Therefore, the presence of such ingredients may cause blindness, cancer, and may also affect the immune system. (usbones.com)
Low levels of vitamin A can also negatively affect your immune system and cause serious illnesses and / or death. (foodpyramid.com)
A lack of protein in the diet can adversely affect the immune system as shown, and specifically have a negative impact on the T cell system. (aminoacidstudies.org)