Can Consuming Certain Carbs Increase Lung Cancer Risk?

Lung cancer has long been linked with smoking and air pollution. But in 2025, researchers are increasingly turning attention to diet as a potential contributing factor. A recently highlighted study, widely discussed this week, reported a worrying association between high-glycaemic index (GI) carbohydrate diets and elevated lung cancer risk. In other words, the type of carbs you consume may matter, not just the fact that you eat them. This finding is especially relevant for countries like India, where refined grains, white rice, sugary snacks, and processed carbohydrates make up a substantial part of daily meals. While smoking and pollution still remain the primary drivers of lung cancer, the new evidence adds dietary habits to the list of modifiable risk factors.

The study's conclusions are prompting nutritionists and public-health experts to urge caution, and to reconsider the widespread assumption that all carbohydrates are equal.

What The Study Found: High-GI Carbs Linked To Higher Lung Cancer Risk

The new research compared how different carbohydrate diets influence lung cancer risk. Specifically, individuals consuming diets high in glycaemic index (GI), meaning foods that rapidly raise blood sugar (like white bread, refined grains, sugary drinks), had about a 13% higher risk of developing lung cancer compared with those eating lower-GI carbs. The increased risk applied to both non-small cell lung cancer (NSCLC) and small-cell lung cancer (SCLC).

Interestingly, the same study found that a higher glycaemic load (GL), a measure of total carbohydrate intake adjusted for quantity and quality, was associated with up to a 28% lower lung cancer risk, especially for NSCLC.

What does this paradox mean? Not all carbs are equal. Frequent consumption of high-GI, refined carbohydrates appears linked to elevated risk, while whole-grain carbs, fibre-rich foods, fruits, vegetables and plant-based carbs seem protective.

Why High-GI Foods Might Raise Cancer Risk

Researchers suggest mechanisms that could explain these findings. High-GI foods trigger rapid spikes in blood sugar and insulin, which over time may lead to chronic metabolic stress, inflammation, and elevated levels of growth factors (like insulin-like growth factor-1, IGF-1). These changes can potentially promote abnormal cell growth, a hallmark of cancer development.

In contrast, diets rich in whole grains, fibre and plant-based carbohydrates help stabilise blood sugar, reduce insulin spikes, and lower inflammation, possibly helping keep lung tissue healthier over the long run.

What This Means For Your Diet

• Avoid frequent high-GI foods such as white bread, white rice, refined flours, sugary snacks, soft drinks and processed grains.
• Choose whole grains and fibre-rich foods: whole wheat, brown rice, rolled oats, millets, legumes, pulses, vegetables, fruits.
• Balance total carb intake with moderate quantity, quality over quantity, avoid processed ultra-refined carbohydrates.
• Adopt a plant-based dietary pattern when possible, emphasising natural foods over processed items.
• Experts say that while smoking cessation and reducing pollution remain the most important steps to prevent lung cancer, dietary improvements can be a complementary tool, especially for non-smokers or those with minimal pollution exposure.

What The Study Doesn't Prove: Important Limitations

• The association between high-GI diets and lung cancer is moderate (around 13% increase), far smaller than the risk linked to smoking or air pollution.
• Most studies are observational and cannot prove that high-GI carbs cause lung cancer, only that they are associated.
• Diet, lifestyle, genetics and environmental factors together influence cancer risk. Carbs are only one piece of the puzzle.
• Researchers emphasise the need for more studies, especially in diverse populations (including Indian diets) before drawing firm conclusions.

The newly highlighted study linking high-GI carbohydrate diets with a small but measurable rise in lung cancer risk highlights an important, and previously underappreciated, dimension of lung health: What you eat. This doesn't mean you must completely avoid carbs or panic, but it does call for a smarter, more conscious approach to choosing the kinds of carbohydrates on your plate.

Switching to whole grains, fibre-rich foods, and plant-based carbs, while reducing refined and processed carbohydrates, may help cut the risk. Combined with avoiding smoking, reducing pollution exposure, and maintaining overall healthy habits, diet becomes another tool in the fight against lung cancer. In short, carbs are not "bad", but quality matters more than quantity.

Disclaimer: This content including advice provides generic information only. It is in no way a substitute for a qualified medical opinion. Always consult a specialist or your own doctor for more information. NDTV does not claim responsibility for this information.