Unexpected side effects of popular superfoods you didn't know about

Starting your day with a nutrient-rich meal can definitely boost your energy and digestion—but even the most celebrated superfoods can come with side effects.

From chia seeds and millets to cinnamon and cruciferous vegetables, these ingredients are packed with fiber, antioxidants, and essential nutrients.

But if you're not careful, they could lead to discomfort or even health issues, especially depending on your existing conditions or how they're consumed.

Chia seeds are often hailed as a superfood and praised by wellness influencers for their ability to curb cravings and aid in weight management. Once soaked in water, they take on a gel-like texture and are considered a natural alternative to Ozempic.

They're full of fiber, protein, healthy fats, and micronutrients, and can help manage cholesterol. However, too much fiber can trigger abdominal pain, constipation, diarrhea, bloating, and gas—particularly for people with inflammatory bowel diseases like Crohn’s or ulcerative colitis, where they can cause flare-ups. Eating them dry followed by water can also cause problems.

Millets like foxtail, barnyard, and black finger millet are nutrient-dense, gluten-free grains rich in protein, iron, magnesium, and vitamins such as thiamin, niacin, and folate. They're low in calories and known to suppress appetite, manage weight through tryptophan, and even reduce the risk of colon cancer. But too much millet can interfere with thyroid function because of goitrogens, which block iodine absorption and hormone production—potentially leading to goitre.

People with thyroid conditions should be cautious. Those with poor digestion may also experience bloating or indigestion. Millets also contain oxalates, which could contribute to kidney stone formation in susceptible individuals.

Cinnamon is a long-revered spice for both flavor and medicinal benefits. It’s anti-inflammatory, antioxidant-rich, and supports diabetes management. One review of 18 studies even found that it might help lower blood sugar. There are two types—cassia and ceylon—with ceylon offering more benefits. However, cassia cinnamon contains a compound called coumarin, and excessive intake could harm the liver.

“Research has found that eating too much coumarin may damage liver.” The safe intake limit is “0.1 milligrams (mg) per 1 kilogram (kg) or 2.2 pounds (lb) of body weight.” Overconsumption can also dangerously lower blood sugar. It may also interact with diabetes, liver, or heart medications.

Veggies like broccoli, cauliflower, cabbage, and Brussels sprouts are packed with fiber, vitamins C, E, K, and compounds that help reduce cancer risk and inflammation. They’re good for heart health, digestion, and blood sugar control. However, their fiber and sulfur content can cause gas and bloating.

They also contain goitrogens, which could interfere with thyroid function in people with iodine deficiency or thyroid issues, especially if eaten in excess. Cooking them thoroughly can help minimize those side effects.