Mastu: Benefits, Evidence & Safety

TL;DR

Mastu is the thin whey-like liquid that separates from set curd in Ayurveda. Classical texts describe it as light, easy to digest, and useful for thirst, fatigue, and sluggish digestion: traditional claims, not clinical proof. No human trials of mastu itself exist; its modern study is limited to preparation and composition analysis. (52 words. Sources: Nathani et al., World J Pharm Res 2014; Kupati et al., Orient J Chem 2026.)

What it is

Mastu (also written dadhimastu) is the watery, whey-like liquid that collects over or separates from properly set curd (dadhi). It is distinct from whole curd: while curd itself is described in Ayurvedic texts as heavy and unctuous, mastu is the thin supernatant layer, classified as laghu (light) in nature (Nathani et al., World Journal of Pharmaceutical Research 2014; Kupati et al., Oriental Journal of Chemistry 2026). A 2026 pharmaceutics paper prepared dadhimastu by two methods and analyzed its organoleptic characters, pH, fat content, and inorganic elements, finding that four-layer cloth filtration reduced fat content with only minimal change to pH, which the authors linked to better digestibility and acceptability for people whose agni (digestive fire) is impaired (Kupati et al., 2026).

Traditional use

Classical Ayurvedic sources describe mastu as light (laghu), strength-promoting (balya), and appetite-kindling: it is said to create desire for food, be relishing, alleviate fatigue (klama) and thirst (trishna), pacify kapha and vata, cleanse the microchannels (srotovishodhana), and help remove accumulated feces (Nathani et al., 2014). Sushruta and Bhavamishra are cited for similar properties, laghu, vata-pacifying (vatashamaka), relieving exhaustion (glani), kindling agni, and loosening the bowels, with the Raj Nighantu noting its use for morbid thirst, gulma (phantom tumor), pliha (splenomegaly), and arsharoga (hemorrhoids) (Kupati et al., 2026). Mastu is also used beyond diet: in panchakarma therapies and in rasaushadhi pharmacy, for example in the preparation (marana) of Tuttha bhasma (calcined copper sulfate) (Kupati et al., 2026). These are records of traditional practice, not clinical proof.

What modern research says

Preparation and composition (laboratory study). Kupati et al. (2026) prepared dadhimastu by two methods and measured organoleptic characters, pH, fat content, and inorganic elements, reporting that cloth filtration lowered fat content and marginally shifted acidity while minimally changing pH: a change the authors associated with improved digestibility and acceptability for people with impaired digestive fire (Kupati et al., 2026).

Clinical evidence for health benefits: essentially absent. The same 2026 paper explicitly notes that "research studies specifically focusing on Dadhimastu in Ayurveda has been limited," even though much has been published on curd (dadhi) itself (Kupati et al., 2026). We found no published human clinical trial testing mastu for thirst, fatigue, digestion, or any other outcome. Broader reviews of curd note modern nutrition's interest in its probiotics, calcium, protein, and B vitamins: but those findings concern curd as a whole, not the separated whey liquid (IJRAR review of Dadhi). Traditional claims for mastu should therefore be read as traditional, not as established effects.

Safety & contraindications

No pharmacopoeial safety monograph or dedicated safety study of mastu was found (Kupati et al., 2026). As a traditional dairy food, the whey-like liquid of set curd, it has a long history of dietary use, but that history is not a safety trial. Because it derives from curd (Nathani et al., 2014), people with cow's-milk allergy or significant lactose sensitivity should be cautious. In the absence of safety data, anyone using mastu in medicinal quantities, rather than as an occasional food, should talk to a qualified clinician first.

FAQs

What exactly is mastu?

Mastu (dadhimastu) is the thin, watery liquid that separates from and sits over properly set curd (dadhi): the Ayurvedic equivalent of curd whey. Classical texts distinguish it from whole curd, describing it as light (laghu) rather than heavy, and it has both dietary and pharmaceutical uses in Ayurveda (Nathani et al., 2014; Kupati et al., 2026).

How is mastu different from takra (buttermilk)?

Takra is buttermilk, the liquid left after churning curd to extract butter, while mastu is the whey-like supernatant that separates from undisturbed set curd. Both are lighter than whole curd and both are used in Ayurvedic dietetics and pharmacy, but they are prepared differently and described separately in the classical literature (Kupati et al., 2026).

Is there any clinical evidence that mastu helps digestion or fatigue?

No. We found no published human clinical trial of mastu for any health outcome. Its traditional reputation for easing thirst, fatigue, and sluggish digestion comes from classical Ayurvedic texts, and modern published work is limited to how it is prepared and its basic composition (Kupati et al., 2026). Treat benefit claims as traditional, not proven.

Is mastu the same as the whey in whey-protein supplements?

Not exactly. Both are the watery fraction of dairy, but commercial whey protein is a concentrated, processed product of cheese-making, whereas mastu is the simple supernatant of set curd in a traditional kitchen or pharmacy preparation. Nutritional equivalence between the two has not been studied (Kupati et al., 2026).

Who should avoid mastu?

People with cow's-milk allergy or significant lactose intolerance should be cautious, since mastu is the whey-like liquid of set curd: a dairy derivative (Nathani et al., 2014). No dedicated safety studies exist, so medicinal-quantity use should be discussed with a qualified practitioner. As an occasional traditional food, it has a long history of dietary use: but history is not the same as safety data (Kupati et al., 2026).

Sources

This article is for educational purposes only and is not medical advice. Consult a qualified practitioner before using any Ayurvedic preparation for a health condition.