In plain words
Becoming the digestive fire within the bodies of living beings, joined with prāṇa and apāna, I digest the four kinds of food.
Word for word
I, having become Vaiśvānara, dwelling in the body of living beings, joined with prāṇa [and] apāna, digest the fourfold food.
अहं वैश्वानरो भूत्वा प्राणिनां देहमाश्रितःप्राणापानसमायुक्तः पचाम्यन्नं चतुर्विधम्
Other commentaries
The commentators
▸Bhagavadgītābhāṣyam
किञ्च —
अहमेव वैश्वानरः उदरस्थः अग्निः भूत्वा — ‘अयमग्निर्वैश्वानरो योऽयमन्तः पुरुषे येनेदमन्नं पच्यते’(बृ. उ. ५ । ९ । १) इत्यादिश्रुतेः ; वैश्वानरः सन् प्राणिनां प्राणवतां देहम् आश्रितः प्रविष्टः प्राणापानसमायुक्तः प्राणापानाभ्यां समायुक्तः संयुक्तः पचामि पक्तिं करोमि अन्नम् अशनं चतुर्विधं चतुष्प्रकारं भोज्यं भक्ष्यं चोष्यं लेह्यं च । ‘भोक्ता वैश्वानरः अग्निः, अग्नेः भोज्यम् अन्नं सोमः, तदेतत् उभयम् अग्नीषोमौ सर्वम्’ इति पश्यतः अन्नदोषलेपः न भवति ॥ १४ ॥
In plain words
And there's more —
It is I alone who become Vaiśvānara, the fire that lives in the belly, just as scripture says: 'this fire, Vaiśvānara, dwelling within the person, is the very fire by which food is digested' (Bṛhadāraṇyaka Upaniṣad 5.9.1). As Vaiśvānara, I take up residence in the body of every breathing creature, joined with the in-breath and the out-breath, united with them, and I digest food of all four kinds: what is chewed, what is bitten, what is sucked, and what is licked. And for anyone who sees it this way, 'the one who enjoys is Vaiśvānara, the fire itself; what is enjoyed, the food, is Soma; and this whole pair together, fire and Soma, is everything there is,' no stain from eating ever touches them.
Close to the Sanskrit
Moreover —
I alone, becoming Vaiśvānara, the fire situated in the belly — as the Śruti says, 'this fire, Vaiśvānara, which is within the person, by which this food is digested' (Bṛhadāraṇyaka Upaniṣad 5.9.1), etc.; being Vaiśvānara, having taken refuge in, entered, the body of living, breathing creatures, joined with prāṇa and apāna, united with the in-breath and out-breath, conjoined, I cook, I perform the digesting, of food, of nourishment, of four kinds, four sorts: to be chewed, to be bitten, to be sucked, and to be licked. For one who sees, 'the enjoyer is Vaiśvānara, the fire; the enjoyed, the food, is Soma; this pair together is Agni and Soma, everything' — for such a person, no taint of the fault of food arises. || 14 ||