toxin that can cause developmental issues in children.
Studies have found that even low-level exposure to methylmercury can impair memory and fine motor function in adults. It can also cause developmental issues in children, which is why pregnant people are generally advised to reduce their consumption of canned tuna.
But pregnant people aren’t the only group that should be concerned. A 2018 Harvard study found that tuna accounted for 37% of the US’s intake of methylmercury through fish.
Even a handful of Brazil nuts could contain too much selenium.
Brazil nuts contain more than 770% of the daily recommended value of selenium, an essential mineral that can help with fertility and brain function. Too much selenium can cause nausea, fatigue, or, in extreme cases, kidney and heart failure.
Adults are advised not to consume more than 400 micrograms of selenium per day, but about six to eight Brazil nuts would put you over that limit.
Rhubarb is fine to eat — just not the leaves. They contain high amounts of oxalic acid, which is poisonous to humans.
Rhubarb is chock-full of essential nutrients like manganese and vitamin K, but its leaves are poisonous to humans. That’s because they’re high in oxalic acid, which can cause severe burning, vomiting, kidney failure, and in some cases death.
While a person would have to eat about 10 pounds of rhubarb leaves for the food to be lethal, we shouldn’t consider it edible. The British government learned this in World War I, when it recommended eating rhubarb leaves as a way to address the food shortage. It resulted in multiple sicknesses and at least one death.
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