Takeaways
- Vitamin D supports bone health and immune function
- Sunlight exposure produces vitamin D in the skin
- Fatty fish and fortified foods provide dietary vitamin D
- Many people need supplements to meet vitamin D needs
- Vitamin D deficiency is common but often undiagnosed
- Regular testing helps maintain optimal vitamin D levels
What is Vitamin D?
Vitamin D is a crucial nutrient that dissolves in fat and is vital for overall health.[1] Our bodies can create vitamin D when our skin is exposed to sunlight, and we can also obtain it from certain foods and dietary supplements.[2]
Vitamin D helps the body absorb calcium, which is necessary for building and maintaining strong bones.[3] Furthermore, it plays a role in supporting the immune system and may also influence mood.[4]
There are two primary types of vitamin D: Vitamin D2 (ergocalciferol), which is derived from plants, and Vitamin D3 (cholecalciferol), which is produced in animal tissues and human skin.[5]
Sources of Vitamin D
Sunlight
Our skin produces vitamin D when it’s exposed to UVB rays from sunlight. This process begins when sunlight converts a type of cholesterol in our skin to vitamin D3.[6]
Several factors impact the amount of vitamin D our skin produces through sun exposure:
- Time of day: Midday sun produces more vitamin D
- Season: Summer sun is stronger than winter sun
- Latitude: Places closer to the equator get more direct sunlight
- Skin pigmentation: Darker skin needs more sun exposure
- Age: Older skin produces less vitamin D
- Sunscreen use: SPF 30 reduces vitamin D production by 95%
Individuals with light skin tones typically need 10 to 30 minutes of midday sun exposure two to three times per week. People with darker skin tones may require three to six times more exposure to achieve the same vitamin D production.[7]
Dietary Sources
Very few foods naturally contain significant amounts of vitamin D. The best dietary sources include:
- Fatty fish like salmon, tuna, and mackerel
- Fish liver oils
- Egg yolks
- Beef liver
- Cheese
Many foods are now fortified with added vitamin D. These often include:
- Milk and plant-based milk alternatives
- Orange juice
- Breakfast cereals
- Yogurt
- Margarine
Here’s a comparison showing the vitamin D content found in some common foods:
| Food | Serving Size | Vitamin D (IU) |
|---|---|---|
| Cod liver oil | 1 tablespoon | 1360 |
| Salmon, cooked | 3 ounces | 447 |
| Tuna, canned | 3 ounces | 154 |
| Fortified milk | 1 cup | 115-124 |
| Fortified yogurt | 6 ounces | 80 |
| Egg yolk | 1 large | 41 |
Fortified foods are helpful in boosting vitamin D intake, particularly for individuals who have limited sun exposure or dietary restrictions.[8]
Supplements
Vitamin D supplements come in two forms: D2 (ergocalciferol) and D3 (cholecalciferol). Both can raise vitamin D levels in the blood, but D3 is often considered more effective.[9]
Supplements offer a dependable way to meet vitamin D needs. They are especially beneficial for people with limited sun exposure or dietary sources of this nutrient.[10]
Benefits of using vitamin D supplements:
- Consistent dosage
- Not affected by weather or season
- Useful for people with dietary restrictions
Drawbacks of using vitamin D supplements:
- Possible interactions with medications
- Risk of excessive intake
- Cost over time
Steps to consider when choosing a vitamin D supplement:
- Consult a healthcare provider
- Check the form (D2 or D3)
- Consider dosage based on your needs
- Look for third-party testing
- Choose a reputable brand
Vitamin D Deficiency
Vitamin D deficiency occurs when blood levels drop below 20 ng/mL (50 nmol/L). This is a common issue, impacting about 1 billion individuals worldwide.[11]
Risk factors that can increase the likelihood of vitamin D deficiency include:
- Limited sun exposure
- Dark skin pigmentation
- Obesity
- Older age
- Malabsorption disorders
- Certain medications
Common symptoms that may indicate a vitamin D deficiency include:
- Fatigue
- Bone pain
- Muscle weakness
- Mood changes
- Frequent infections
At-Risk Groups
Some populations have an increased risk of vitamin D deficiency:
- Older adults: Aging skin produces less vitamin D
