Sept. 13, 2011 -- Georgia's Supreme Court has sentenced an Atlanta couple to life in prison for starving its infant son, rejecting claims by the defense that vegan rules were to blame.

Six-week-old Crown Shakur weighed 3½ pounds when he died in 2004 from extreme malnourishment or starvation. His parents, Jade Sanders and Lamont Thomas, were convicted Monday of malice murder, felony murder, involuntary manslaughter and cruelty to children.

"No matter how many times they want to say, 'We're vegans, we're vegetarians,' that's not the issue in this case," prosecutor Chuck Boring told the court. "The child died because he was not fed. Period."

Bottles of soy milk -- not formula -- and apple juice as well as a dirty, rancid baby bottle were found during a police search of the couple's Buckhead apartment.

"This was not a well-nourished child on any level, but it sounds like this had more to do with not getting enough calories or protein overall than a vegan diet," said Keith Ayoob, director of the Rose R. Kennedy Center Nutrition Clinic at Albert Einstein College of Medicine in New York. "Veganism does not starve an infant."

Babies need at least 10 ounces of liquid food per day, with the healthy range spanning from 16 to 30 ounces, according to Dr. Ira Rubin, a private practice pediatrician in Naperville, Ill.

"Since the baby lost around half of its weight, it sounds like they certainly did not feed the infant enough volume," Rubin said.

The American Academy of Pediatrics recommends that babies breastfeed for the first six months -- a practice that, if manageable, conforms to vegan ideals. And for vegan women who can't or choose not to breastfeed, soy milk-based formulas are available. Soy milk, however, is not a substitute for fortified formula, Rubin said.

The prosecutors also argued the couple neglected their child by not seeking medical attention as his body wasted away.

"To me, even if the parents did not understand what to feed the baby, all they needed to do is ask the nurses or doctors at the hospital they delivered at, or even go back to their doctor's office to ask why the baby is losing so much weight," Rubin said.

As more adults adopt the vegan diet, more babies and children are inheriting it. Alicia Silverstone's 3-month-old baby, Blu, is reportedly vegan. Natalie Portman dropped her vegan diet during pregnancy in favor of a more flexible vegetarian diet.

Experts say the vegan diet can be complete and nutritious for the whole family, as long as it contains enough protein, calcium and vitamins D and B12. But fussy young eaters can complicate things.

"Any time you remove a food you place a bigger burden on the remaining foods to pick up the slack," said Ayoob. "I recommend that vegan parents, in the early years, remain flexible. Let philosophy take second string to the child's nutritional needs at least until they're older and can make decisions for themselves."

The Associated Press contributed to this report.