IF IT'S TOO MUCH trouble to teach children to eat nutritious, healthful food, take the junk they love and "nutrify" it.

That's the if-you-can't lick-'em-join-'em rationale which underlies Vicki Lansky's cookbook, The Taming of the C.A.N.D.Y. [Continously Advertised, Nutritionally Deficient, Yummies] Monster," or "How to Get Your Kid to Eat Less Sugary, Salty 'Junk Food' Without Sacrificing Convenience or Good Taste." It's the same rationale which sanctions vitamin and mineral-fortified fat and sugar-laden dough-nuts and cupcakes for the school breakfast program and turns cereals into candy-coated vitamin pills.

Lansky's solutions certainly require a lot less backbone than saying "No" when your child lies down in between the candy and sugar-coated cereal aisles and screams for a box of Cookie Crisps (that's one of those nutrient-fortified so-called cereals which looks and tastes like a cookie) or a package of M&Ms. Some people would call her suggestions realistic; others, a cop-out.

The author's recipes for alternative food, much of which would be just plain "junk" if it came from the store instead of being made at home, pick up where they left off in her first book, Feed Me! I'm Yours. Some of the treats in both books actually have nutritious ingredients added; many do not, such as Ice Pops made with Jell-O, Kool-Aid and sugar (or artificial sweetener); Marshmallow Popcorn Balls made with more Jell-O, plus marshmallows, popcorn and butter. General Foods must have done the shimmy on its empty Jell-O boxes when the first book was published.

In the latest book some of Lansky's general rules for curbing sugar and salt comsumption are nutritionally sound. She suggests reducing the amount of sugar in recipes, reliance on packaged foods and particularly the number of C.A.N.D.Y. items in the house. She says desserts should be treated as an occasion, not an everyday occurrence and recommends discussing television ads with children to "explain the company's motivation and possible half-truths mentioned."

She also suggests using saccharine instead of sugar, an alternative open to heated debate. Lansky acknowledges that saccharine may be bad, but never elaborates. However, she plays scientist and offers the gratuitous information than eating a little saccharine is okay, it just might not be safe in large quantities.

On the subject of salt, Lansky says that it should be used only in recipes where it is chemically essential, i.e., with yeast.

Her idea of keeping healthful snack foods readily available - a fruit plate on the table, nuts in a jar, cut-up vegetables and pieces of cheese in the refrigerator - would win plaudits from everyone. It's when the author gets down to specifics that she runs afoul of her own general rules.

Lansky notes that ham, bacon, sausage and hot dogs contain a lot of salt and in her first book even mentions that these and other processed meats contain "nitrates" (she means nitrites) which should "be served in moderation as some experts question the safety of nitrates [sic]." Yet her list of 19 appropriate meats for year-old babies, which begins with crisp bacon, contains nine meats which are not only preserved with sodium nitrate, but are high in salt.

Recipes using similar meats are scattered throughout the latest book which also offers directions for Candy Cookies made with M&Ms, popsicles made with Hawaiian Punch, sno-cones made with artificial coloring plus sugar, honey or corn syrup, and granola bars made with butterscotch chips and grape jelly. Out of more than 100 recipes, at least 75 contain sweetener in one form or another.

In some recipes Lansky makes an attempt to beef up the nutritional value of homemade sweets by changing around the ingredients. Putting wheat germ in cookies, making "candied" apples with honey instead of parabolized sugar. Substituting carob for chocolate in a cake may make a parent feel less guilty about feeding a child sweets, but it won't do a thing to teach the child what's wrong with consuming large quantities of them. And it's a little difficult for children to understand why it's okay to eat those home-made M&M cookies but it's very naughty to gulp down a handful of M&M right out of the bag.

Indeed, what makes Lansky's Whipped Cream Graham Cracker Cake, created by spreading sweetened whipped cream over and between layers of store-bought graham crackers, nutritionally superior to those Continuously Advertised, Nutritionally Deficient Yummies?

Lansky is guilty of some pretty fuzzy-headed thinking and the book is most successful making a mockery out of the title. When Lansky gets through in the kitchen, homemade isn't necessarily more nutritious at all.