Actually for food shots, the kit lenses are close enough.
You mean compared to the 14-42 (closest focus distance 0.25m) plastic mount kit lens? That is OK too.
The 12-50 has better spec and seems to be kit for higher end OMD. It has a metal mount and is weatherproofed. It has a so-called "macro" setting (focus range 0.2m to 0.5m) which is not a true macro but close enough for food shots.
Or else forget both and buy the Panasonic Lumix G VARIO 14-45 mm f/3.5-5.6 ASPH. M.O.I.S.lens. (closest focus distance 0.3m).
By the way, did you remember to set the E-P3 to IS mode 1 "on" when using the 17mm lens?
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But if you really want to buy a macro lens for micro 4/3, there are two excellent lenses.
• Panasonic Leica DG Macro-Elmarit 45mm F2.8 ASPH OIS
• Olympus M.ZUIKO DIGITAL 60mm f/2.8 ED Macro
Although both are excellent, the Panasonic Leica DG Macro-Elmarit 45mm F2.8 ASPH OIS may be easier to use. It has two focus range settings - Limit or Focus Full. There is an On/Off switch for the Mega OIS. This means you can leave it "On" to use the lens image stabilisation and turn off the E-P3 In-Body-IS when using this lens.
The Olympus M.ZUIKO DIGITAL 60mm f/2.8 ED Macro has 3 focus range settings, (this can be finicky) which some users find frustrating if they change subject quickly & forgot to set the correct range and spoil/miss the shot.