15 healthy foods that are harmful to overeat

First off, it’s worth highlighting that most people don’t even come close to getting as many vegetables as they should in their daily diet, so don’t use this as an excuse to avoid the greens you need. Think of this warning as inspiration to eat the full rainbow when it comes to your vegetables. “Broccoli is a superfood that is packed with potent antioxidants known to reduce the risk of cancer and heart disease, but when eaten in very large amounts, broccoli may lead to hypothyroidism (low thyroid),” say the Nutrition Twins, Lyssie and Tammy Lakatos Shames, authors of The Nutrition Twins’ Veggie Cure. “This is because they contain thiocyanates, which can make it difficult for your body to absorb iodine. If you’re someone who has dealt with thyroid issues in the past, be sure not to consume very large amounts of broccoli.”

The list of health experts and fitness influencers who swear by their morning lemon water is seemingly infinite. “It’s a very low-calorie, low-sugar beverage that encourages drinking,” explain The Nutrition Twins. “It helps you stay hydrated with its fresh flavour while also providing some immune-boosting vitamin C and antioxidants that may help to protect your cells from damage. However, if you drink a lot of lemon water, the acid from the lemon stays on your teeth and can damage your tooth enamel, which makes your teeth prone to cavities.” If you do drink a lot of lemon water, the twins recommend rinsing your mouth afterwards and drinking with a straw to minimise contact with your teeth.

The problem with cow-milk alternatives, such as almond, oat, hemp, soy, coconut and rice milks, is that they’re often very processed and have lots of added sugars. In fact, these plant-based milks usually have little of the actual plant, says Keith-Thomas Ayoob, associate clinical professor at Albert Einstein College of Medicine. “A glass of the average almond milk, for example, only has about four almonds,” he says.

“More accurately, coconut fat at room temperature is solid owing to its near-total saturated fat content,” says Ayoob. Contrary to coconut oil’s popularity among the foodie glitterati, there’s no actual science to suggest coconut oil is healthy, he says. “Go for extra-virgin olive oil, canola, grape-seed or other unsaturated oils as a healthier alternative. And watch out for portion size: no matter the type of oil you’re using, they all have lots of calories, so use them sparingly,” Ayoob warns.

Confused about what oil to use? When it comes to cooking oils, there are three things to consider.

Tuna is a versatile and inexpensive source of protein, magnesium, zinc, iron and omega-3 fatty acids. “If, however, you’re choosing solid albacore or tuna steaks several times a week, you’re likely getting too much mercury, which is a neurotoxin,” say the Nutrition Twins. “Mercury poisoning can lead to muscle weakness and vision changes.” To avoid any danger, they recommend for the light tuna instead of albacore if you eat tuna regularly. “Pregnant women and children are advised to choose the lowest mercury-containing fish and limit their intake to no more than two times per week.”

Although it makes the list of 15 foods nutritionists try to eat every day, Kimchi should be eaten in moderation. Kimchi is pickled cabbage and a good source of vitamin A, vitamin C and gut-healthy prebiotic fibre, say the Nutrition Twins. Plus, the kick of flavour is a tasty way to eat your veggies. But it also happens to be high in sodium – the 670-plus milligrams per 100 grams which translates to about a third of your recommended maximum sodium intake, they warn. “Combining a few servings of kimchi with the food you eat in your day and you’ll go well beyond the sodium limit, increasing your risk of developing high blood pressure and congestive heart failure,” the twins say.

Most people can drink green tea with no worries: “It’s packed with catechins, powerful antioxidants that help fend off cancer, inflammation and heart disease,” say the Nutrition Twins. “However, the tannins found in green tea can also interfere with the absorption of non-heme iron (iron from plant-based sources), so if you have low iron levels or are at risk of iron deficiency (some athletes, elderly, pregnant women, and vegetarians who don’t consume enough iron) avoid drinking green tea with meals and just drink it between them.”

While citrus fruit is healthy for most people, Ayoob points out that grapefruit, tangelos, minneolas, pummelos and more can interfere with a long list of medications, including some statins and antihistamines. “Interaction varies with the medication, but can result in very high blood levels of the drug, or sometimes decreased absorption of the drug, when taken within 72 hours of consuming these citrus fruit.” If you’re taking medication, always check with your doctor or pharmacist to make sure you can safely consume citrus fruit.

When it comes to weight loss, fibre – the part of a carbohydrate your body can’t digest – is incredibly important. It swells in the stomach to make you feel fuller longer, meaning you can lose weight without hunger. However, if you’re not used to plenty of fibre in your diet, eating too much at once can cause gas and bloating. “This is typical but annoying and can be socially awkward,” says Ayoob. “You really need to introduce fibre gradually and consistently if you’re used to a low-fibre diet.”

How do you know if you are not getting enough fibre in your diet? Your bowel movements!

“These are great foods with tons of antioxidants, minerals and vitamins,” says Ayoob. “The problem for people on blood-thinning medications, like warfarin, is that they’re high in vitamin K, a nutrient that helps blood to clot.”