Traumatic experiences from disasters have enduring effects on health, both directly and indirectly by influencing health behaviours. Among potential pathways, the impact of disaster-related trauma on dietary patterns has been understudied. This study investigated the relationship between disaster-related trauma and dietary inflammatory index (DII®), and how these relationships differed by gender and whether they prepare meal by themselves or not among older survivors of the 2011 Great East Japan Earthquake and Tsunami (n 1375). Dietary data were collected in 2020 using a brief-type self-administered diet history questionnaire, from which we derived a dietary inflammatory index (DII®) based on twenty-six food/nutrient items, where higher scores indicate pro-inflammatory (i.e. unhealthy) diet. We found that the experience of housing damage due to the earthquake and tsunami was associated with slightly higher DII scores (coef. = 0·38, 95 % CI −0·05, 0·81). Specifically, women who cooked by themselves tended to have higher DII when they experienced housing damage (coef. = 1·33, 95 %CI −0·63, 3·28). On the other hand, loss of friends was associated with a lower DII score (coef. = −0·28, 95 % CI −0·54, −0·01). These findings highlight the importance of providing support to groups who are at increased risk of deterioration in dietary quality in the aftermath of disasters.