Verse 5.2.1

स होवाच किं मेऽन्नं भविष्यतीति यत्किंचिदिदमा श्वभ्य आ शकुनिभ्य इति होचुस्तद्वा एतदनस्यान्नमनो ह वै नाम प्रत्यक्षं न ह वा एवंविदि किंचनानन्नं भवतीति ॥ ५.२.१ ॥

sa hovāca kiṃ me'nnaṃ bhaviṣyatīti yatkiṃcididamā śvabhya ā śakunibhya iti hocustadvā etadanasyānnamano ha vai nāma pratyakṣaṃ na ha vā evaṃvidi kiṃcanānannaṃ bhavatīti || 5.2.1 ||

1. Prāṇa then asked, ‘What will be my food?’ The other organs said: ‘Anything that even dogs, birds, and other animals can eat in this world is your food.’ All that is food for ana. Ana is a name of prāṇa. For one who knows this nothing is uneatable. [That is, he can eat any food that an animal can eat.]

Word-for-word explanation:

Saḥ ha uvāca, he [prāṇa] asked; kim me annam bhaviṣyati iti, what will be my food; iti ucuḥ ha, [the other organs] replied; ā-śvabhyaḥ ā-śakunibhyaḥ, for dogs as well as birds; yat idam kiñcit, whatever there is; tat vai, all that; etat anasya annam, is this food for prāṇa; anaḥ ha vai nāma pratyakṣam, ‘ana’ is the name of prāṇa itself; ha vai evam vidi, for one who knows thus; kiñcana na anannam bhavati iti, nothing becomes uneatable [i.e., anything an animal can eat is food for him].

Commentary:

There is some difference between the words prāṇa and ana. Prāṇa has a limited meaning. It refers to something characterized by breathing. It breathes, and in order to keep breathing it needs food. It may be a specific kind of food. It may not eat every kind of food. Ana, however, is that which can eat any kind of food.

The Bṛhadāraṇyaka Upaniṣad (1.5.23) says, ‘The sun rises and sets in prāṇa.’ It also says that the person who knows the true nature of prāṇa is one from whom the sun rises and into whom it sets.