Newborn infants can be quite demanding. If they could talk, they might tell you that it is due to their challenging nutrient needs. The average healthy baby triples its weight during the first year of life. That requires plenty of calories and essential nutrients.

All of the major components of the body go through rapid development during this first year. Anything that compromises this development can have devastating, lifelong effects.

The breast-fed infant of a healthy mother can thrive well on nothing but breast milk for four to six months. The nutrient content of breast milk, however, can be affected by the mother's diet and nutritional status.

Vitamin B-12 is a nutrient of special concern due to its essential role in brain and nerve development. If a mother is deficient in B-12, her milk will not meet the baby's B-12 needs and the baby's brain and nerve development can be irreversibly damaged.

  Question: What can cause vitamin B-12 deficiency in a mother?

Answer: A recent article by Daphna Dror and Lindsay Allen at the University of California, Davis, cites two main causes. Deficiency can develop when consumption of animal foods has been low for an extended period or due to poor absorption of vitamin B-12 caused by intestinal problems. Strict vegetarians or vegans are at high risk for deficiency since B-12 is lacking in plant foods. Also, women who have had gastric bypass surgery have impaired B-12 absorption and will develop B-12 deficiency without proper supplementation.

Because many Americans eat too much meat and other animal products, public health messages encourage eating less of these foods. When people then take these recommendations to the extreme and completely avoid animal foods, they can become deficient in specific essential nutrients like B-12. Obtaining B-12 in fortified foods and supplements can prevent this.

  Q: What are the symptoms of B-12 deficiency in infants?

A: Dror and Allen found that B-12 deficient infants often are resistant to weaning and refuse to eat foods, preferring only to breast-feed. Reduced muscle tone and weakness are other signs, along with tiredness, irritability, not smiling and even convulsions in some cases. Overall development is slowed, and the children are usually small for their age.

Chances for the baby's recovery depend on the extent and duration of the deficiency. B-12 treatment shows rapid benefits, but the researchers found that about half of the babies of B-12-deficient vegan mothers had long-term impairments that may have caused permanent damage.