Mexico is struggling to come to grips with a nutritional problem that experts say affects half the nation's population. ''Millions of Mexicans eat the same thing everyday - tortillas, beans, and sometimes vegetables and fruits,'' says Hector Bourges, a specialist with the Mexican Nutrition Institute. The result, he says, is an improperly balanced diet. The institute concludes that 35 million Mexicans are malnourished.
In an effort to swing the nation toward better eating, President Miguel de la Madrid Hurtado has launched a food program that would try to make more foods available to Mexicans and to raise the nation's level of agricultural production.
The program is also aimed at making the country self-sufficient in food production. Until 1970, Mexico was one of the few Latin American countries whose agricultural output kept pace with, and at times surpassed, population growth. But since then, production has dropped and this country which once exported grain began to import it.
''We cannot permit the country to fall into a dangerous food dependency'' the President said in a recent speech.
If the problem of widespread malnutrition, especially among children, is not solved, he added, ''we will not only restrict personal development but we will also sentence the country to a sustained situation of disadvantage and backwardness.''
There are many factors behind Mexico's food problem:
* High population growth. The Mexican population jumped from 50 million in 1970 to 70 million 10 years later, straining government resources.
* Falling agricultural production. After 1970, there was a dramatic falloff as a result of adverse pricing policies, a credit system that favored cash crops , inflation, and drought.
* Distribution problems. There are about 100,000 Mexican villages with a population of 2,500 or less. Many of them ''cannot receive foodstuffs because of the distance and isolation,'' Mr. Bourges says. Distribution is perhaps the main culprit of Mexico's nutritional problem, say many of the nation's experts.
* Habits, superstition, poor hygiene. ''In the countryside, farmers won't eat eggs because they claim eggs are 'heavy.' They'll drink milk or water without boiling it and cook on the ground,' '' says Arturo Soda, an agricultural expert with the National Basic Commodities Agency, a government organization that sells subsidized food to low-income Mexicans.
Malnutrition is not a recent phenomenon in Mexico, and de la Madrid's is not the first government effort to deal with the food problem.
De la Madrid's food program has goals similar to that of former President Jose Lopez Portillo. But a key distinguishing factor is that the current President's program promises to pay farmers more for their produce. That feature is viewed with approval by some observers, who say it will be a powerful incentive to farmers to produce larger quantities of food. In the last six months, producer prices have already more than doubled.
But critics say the new program is vague and that it reads more like a declaration of intent than a list of concrete steps toward higher production. They also object that it has no time frame. They also fear it will get bogged down in red tape.
Experts are split on whether de la Madrid's plan will fare better than previous efforts.
''The (de la Madrid plan) will only increase food problems by wasting money with the creation of new plans and the cancellation of old ones,'' says Lucia Alvarez Moss, a researcher at the Institute for Economic Investigations.