- People with dark skin: Melanin reduces vitamin D production
- Individuals with limited sun exposure: Indoor workers, those who cover up outdoors
- People with obesity: Vitamin D can get trapped in body fat
- Those with digestive issues: Conditions like Crohn’s disease affect absorption
Here’s a comparison of how much vitamin D different groups of people need:
| Group | Recommended Daily Intake (IU) |
|---|---|
| Infants 0-12 months | 400 |
| Children 1-18 years | 600 |
| Adults 19-70 years | 600 |
| Adults 71+ years | 800 |
| Pregnant/breastfeeding women | 600 |
These recommendations are based on minimal sun exposure. Some experts suggest that higher vitamin D intakes are needed for optimal health.[12]
Health Benefits of Vitamin D
Bone Health
Vitamin D is essential for calcium absorption and the building of strong bones. Without enough vitamin D, the body can’t effectively use calcium from the diet.[13]
Adequate vitamin D intake supports:
- Proper bone formation in children
- Maintenance of bone density in adults
- Prevention of osteoporosis and fractures in older adults
Research has shown that vitamin D supplements can lower the risk of falls and bone fractures in older adults.[14]
Immune Function
Vitamin D supports our immune system through a number of different mechanisms:
- Enhances the function of immune cells
- Reduces inflammation
- May help prevent autoimmune diseases
Studies suggest that vitamin D may reduce the risk of respiratory infections. A study in 2017 found that vitamin D supplements lowered the risk of acute respiratory infections by 12%.[15]
Mood and Mental Health
Growing research connects vitamin D with mood and mental well-being. Low levels of vitamin D are associated with depression, especially in older adults.[16]
Vitamin D receptors are present in areas of the brain that control mood. This indicates that vitamin D may directly impact brain function and mental health.[17]
Some studies indicate that vitamin D supplements can improve depression symptoms. However, further research is needed to fully understand this connection.[18]
Other Potential Benefits
Researchers are investigating vitamin D’s potential role in various health conditions. Current areas of interest include:
- Heart disease prevention
- Cancer risk reduction
- Diabetes management
- Cognitive function
- Autoimmune disease prevention
While initial results are promising, additional studies are necessary to confirm these potential benefits.
Recommended Intake
The Recommended Dietary Allowance (RDA) for vitamin D varies with age and life stage. These guidelines are designed to meet the needs of 97-98% of healthy people.[19]
Here are the current RDAs for vitamin D:
| Age Group | RDA (IU/day) |
|---|---|
| 0-12 months | 400 |
| 1-70 years | 600 |
| 71+ years | 800 |
| Pregnant/breastfeeding | 600 |
There is an ongoing debate about what the optimal levels of vitamin D should be. Some experts suggest that the current recommendations are too low for ideal health.[20]
The Endocrine Society suggests higher vitamin D intakes:
- 400-1000 IU/day for children
- 1500-2000 IU/day for adults
These increased recommendations aim to maintain blood levels above 30 ng/mL (75 nmol/L), which some consider optimal for overall health.[21]
Vitamin D Testing
Blood tests can measure vitamin D levels in the body. The most common test measures 25-hydroxyvitamin D, which is the primary form of vitamin D circulating in the blood.[22]
Here’s what different blood levels of vitamin D mean:
- Deficient: Less than 20 ng/mL (50 nmol/L)
- Insufficient: 21-29 ng/mL (52-72 nmol/L)
- Sufficient: 30-50 ng/mL (75-125 nmol/L)
- High: Greater than 50 ng/mL (125 nmol/L)
Some experts believe that vitamin D levels above 30 ng/mL are optimal for good overall health.[23]
Steps to get a vitamin D test:
- Consult your healthcare provider
- Schedule a blood draw
- Fast for 4-8 hours before the test
- Get your blood drawn
- Wait for results (usually 1-3 days)
- Discuss results with your provider
Regular testing helps maintain ideal vitamin D levels. How often you need to be tested depends on your risk factors and initial test results.[24]
Risks of Excessive Vitamin D
