Can Onions Improve Insulin Resistance? A Human Trial Offers Clues

By Tahani Elghazaly
Published October 13, 2026

Latest news on WhatsApp أجدد الأخبار على واتساب

A randomized clinical trial testing fresh yellow onion consumption produced an intriguing result: women receiving chemotherapy for breast cancer showed improvements in fasting glucose, insulin and several markers related to insulin resistance after eight weeks of higher onion intake.

The study enrolled 56 women aged 30 to 63 with invasive ductal breast cancer who were receiving doxorubicin-based chemotherapy. After their second chemotherapy cycle, participants were randomly assigned to one of two dietary groups.

Women in the higher-intake group consumed between 100 and 160 grams of fresh yellow onion each day, adjusted according to body mass index. The comparison group consumed 30 to 40 grams daily. The intervention continued for eight weeks, and 23 participants in each group were included in the final analysis.

By the end of the trial, the higher-onion group showed reductions in fasting blood glucose and insulin. Researchers also reported improvement in HOMA-IR, a research measure used to estimate insulin resistance, along with changes in QUICKI, an index of insulin sensitivity.

The contrast between the two groups was particularly notable. HOMA-IR declined within the higher-onion group while increasing in the lower-intake group during the study period, and relative changes in fasting glucose and insulin-resistance measures favoured the higher-intake group.

The researchers concluded that higher fresh-yellow-onion consumption was associated with improved hyperglycemia and insulin resistance in this specific group of women undergoing chemotherapy.

That distinction is crucial. The trial was small and involved a highly specific patient population. It did not establish onions as a treatment for insulin resistance in the general population, nor did it test people with ordinary prediabetes or type 2 diabetes outside the chemotherapy setting.

The finding is therefore best understood for what it is: a controlled human experiment that produced a measurable metabolic effect and a reason for larger trials—not a prescription.