The truth about harmful food combinations (and how to eat safely)

 Health warnings about certain food pairings, like grilled fish with pickled vegetables or tomatoes with cucumbers, often circulate online, sparking concerns about potential health risks. But how much of this is based on science, and how much is simply myth?

Nutrition experts emphasize that while some food combinations may have minor interactions, the human body is remarkably resilient. A balanced diet, proper cooking methods and mindful eating habits are far more important than avoiding specific pairings.

Grilled fish and pickled vegetables: A carcinogenic risk?

One common claim is that eating grilled fish with pickled vegetables can lead to the formation of nitrosamines, which are compounds linked to cancer. The theory suggests that amines in fish react with nitrates in pickled foods, potentially forming these harmful substances in the gut.

However, the process is far more complex than a simple food pairing. One's gut microbiome, overall diet and metabolism all play a role.

While nitrosamines can form under certain conditions, the risk is minimal when considering the bigger picture of a varied, antioxidant-rich diet. 

To reduce the potential risks of eating this food pairing:

• Increase your antioxidant intake - Foods high in vitamin C, like citrus fruits, bell peppers and leafy greens, can help block the conversion of nitrates into harmful compounds inside the body.
• Balance meals with fresh produce - Following a diet rich in whole foods supports gut health and reduces potential negative reactions.

Natto and raw eggs: A threat to biotin?

Another debated combination is natto (fermented soybeans) with raw eggs. Some claim that consuming raw egg whites with natto may lead to biotin deficiency, which can affect hair health. Raw egg whites contain avidin, a protein that binds to biotin, a B vitamin crucial for hair, skin and metabolism.

While occasional consumption is unlikely to cause harm, regularly eating large amounts of raw eggs, especially egg whites, may interfere with biotin absorption over time.

To reduce the potential risks of eating this food pairing:

• Cook eggs thoroughly - Heat deactivates avidin, eliminating the risk of biotin deficiency.
• Limit your raw egg intake - When consuming raw eggs, such as in smoothies or dressings, balance them with biotin-rich foods like nuts, seeds and whole grains.

Spinach and tofu: Do they cause kidney stones?

A long-standing myth suggests that eating spinach with tofu leads to kidney stones due to oxalates in spinach binding with calcium in tofu. However, the opposite may be true; calcium can actually help reduce oxalate absorption by binding to it in the digestive tract, preventing it from reaching the kidneys.

To reduce the potential risks of eating this food pairing:

• Choose calcium-rich tofu - Traditional tofu made with calcium coagulants is more effective at binding oxalates than silken tofu.
• Stay hydrated - Drinking plenty of water helps flush out excess oxalates.
• Avoid excessive vitamin C supplementation - High doses of vitamin C can increase oxalate production in the body.

Tomatoes and cucumbers: Do they cancel out vitamin C?

Some believe that cucumbers contain enzymes that destroy vitamin C in tomatoes. While cucumbers do have ascorbate oxidase, an enzyme that can break down vitamin C in lab settings, the human digestive system is far more complex.

Stomach acid neutralizes most enzymes before they can significantly affect nutrient absorption. Blending tomatoes and cucumbers into a juice may slightly reduce vitamin C levels, but eating them together in a salad poses no real risk.