While vitamin D deficiency is common, excessive intake can be harmful. Vitamin D toxicity is rare, but it is possible, especially from high-dose supplements.[25]
Symptoms of vitamin D toxicity include:
- Nausea and vomiting
- Poor appetite and weight loss
- Constipation
- Weakness
- Confusion
- Kidney problems
Factors that may increase the risk of vitamin D toxicity include:
- Taking very high-dose supplements
- Overuse of tanning beds
- Certain medical conditions
- Some medications
The safe upper limit for vitamin D intake is 4,000 IU per day for adults. However, higher doses may be safe under medical supervision.[26]
Vitamin D and Special Populations
Pregnancy and Breastfeeding
Vitamin D is crucial during pregnancy and breastfeeding. It helps with fetal bone development and may lower the risk of certain pregnancy complications.[27]
Pregnant and breastfeeding women need 600 IU of vitamin D daily. Some experts recommend higher doses, especially for women who have a higher risk of deficiency.[28]
Benefits of adequate vitamin D during pregnancy include:
- Reduced risk of preeclampsia
- Lower rates of gestational diabetes
- Decreased risk of low birth weight
Breastfed infants may need vitamin D supplements because breast milk often doesn’t provide enough of this vitamin.[29]
Infants and Children
Vitamin D is essential for bone development in babies and children. It helps prevent rickets, a condition causing soft, weak bones.[30]
The American Academy of Pediatrics recommends:
- 400 IU/day for infants up to 12 months
- 600 IU/day for children 1-18 years
Breastfed babies should receive vitamin D supplements from the first few days of life. Formula-fed babies may not require supplements if they consume at least 32 ounces of fortified formula daily.[31]
Older Adults
Older adults have a higher risk of vitamin D deficiency because of:
- Decreased sun exposure
- Less efficient skin production of vitamin D
- Possible dietary changes
Adults over 70 need 800 IU of vitamin D daily. Some individuals may need higher doses to maintain optimal levels.[32]
Strategies for maintaining vitamin D levels in older adults:
- Regular sun exposure (with skin cancer precautions)
- Consumption of vitamin D-rich foods
- Vitamin D supplements as recommended by a healthcare provider
- Regular physical activity, especially outdoors
Adequate vitamin D intake in older adults can help prevent falls and fractures, which helps maintain independence and a good quality of life.[33]
Vitamin D and Other Nutrients
Vitamin D interacts with several other nutrients in the body. These interactions can affect how well our bodies use vitamin D.[34]
Here’s an overview of key nutrient interactions:
| Nutrient | Interaction with Vitamin D |
|---|---|
| Calcium | Vitamin D enhances calcium absorption |
| Magnesium | Needed for vitamin D metabolism |
| Vitamin K | Works with vitamin D for bone health |
| Vitamin A | May compete with vitamin D for absorption |
| Zinc | Helps activate vitamin D in the body |
Maintaining a balance of these nutrients is essential for overall health. A varied diet will usually provide the right mix of nutrients. However, some people may need supplements to achieve balance.
Seasonal Variations in Vitamin D Status
Vitamin D levels often change with the seasons, especially in areas farther from the equator.[35]
During the summer, sun exposure boosts vitamin D production. During the winter, shorter days and more time indoors can result in lower levels.[36]
Strategies for maintaining year-round vitamin D levels:
- Eat more vitamin D-rich foods in winter
- Consider supplements during low-sun months
- Spend time outdoors in summer (with sun protection)
- Get vitamin D levels checked in late winter or early spring
Tips for getting enough vitamin D in winter:
- Eat fatty fish 2-3 times per week
- Choose vitamin D-fortified foods
- Consider a vitamin D supplement
- Use a light therapy box (doesn’t produce vitamin D but may help with mood)
- Exercise outdoors when possible, even on cloudy days
Paying attention to vitamin D intake can help prevent seasonal deficiencies.[37]
FAQ
Can you get enough vitamin D from food alone?
How much sun exposure do you need for vitamin D?
