Ova non grata is over. At least for some egg fans. After being bad- mouthed for years by well-meaning cholesterol bores and, more recently, held up as a major salmonella hideout, eggs have found a cheerful, energetic champion in author and syndicated columnist Marie Simmons.

Her latest book, The Good Egg (Houghton Mifflin, $27), offers 200 recipes that use eggs in all kinds of delicious dishes. Along the way, she deals calmly with the negatives we've all heard and accentuates the positives.

4``Moderation is the key,'' Simmons said during a recent swing through Chicago on a tour promoting the book. It was 9 a.m.; she had risen at 4 to do an egg demo for a TV show; at least one more demo was scheduled for the afternoon.

Book tours are not about moderation, but Simmons was coping. She seems to concentrate on balance: not too much of any one thing, and remember to stir.

4``I never felt eggs were bad,'' she went on. Maybe people ate too many, but too much of any food puts a diet off-balance. ``You don't need four eggs and eight slices of bacon.''

That breakfast must be the ``heart attack on a plate'' we've been warned about for years. Except that now, word is trickling in that eggs might not be the bad guys.

``The new research is showing that (the problem) might have been that bacon,'' Simmons said, ``because it's the saturated fat that the research is indicating may be more serious in terms of building serum cholesterol, as opposed to it coming from dietary cholesterol.''

Just before this three-year egg project started, Simmons' usually low cholesterol level was found to be inching into the 190s. How would 18 months of intensive recipe-testing affect her?

To counter the daily tastings of eggs and rich dairy products, Simmons increased her exercise to five days a week at the gym: aerobics, weights, exercise machines. On non-gym days, she practiced yoga.

She didn't lose any weight, she said. But the doctor who'd noted her stealthily rising cholesterol checked it again after the egg/- exercise binge. At our interview, Simmons still was pumped about what the doctor found: ``My cholesterol went down more than 20 points.''

One egg fear sent packing.

OK, what about salmonella? Ways to prevent or minimize it are offered throughout the book, but this is the key: Cooking eggs to a final temperature of 160 degrees Fahrenheit or holding them at a temperature of 140 degrees Fahrenheit for 3 1/2 minutes will kill salmonella bacteria.