Taking a multivitamin with vitamin D can help improve bone health and overall wellbeing. The recommended daily amount of vitamin D for children up to 12 months old is 400 international units (IU), 600 IU for people aged 1 to 70, and 800 IU for those over 70 years old. According to Mayo Clinic, adults should receive at least 600 IU daily. However, taking a vitamin D supplement of 1000 to 2000 IU per day is generally safe and may provide additional health benefits.
Although there are no guidelines for controlling the level of vitamin D in the blood, it may be beneficial for people with osteoporosis or other health conditions. If this is the case, it is best to consult a healthcare provider. Children over 1 year old and adults need 10 micrograms of vitamin D a day, including pregnant and breastfeeding women and those at risk of deficiency. Diets low in vitamin D are more common in people who have a milk allergy or lactose intolerance and those who follow an ovovegetarian or vegan diet.
Vitamin D is also produced endogenously when ultraviolet (UV) rays from sunlight hit the skin and cause its synthesis. No study has evaluated whether vitamin D supplements can benefit people receiving medical care for clinical depression who have low or deficient levels of 25 (OH) and D and who are taking antidepressant medications. Low levels of vitamin D are also associated with falls, multiple sclerosis, rheumatoid arthritis, chronic pain, diabetes, high blood pressure, cardiovascular disease and some types of cancer. The USPSTF reviewed seven published studies on the effects of vitamin D supplementation (two of which also included calcium supplements) on the risk of falls in community-dwelling adults aged 65 and over who did not have osteoporosis or vitamin D deficiency.
Prostate cancer research conducted to date provides conflicting evidence as to whether levels of 25 (OH), D are associated with the development of prostate cancer. In addition, certain health conditions affecting the gastrointestinal tract may decrease the absorption of vitamin D and predispose to low levels of vitamin D in the blood. Following the lowest recommendations, many adults don't get the amount of vitamin D they should. In addition to having a higher risk of vitamin D deficiency, people with these conditions may not consume certain foods, such as dairy products (many of which are fortified with vitamin D), or may only consume small amounts of these foods. In a recent clinical trial, 78 frail and nearly frail adults aged 65 and over were randomly assigned to receive 20 mcg (800 IU) of vitamin D3, 10 mcg of 25 (OH), D, or placebo daily for 6 months.
There were no substantial differences between the groups in the incidence of fractures by race, ethnicity, BMI, age, baseline levels of 25 (OH) and D, nor whether participants took calcium supplements, were at high risk of fracture, or had a history of fractures due to frailty. Vitamin D deficiency or insufficiency did not increase the risk of prostate cancer, and higher levels of 25 (OH) and D were not associated with a lower risk. The government's advice is that everyone should consider taking a daily vitamin D supplement during fall and winter months.