( CM ) - Animal activists at People For The Ethical Treatment Of Animals (PETA) are urging BRITNEY SPEARS' parents to overhaul the troubled singer's eating habits - because her ongoing mental health issues could be linked to her diet. PETA president Ingrid Newkirk has written to Jamie and Lynne Spears, suggesting the Toxic hitmaker's reported schizophrenia or bipolar disorders could be related to her meat and dairy intake. Newkirk writes, "We have heard that Britney asked for ice-cream while she was in the hospital. There could, in fact, be a connection between her diet and her mental-health problems. "Numerous reports indicate that in bipolar patients who have hidden dairy sensitivities (a fairly common condition), the disorder can worsen if the patient consumes dairy products. "And a significant body of research-including evidence cited by the Centers for Disease Control and Prevention-has linked parasites that are often found in undercooked meat (Toxoplasma gondii) to the development of schizophrenia." The PETA president adds, "While the medical link between mental illness and meat and dairy consumption is still evolving, there is no doubt that eating animal products is a major factor in causing other diseases."