DEAR ABBY: I am a student at a chiropractic college in Portland, Ore. When I told a friend that my microbiology instructor has a Ph.D. in microbiology, a master's degree in public health and has worked in Malaysia as an expert in tropical diseases, my friend said, "Why is someone with such outstanding credentials teaching at that quack medical school you go to?"

Abby, this brought home a popular misconception many people have about chiropractors. We take many of the same courses that are taught in medical school - with less emphasis on drugs and biochemistry, and more emphasis on nutrition, biomechanics, the nervous system and radiology.I'm learning to recognize disease and dysfunction, to treat what's appropriate for chiropractic care and refer what is not. I must go to school for four years and pass the national and state boards before I can practice.

It bothers me to work this hard, learn so much and dedicate my life to patient care, and know that about half the population thinks I'm an untrained quack with a one-year degree! Please let people know that we are competent, well-trained, and we care. - CAROLYN MCMAKIN, PORTLAND

DEAR CAROLYN: I called Dr. Charles F. Downing, president of the American Chiropractic Association, who graciously allowed me to fax your letter to him. He then faxed me the following letter:

DEAR ABBY: Unfortunately, Carolyn's experience is not uncommon. There are many people who remain misinformed about chiropractors and their legitimate role in the health-care system.

Worldwide studies by governmental commissions and independent researchers have demonstrated the health and cost benefits of chiropractic care. Chiropractic colleges can attract highly qualified science faculty like Carolyn's microbiology instructor because the faculty know the facts and want to help chiropractic students become competent, scientifically trained doctors of chiropractic.

Recent scientific studies continue to validate the superiority of chiropractic over traditional medicine in the treatment of CERTAIN CONDITIONS - most recently, a study published in the July 1990 issue of the British Medical Journal titled "Low Back Pain of Mechanical Origin," by Meade, Dyer, Browne, Townsend and Frank.

The exams administered to doctors of chiropractic are some of the most stringent anywhere as they relate to human health and biomechanics. To the degree they focus on specific aspects of health - the nervous system and its relationship to proper functions of the body - they are known to be the most stringent compared to other examinations.

To be informed is to be enlightened. The American Chiropractic Association encourages citizens of the world to discover the truth behind the effectiveness and affordability of this health-care alternative as a mainstream option. Please feel free to write to the American Chiropractic Association for more information: 1701 Clarendon Blvd., Arlington, VA 22209. Please enclose a self-addressed, stamped envelope.

People are eating them up! For Abby's favorite recipes, send a long, business-size, self-addressed envelope, plus check or money order for $3.95 ($4.50 in Canada) to: Dear Abby, Cookbooklet, P.O. Box 447, Mount Morris, IL 61054. (Postage is included.)