How to increase absorption of vitamin d
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Strategies to Increase Vitamin D Absorption
Vitamin D is essential for bone health and overall well-being, but many individuals struggle with achieving adequate levels despite supplementation. Research has identified several strategies to enhance the absorption of vitamin D, which can be crucial for those with deficiencies or absorption issues.
Dietary Fat and Vitamin D Absorption
Fat-Containing Meals
One of the most effective ways to increase vitamin D absorption is to consume it with a meal that contains fat. A study demonstrated that the absorption of vitamin D-3 was significantly higher when taken with a fat-containing meal compared to a fat-free meal. Specifically, the mean peak plasma vitamin D-3 level was 32% greater in subjects consuming fat-containing meals1. This suggests that incorporating dietary fat can enhance the bioavailability of vitamin D supplements.
Types of Fat: MUFA vs. PUFA
While the presence of fat in a meal is beneficial, the type of fat—whether monounsaturated (MUFA) or polyunsaturated (PUFA)—does not significantly impact vitamin D absorption. Research found no significant difference in vitamin D absorption between meals with high MUFA and high PUFA ratios1. Therefore, any dietary fat can be effective in improving vitamin D absorption.
Timing of Supplementation
Largest Meal of the Day
Taking vitamin D supplements with the largest meal of the day can also improve absorption. A study involving patients with vitamin D deficiency who were not responding to treatment found that taking vitamin D with their largest meal increased serum 25-hydroxyvitamin D levels by an average of 56.7%2. This approach leverages the higher fat content typically present in larger meals to enhance vitamin D absorption.
Mechanisms of Absorption
Passive Diffusion and Membrane Carriers
Vitamin D absorption is not solely dependent on passive diffusion; it also involves membrane carriers, particularly cholesterol transporters. Studies indicate that factors affecting cholesterol absorption can similarly influence vitamin D absorption3. This dual mechanism underscores the complexity of vitamin D absorption and the potential for dietary and physiological factors to impact its efficacy.
Calcium and Vitamin D
Calcium Absorption
While vitamin D is often recommended to enhance calcium absorption, the relationship is not straightforward. Research shows that increasing doses of vitamin D do not necessarily lead to a proportional increase in calcium absorption. For instance, a study found no significant increase in calcium absorption with higher doses of vitamin D in postmenopausal women4. Similarly, another study concluded that vitamin D supplementation did not significantly affect calcium absorption in young women7. These findings suggest that while vitamin D is crucial for bone health, its role in calcium absorption may be limited and influenced by other factors.
Conclusion
To maximize vitamin D absorption, it is beneficial to take supplements with a fat-containing meal, ideally the largest meal of the day. The type of fat in the meal does not significantly impact absorption, making it easier to incorporate this strategy into various dietary preferences. Understanding the mechanisms of vitamin D absorption and its interaction with calcium can further inform effective supplementation practices. By adopting these strategies, individuals can improve their vitamin D levels and overall health outcomes.
Sources and full results
Most relevant research papers on this topic
Dietary fat increases vitamin D-3 absorption.
Vitamin D-3 supplementation is more effectively absorbed when taken with a meal containing fat, but the ratio of monounsaturated to polyunsaturated fatty acids in the fat does not influence its absorption.
RCT
Highly CitedTaking vitamin D with the largest meal improves absorption and results in higher serum levels of 25‐hydroxyvitamin D
Taking vitamin D supplements with the largest meal of the day improves absorption and increases serum levels of 25-hydroxyvitamin D in patients with vitamin D deficiency.
Observational Study
Rigorous JournalIntestinal absorption of vitamin D: a systematic review
Vitamin D absorption involves passive diffusion and membrane carriers, with some data suggesting that fat consumption with vitamin D improves absorption.
Systematic ReviewHighly CitedVitamin D supplementation increases calcium absorption without a threshold effect.
Vitamin D supplementation increases calcium absorption without a threshold effect, making it unsuitable for determining vitamin D nutritional recommendations.
RCT
Very Rigorous JournalHighly CitedThe effect of vitamin D on calcium absorption in older women.
High doses of vitamin D3 do not significantly increase calcium absorption in postmenopausal women, and the same amount could be obtained from half a glass of milk or 100 mg elemental calcium.
RCTSupplementation with 1000 IU vitamin D/d leads to parathyroid hormone suppression, but not increased fractional calcium absorption, in 4-8-y-old children: a double-blind randomized controlled trial.
Vitamin D3 supplementation at 1000 IU/d increases 25(OH)D and decreases parathyroid hormone in children with average vitamin D intake below dietary recommendations, but does not significantly affect calcium absorption.
RCTVery Rigorous JournalVitamin D Does Not Increase Calcium Absorption in Young Women: A Randomized Clinical Trial
Vitamin D does not increase calcium absorption in young women with vitamin D insufficiency, suggesting no need to recommend it for this purpose in normal subjects.
RCTRigorous JournalVitamin D supplementation and calcium absorption during caloric restriction: a randomized double-blind trial.
Vitamin D supplementation increases calcium absorption and maintains calcium balance during weight loss, suggesting it is sufficient for maintaining calcium balance when calcium intake is 1.2 g/d.
RCTVery Rigorous JournalVitamin D and aging.
Increasing vitamin D intake to 800 IU daily and calcium intake to 1000 mg daily can reduce fractures in institutionalized individuals by 30%.
Highly CitedVitamin D supplementation guidelines
Higher vitamin D levels are associated with improved outcomes for various chronic diseases, and supplementation is recommended based on individual factors like age, body weight, and latitude.
Highly Cited