What are the signs of low vitamin D?
Can you take too much vitamin D?
Does vitamin D help with weight loss?
Is it better to take vitamin D every day or once a week?
Conclusion
Vitamin D is essential for good health, from building strong bones to supporting the immune system. While our bodies can create vitamin D through sunlight exposure, many people don’t get enough sunlight to meet their needs.
Diet can help, but very few foods are naturally rich in vitamin D. Fortified foods and supplements provide reliable ways to increase vitamin D intake.
Vitamin D deficiency is common but often goes unnoticed. Regular testing can help you maintain optimal levels. If you are concerned about your vitamin D, speak with your doctor.
Remember that everyone’s needs are different. Factors like age, skin tone, and lifestyle affect how much vitamin D you need. A personalized approach, with guidance from a healthcare professional, can help you achieve and maintain healthy vitamin D levels.
By understanding vitamin D and its sources, you can take steps to ensure you get enough of this essential nutrient. Your bones, immune system, and overall health will benefit.
Vitamin D is indeed fat-soluble, meaning it’s absorbed and transported in the body along with fats. It plays a critical role in numerous physiological processes, including calcium absorption and bone health.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
The body synthesizes Vitamin D3 when skin is exposed to ultraviolet B (UVB) radiation. It can also be obtained from dietary sources, such as fatty fish, and vitamin D supplements, which are available in both D2 and D3 forms.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
Vitamin D is essential for the intestinal absorption of calcium. Without sufficient vitamin D, the body cannot absorb calcium efficiently, impacting bone density and strength. This process is essential for preventing osteoporosis.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
Vitamin D receptors are present on immune cells, indicating a role in immune function. Also, studies have suggested a link between vitamin D deficiency and mood disorders, such as depression. The exact mechanisms for the mood aspect are still being researched.
Source: “Vitamins D2 and D3 Have Overlapping But Different Effects on the Human Immune System Revealed Through Analysis of the Blood Transcriptome” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8908317/
Vitamin D2 is primarily derived from plants and fungi through UV radiation, while Vitamin D3 is produced in the skin of animals including humans by UVB exposure or obtained from animal-based foods.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
Specifically, the UVB radiation converts 7-dehydrocholesterol in the skin to previtamin D3, which is then converted to vitamin D3. This process is one of the body’s main ways of getting Vitamin D.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
Melanin, a pigment in the skin, acts as a natural sunscreen and reduces UVB absorption. Individuals with darker skin have higher melanin levels, requiring longer sun exposure to produce the same amount of Vitamin D3 as those with lighter skin. Other factors, such as time of day, location, age, etc. also play a role.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
Many foods, like milk, cereals, and some plant-based alternatives, are fortified with vitamin D to increase intake. They provide an important source of this nutrient, especially for populations who have limited access to sunshine or who follow restrictive diets.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
Both D2 and D3 increase blood levels of Vitamin D, but research suggests that D3 is generally more effective at raising and maintaining vitamin D levels for a longer period due to how the body metabolizes each form. Some studies suggest D3 increases levels by 56–87% more than D2.
Source: “Differential Effects of Oral Boluses of Vitamin D2 vs Vitamin D3 on Vitamin D Metabolism: A Randomized Controlled Trial” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6797055/
Vitamin D supplements provide a reliable source of the vitamin, particularly for people who cannot get enough from sunlight or diet alone. This is especially useful for the elderly or those with medical conditions, who often cannot get enough Vitamin D in normal ways.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
The threshold of 20 ng/mL is commonly used to define vitamin D deficiency in clinical settings. It’s recognized as a widespread health concern, with an estimated billion people being affected, but the overall number can fluctuate depending on the study and criteria used.
Source: “Vitamin D supplementation for term breastfed infants to prevent vitamin D deficiency and improve bone health” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8812278/
Many vitamin D recommendations are based on the assumption of limited sun exposure. There is an ongoing debate in the scientific community about whether the current RDA is enough, and some experts argue that higher intakes are needed for optimal overall health.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
Vitamin D facilitates the absorption of calcium in the small intestine. When Vitamin D is insufficient, the body is less able to absorb calcium, leading to problems with bone density and potentially leading to conditions like osteoporosis.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
Several studies have indicated that vitamin D supplementation, especially in combination with calcium, can lower the risk of falls and fractures in older adults, though findings can vary based on dose, population, and other factors.
