What is the process by which bone is broken down and then rebuilt called?

A. Vision changes in older adults, such as presbyopia, cataracts, or macular degeneration, are caused by age-related alterations in the eyes themselves, not by saliva production. Vision decline is independent of oral secretions.

B. Smell depends on olfactory receptors in the nasal cavity. Although aging can reduce the sensitivity of smell receptors (hyposmia), this is unrelated to saliva levels, so decreased saliva does not impair olfactory function.

C. Hearing loss, often due to presbycusis or damage to inner ear structures, is not influenced by saliva production. The auditory system, not the oral cavity, governs hearing function.

D. Taste is directly affected by saliva production. Saliva is essential for dissolving food particles so that taste buds on the tongue can detect flavors. In older adults, reduced saliva production, called xerostomia or dry mouth, can diminish perception of sweet, salty, sour, and bitter flavors, make chewing and swallowing more difficult, increase the risk of dental caries and oral infections, and reduce appetite, potentially leading to nutritional deficiencies. Because taste and flavor perception depend on adequate saliva, a decrease can significantly affect food enjoyment and nutritional intake. Managing dry mouth with hydration, sugar-free gum, saliva substitutes, and proper oral hygiene helps maintain taste perception and overall nutrition.

A. Vitamin E is present in breast milk at levels generally sufficient for healthy, full-term infants. It functions as an antioxidant, protecting cell membranes from oxidative damage. Deficiency is very rare in breastfed infants unless there is a fat malabsorption disorder or premature birth with very low birth weight, as these conditions limit fat-soluble vitamin absorption. Therefore, routine supplementation is not required for most term infants.

B. Vitamin C is water-soluble and abundant in breast milk when the lactating mother has an adequate diet. It supports collagen formation, immune function, and antioxidant activity. Deficiency in breastfed infants is uncommon unless the mother’s intake is severely inadequate, which is rare in most populations.

C. Calcium is a critical mineral for bone and teeth development, and breast milk generally contains sufficient calcium to meet the needs of full-term infants. The infant’s calcium requirements are met even if maternal intake is moderate because the mammary gland actively regulates calcium content in milk. Deficiency in calcium is therefore not a common concern in healthy, exclusively breastfed infants.

D. Vitamin D is naturally present in breast milk in very low amounts, insufficient to meet the infant’s needs, particularly if sunlight exposure is limited. Vitamin D is essential for calcium absorption and bone mineralization. Without supplementation, breastfed infants are at risk for rickets, delayed bone growth, and skeletal deformities. Health organizations, such as the American Academy of Pediatrics, recommend daily vitamin D supplementation (typically 400 IU/day) for all exclusively breastfed infants.