Health
Vitamin D: Key Facts for Healthy Aging
Health Points
- Vitamin D supports bones, immune system, and healthy aging.
- Sunlight, certain foods, and supplements provide vitamin D.
- Recommended daily intake differs by age and lifestyle.
Vitamin D is vital for helping the body absorb calcium, which keeps bones strong as we age. This nutrient also acts as an antioxidant, supporting immune health and potentially slowing cellular aging.
A recent study indicates that sufficient vitamin D may decrease biological aging and reduce the risk of age-linked diseases.
What is Vitamin D?
Vitamin D, or calciferol, is a fat-soluble vitamin that helps the body absorb calcium from food.
“Vitamin D has two main responsibilities: helping calcium reach your bones, which keeps them strong, and supporting your immune system so it can fight off infections,” says Julia Zumpano, registered dietitian.
This nutrient is also important for nerve, muscle, and brain function, playing a key role in cell growth.
Dr. Natalie Azar says, “It’s very important in cell growth.”
There are two main forms: D3, from sun exposure and animal foods; and D2, from plant sources and fortified foods. Both are stored in fat cells until converted to their active form.
Vitamin D Benefits
“Vitamin D is very important in the body because it contributes to the bone health, musculoskeletal health, immune function and many functions,” explains Dr. Julia Adamian, internist.
During childhood, it prevents rickets, while in adults, it works with calcium to prevent osteoporosis, according to Dr. Azar.
Vitamin D also helps reduce inflammation, supports heart and brain health, and aids glucose regulation.
Research published in May 2025 links adequate vitamin D to longer telomeres—the chromosome caps that influence biological aging—helping lower the risk of age-related illness.
How Much Vitamin D Per Day?
Recommendations vary by age, per expert guidance:
- Children (1–18 years): 15 mcg (600 IU)
- Adults (18–70 years): 15 mcg (600 IU)
- Over 70: 20 mcg (800 IU)
Where Does Vitamin D Come From?
Sunlight helps the body make vitamin D when skin is exposed to UVB rays. As little as five to 30 minutes of midday sun several times weekly can be enough for most people, per the NIH.
According to Dr. Adamian, “The production of the vitamin D is activated in the skin through contact with UVB rays.”
People using sunscreen can still produce vitamin D with sun exposure, though in smaller amounts.
Foods naturally rich in vitamin D include cod liver oil, salmon, trout, sardines, and UV-exposed mushrooms. Eggs, beef liver, and cheese offer some D3, while many foods—like milk, fortified juices, and cereals—contain added vitamin D.
Nutritionist Joy Bauer shares that most Americans get vitamin D from fortified food choices.
Supplements and Who Needs Them
Supplements often contain D2 or D3, with D3 usually boosting vitamin D levels more effectively.
“It is tough to get enough from diet alone, so it’s usually a combination of all these,” notes Dr. Adamian.
Most healthy adults can reach recommended levels through sun, food, or a daily multivitamin, but some may require additional supplementation, especially if they get little sunlight or have restricted diets.
Those who don’t have enough vitamin D from sun or food may become deficient, resulting in symptoms like bone pain, muscle weakness, or fatigue, according to Dr. Adamian.
Chat with your healthcare provider to determine your vitamin D status and the best way to support your health as you age.