Source: “Impact of Vitamin D Status and Nutrition on the Occurrence of Long Bone Fractures Due to Falls in Elderly Subjects in the Vojvodina Region of Serbia” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11356805/
Some studies show a relationship between vitamin D levels and immune function, especially concerning respiratory infections, but the results can be inconsistent. The 2017 study cited may have had specific parameters and conditions, so the 12% figure is not a guarantee across all populations and circumstances. More research is needed to understand the nuances.
Source: “Vitamin D supplementation in a post-pandemic era: A narrative review” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10623655/
Research has shown an association between low vitamin D levels and depression. However, it’s not yet clear if low vitamin D directly causes depression, or if it’s a result of other factors. The exact mechanisms by which Vitamin D affects mood are still not fully understood, but there appears to be a clear correlation.
Source: “The Role of Water-Soluble Vitamins and Vitamin D in Prevention and Treatment of Depression and Seasonal Affective Disorder in Adults” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11206829/
The fact that vitamin D receptors (VDRs) are found in brain regions that play a role in mood and cognitive functions provides further evidence that vitamin D can directly impact these aspects of health. However, the specific mechanisms and overall effects are still under investigation.
Source: “The Effects of Vitamin D-Enriched Mushrooms and Vitamin D3 on Cognitive Performance and Mood in Healthy Elderly Adults: A Randomised, Double-Blinded, Placebo-Controlled Trial” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7766163/
Several studies have looked at the effect of vitamin D supplements on depression symptoms, but overall, the results have been varied, with some trials showing a positive effect and some showing no effect. Therefore, more research is needed to determine if vitamin D is an effective treatment for depression and what the best approach might be.
Source: “The Role of Water-Soluble Vitamins and Vitamin D in Prevention and Treatment of Depression and Seasonal Affective Disorder in Adults” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11206829/
The Recommended Dietary Allowance for vitamin D varies based on age, sex, and other life stages like pregnancy and breastfeeding. These recommendations are set by expert panels with the goal of meeting the nutrient needs of around 97-98% of the population to prevent deficiency.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
The scientific community continues to debate what constitutes optimal Vitamin D levels. Some researchers argue that higher levels are needed to maximize health outcomes, compared to what is currently recommended, but others suggest the data is not conclusive.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
The recommendation to maintain levels above 30 ng/mL stems from research associating better health outcomes with this level, rather than the cut-off of 20ng/mL for deficiency. This remains an area of active research and discussion within the medical field.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
The 25-hydroxyvitamin D (also known as 25(OH)D) test is the most accurate way to measure a person’s vitamin D levels, because it is the most abundant form of vitamin D in the blood, and is used as an indicator of overall levels.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
While the cutoff for deficiency is often cited as 20 ng/mL, some research suggests that levels above 30 ng/mL are associated with better health outcomes. However, this idea isn’t universally accepted and research continues.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
Regular testing can help individuals maintain ideal Vitamin D levels, but the frequency of testing should be individualized based on the person’s risk factors (e.g., limited sun exposure, older age, etc.) and their initial blood results. It’s best to discuss with a health professional to determine the correct testing schedule.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
Vitamin D toxicity is indeed not common but can occur due to excessive supplementation, as it is a fat-soluble vitamin. Toxicity is rarely achieved from diet or normal sun exposure alone, and usually occurs with extremely high doses of supplements.
