What the texts say
The line comes from the Ashtanga Hridaya's passage on curd. It first names conditions where curd is used, coryza and painful urination, with the dry kind for grahani, and then turns to when not to eat it. The seasonal rule covers three seasons, not summer alone. The word used for summer is uṣṇa, "the hot season", and a variant reading of the same line, śarad-grīṣma-vasanteṣu, names summer (grīṣma) outright. The same line also says not to eat curd at night or hot.[1]
The modern view
The closest study we found is an adjacent one. It followed 78 healthy adults in rural India who ate differing amounts of fermented milk and soybean foods, and sampled their gut bacteria in summer, autumn and winter. Eating fermented foods was linked with shifts in gut bacteria across the seasons, and with lower diversity and bacterial load. This observational study looked at gut bacteria, not illness, so it cannot show that curd in summer does harm.[2]
From the classical texts
Questions people ask
Is curd good to eat in summer?
Not according to the Ashtanga Hridaya, which lists summer with spring and autumn as seasons for avoiding curd.[1]
Does the rule cover buttermilk or lassi?
This line is about curd (dadhi). Buttermilk and other curd drinks are not named in it.[1]
Related
Curd (dahi) at night
Charaka and the Ashtanga Hridaya both say not to eat curd at night. Charaka lists fever, skin disease and jaundice among the illnesses that follow.
FoodHeating curd (dahi garam karna)
Charaka says curd should not be eaten hot, and the Ashtanga Hridaya says the same in its passage on curd.
FoodHoney in hot weather (garmi mein shahad)
Charaka warns against honey for someone suffering from heat. Sushruta, as his commentator Dalhana reads him, extends it to summer and autumn.
FoodCurd and sugar (dahi-chini)
Charaka names sugar as one of the things curd should be eaten with. Dahi-chini is on his list of accompaniments, not his list of things to avoid.
Sources
- Ashtanga Hridaya, Sutra Sthana 5.31, GRETIL e-text.
- Jeyaram K, Lahti L, Tims S, Heilig HGHJ, van Gelder AH, de Vos WM, Smidt H, Zoetendal EG. Fermented foods affect the seasonal stability of gut bacteria in an Indian rural population. Nature Communications. 2025;16:771. PMID 39824829.
Updated 4 November 2026