What do Buddhists do to prevent sexual desires? Does Buddhism do anything to prevent sexual desires?

Do they do anything to lower sexual desires? 

Prevent eating certain foods or something similar?
Yes, they do something to lower sexual desire. Sexual desire is a form of sensual desire which is the first of the 5 Hindrances to meditation practice. The commentaries to the Satipatthana Sutta list 6 antidotes for sensual desire:

Learning how to meditate on impure objects
Devoting oneself to the meditation on the impure
Guarding the sense doors
Moderation in eating
Noble friendship
Suitable conversation

The first two methods refer to the practice of Asubha Bhavana (the meditation on the foulness and impurity of the body), which explicitly counteracts sexual lust and is one of the Four Protective Meditations. In this technique you examine your own body by looking at  each of the 32 body parts individually. The purpose is to see the sign of the unattractive nature of the human body.

&quot;And further, O bhikkhus, a bhikkhu reflects on just this body hemmed by the skin and full of manifold impurity from the soles up, and from the top of the hair down, thinking thus: 'There are in this body hair of the head, hair of the body, nails, teeth, skin, flesh, fibrous threads (veins, nerves, sinews, tendons), bones, marrow, kidneys, heart, liver, pleura, spleen, lungs, contents of stomach, intestines, mesentery, feces, bile, phlegm, pus, blood, sweat, solid fat, tars, fat dissolved, saliva, mucus, synovic fluid, urine.'
&quot;Just as if, O bhikkhus, there were a bag having two openings, full of grain differing in kind, namely, hill-paddy, paddy, ...; and a man with seeing eyes, having loosened it, should reflect thinking thus: 'This is hill paddy; this is paddy, ...' In the same way, O bhikkhus, a bhikkhu reflects on just this body hemmed in by the skin and full of manifold impurity from the soles up, and from the top of the hair down, thinking thus: 'There are in this body: hair of the head, hair of the body, nails, ...' - MN 10

A very good practical guide is in the video series of Bhikkhu Bodhi's course of the 4 protective meditations