Source: “Vitamin D Metabolites: Analytical Challenges and Clinical Relevance” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8892115/
The safe upper limit for vitamin D intake is set at 4,000 IU by many guidelines. However, in certain circumstances, medical professionals may suggest higher doses for specific conditions, but they should be taken with medical supervision to prevent the risk of toxicity.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
Vitamin D is essential during pregnancy for fetal skeletal development and to help ensure calcium absorption. Insufficient vitamin D levels during pregnancy have been linked to complications, but research on the link is ongoing.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
The RDA for vitamin D in pregnancy and breastfeeding is 600 IU per day, but higher doses may be recommended by healthcare professionals for those with known deficiencies or risk factors. This should be done with advice from a medical provider.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
Breast milk usually does not contain sufficient vitamin D for babies. Consequently, breastfed infants often require vitamin D supplementation from their first few days of life to prevent deficiency. This recommendation is commonly given by health professionals.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
Vitamin D plays a critical role in calcium absorption and bone mineralization, especially during growth and development. Insufficient vitamin D can lead to rickets, a condition characterized by soft, weak bones.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
Breastfed infants need vitamin D supplementation from birth, as breast milk does not provide enough. Formula-fed babies may not need supplements if they receive at least 32 ounces of vitamin D-fortified formula per day, but it should be confirmed with their doctor.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
The RDA for vitamin D for adults over 70 years of age is 800 IU daily. Due to reduced skin synthesis and potential absorption issues, some individuals may need higher doses to maintain optimal levels. This should be determined in consultation with their medical provider.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
Vitamin D is essential for bone health, and adequate intake can lower the risk of osteoporosis, falls, and fractures. This helps to maintain mobility, independence, and a good quality of life for older adults. It is very important for maintaining mobility.
Source: “Interventions for preventing falls in older people in care facilities and hospitals” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6148705/
Vitamin D can interact with many other nutrients in the body, which can affect its absorption and utilization. These interactions are complex, and it’s important to have a balanced nutrient intake overall.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
Vitamin D synthesis from sunlight varies depending on the intensity of UVB radiation, which varies by season. In areas far from the equator, levels tend to decrease during winter months due to less sunlight exposure.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
Summer sunlight allows for increased Vitamin D synthesis by the skin. During winter, shorter days and less exposure to the sun lead to a decrease in Vitamin D production. This is why those in areas far from the equator are at risk for deficiencies during the winter months.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
Because Vitamin D levels fluctuate seasonally due to changing sun exposure, attention to Vitamin D intake can help prevent deficiencies. This can include an increased intake of vitamin D-rich foods, supplements, and/or a focus on light exposure. People at risk of seasonal deficiencies are often advised to take a supplement, particularly during the winter months.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
Few foods naturally contain large amounts of Vitamin D, which makes it difficult to get enough from diet alone. Fatty fish, egg yolks, and fortified foods are the best dietary sources, and most people need a combination of sun exposure, diet, and sometimes supplements to meet their vitamin D needs. It’s extremely rare to get enough vitamin D from diet alone.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
The amount of sun exposure needed varies depending on many factors, such as skin tone, time of day, location, and more. Light-skinned individuals often need less time in the sun than those with darker skin to synthesize the same amount of Vitamin D. It’s always critical to take into consideration that excessive sun exposure can cause skin damage, and to practice sun safety.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
Vitamin D deficiency can lead to symptoms like fatigue, bone pain, and more frequent infections. Many people with low levels, however, do not exhibit any symptoms, so blood tests are the only way to definitively assess a person’s status.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
Vitamin D toxicity is possible from excessive intake of supplements. Symptoms can include nausea, vomiting, weakness, and kidney issues. While the safe upper limit for adults is generally 4,000 IU per day, a medical professional may prescribe higher doses under certain circumstances and with proper monitoring.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
Some research suggests a link between vitamin D deficiency and obesity. Correcting a deficiency may support weight loss efforts in certain individuals, but Vitamin D is not a standalone weight loss solution. Diet and exercise are the most effective strategies for weight management.
Source: “Vitamin D status is heritable and under environment‐dependent selection in the wild” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9545857/
Daily vitamin D supplements are often recommended for maintaining a steady level in the bloodstream. However, larger weekly or monthly doses may be effective in some individuals, especially those who have difficulty remembering to take supplements daily. It is important to consult with a healthcare provider to determine the best dosing schedule.
Source: “Vitamin D Metabolites: Analytical Challenges and Clinical Relevance” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8892115/
