Vitamins are micronutrients required in small quantities to regulate metabolism and support normal physiological function. While the body can synthesize some vitamins, most must be obtained through food. The timing of supplementation depends entirely on the individual’s life stage, as nutritional demands change significantly from birth through adulthood. Although a balanced diet is the preferred source, distinct periods of life—such as accelerated growth or physiological change—may necessitate supplementation.
Infancy and Early Childhood Needs
Supplementation begins immediately at birth with the administration of Vitamin K. Newborns have very low stores of this vitamin, which is necessary for blood-clotting factors. A single intramuscular dose of 0.5 to 1.0 mg is standard practice to prevent Vitamin K Deficiency Bleeding (VKDB). This prophylactic intervention is a mandatory start to supplementation, regardless of whether the infant is breastfed or formula-fed.
Beyond the newborn period, Vitamin D becomes the most commonly recommended supplement for infants, especially those who are exclusively breastfed. Human milk often contains insufficient Vitamin D, which is necessary for calcium absorption and bone development. Pediatric guidelines recommend a daily supplement of 8.5 to 10 micrograms of Vitamin D for all breastfed babies from birth.
As infants transition to solid foods around six months of age, iron stores built up during gestation begin to deplete. Iron is essential for cognitive development and preventing anemia. Its need is particularly high during the first two years of life. Supplementation with iron or the introduction of iron-fortified cereals is often necessary, especially if the infant does not consume iron-rich animal products.
Vitamins During School-Age and Adolescence
The period from age six through the teenage years shifts the focus to addressing the demands of rapid growth and evolving dietary habits. Peak bone mass accumulation occurs during adolescence, requiring elevated intake of both Calcium and Vitamin D. Calcium intake recommendations peak at 1,300 mg per day during the growth spurt to ensure skeletal development and reduce the risk of osteoporosis.
For both genders, increased lean body mass and blood volume necessitate higher Iron intake during the teenage years. Adolescent females face an increased risk of deficiency with the onset of menstruation. They often require up to 15 to 18 mg of iron daily to compensate for monthly blood loss. While a well-rounded diet should ideally meet these increased requirements, supplementation may be employed if a teen’s diet is unbalanced, restricted, or lacking in fortified foods.
Adult Supplementation: Lifestyle and Targeted Needs
Routine, broad-spectrum supplementation is often unnecessary for the general adult population if a diverse diet is consumed. However, specific physiological states and lifestyle choices create targeted needs. A primary instance is the requirement for Folic Acid (Vitamin B9) in women capable of becoming pregnant. Supplementation with 400 micrograms daily is recommended before conception and during early pregnancy to significantly lower the risk of neural tube defects.
Voluntary dietary choices also mandate supplementation, such as Vitamin B12 for those following a plant-based or vegan diet. Since B12 is almost exclusively found in animal products, those who restrict meat and dairy must obtain the nutrient from fortified foods or a supplement to prevent nerve damage and anemia. Certain medications, such as the common diabetes drug Metformin, can also interfere with the absorption of B12, requiring a specific supplement plan for affected patients.
Vitamin D status is a common concern for adults, especially those who live at northern latitudes or use strict sun protection. Because sunlight exposure is the primary source of Vitamin D synthesis, a supplement is often the most reliable way to maintain adequate levels.
Nutritional Considerations for Older Adults
For older adults (generally over 65), the focus shifts to compensating for age-related changes in nutrient absorption and utilization. Reduced capacity to synthesize Vitamin D in the skin (up to four times less efficient), combined with less time spent outdoors, makes supplementation almost universally recommended. The recommended daily intake of Vitamin D increases to 800 IU per day after age 70 to support bone density.
Vitamin B12 also becomes a concern due to changes in digestive physiology. Atrophic gastritis, a common age-related condition, reduces stomach acid production, which is necessary to separate B12 from food proteins for absorption. Due to this malabsorption issue, up to 30% of older adults may struggle to absorb B12 from food sources. Therefore, healthcare providers often recommend older adults obtain B12 from readily absorbable supplements or fortified foods.