Daily nutrition consisted of a sort of bread called biscuit or tack, that was cooked twice. To prepare the biscuit stews, which were the basic daily food, they added salted bacon, meat and cod, or dehydrated vegetables such as onion and garlic. Additionally, they tended to have legumes and dry grains: small beans, peas, rice, etc. When inclement weather prevented them from lighting a fire on board, they made their meals with cheese and biscuit. Fresh food did not last long without spoiling, so it had to be consumed immediately. The most typical drinks were wine and water.

During the first expedition to the Mollucas under Magellan's command, the sailors suffered great hunger and thirst while crossing the Pacific. As Pigafetta recorded in his journal:

“... The biscuit we were eating had ceased to be bread; rather, it was dust mixed with worms that had devoured its entire substance. Furthermore, it bore an unsupportable stench, impregnated with rat urine. The water we were forced to drink was also spoilt and reeked. To stave off death from hunger, we were forced to eat pieces of cowhide that had been used to line the yardarm to prevent the wood from destroying the ropes. So tough was this leather, ever exposed to water, sun and wind, that it had to be immersed for four to five days in the sea so as to soften it a bit; to eat it, we then forthwith placed it on the coals. We were often reduced to eating sawdust, and even the rats, so repugnant to men, had become such a delicacy that one paid half a ducat for each."

The lack of fresh food led to serious illness, especially the dreaded scurvy. Urdaneta himself wrote in his log:

“...All these men perished of gums so swollen that no food could pass, together with a pain in the breast; I witnessed them remove flesh as thick as a finger from a man's gums, only for the gum to burgeon once more the following day as if nothing had been removed...”.