Vitamin D: The Complete Guide

• Ultraviolet B (UVB) rays from sunlight convert 7-dehydrocholesterol in the skin to previtamin D3.
• Previtamin D3 in the skin (or vitamin D3 from diet or supplements) is transported to the liver.

• In the liver, previtamin D3 is converted into calcidiol (25-hydroxyvitamin D), the storage form of vitamin D.
• Calcidiol is sent to the kidneys where it is transformed into calcitriol (1,25-dihydroxy vitamin D), the biologically active form.
• Calcitriol stimulates the absorption of dietary calcium in the intestines, crucial for bone health, and aids in muscle development. It also helps regulate immune system functions.

• Any excess vitamin D is metabolized in the liver.
• The inactive forms of metabolized vitamin D are excreted into the intestines through bile.
• Inactive vitamin D metabolites are primarily expelled through feces, with minimal amounts eliminated via urine.

• Cod Liver Oil: 34.0 mcg per 1 tablespoon
• Salmon (sockeye): 14.2 mcg per 3 ounces
• Trout (rainbow, farmed, cooked): 16.2 mcg per 3 ounces
• Sardines (Atlantic, canned in oil, drained): 1.2 mcg for 2 sardines
• Tuna fish (light, canned in water, drained): 1.0 mcg per 3 ounces

• Beef Liver (braised): 1.0 mcg per 3 ounces
• Chicken Breast (roasted): 0.1 mcg per 3 ounces
• Egg (scrambled, large): 1.1 mcg per egg
• Milk (2% milkfat, vitamin D fortified): 2.9 mcg per cup
• Cheese (cheddar): 0.4 mcg per 1.5 ounces

• Mushrooms (white, raw, sliced, exposed to UV light): 9.2 mcg per 1/2 cup
• Mushrooms (portabella, raw, diced): 0.1 mcg per 1/2 cup

• Lentils (boiled): 0 mcg per 1/2 cup
• Edamame (shelled, cooked): 0 mcg per 1/2 cup
• Almonds (dry roasted): 0 mcg per 1 ounce
• Sunflower Seeds (roasted): 0 mcg per 1/2 cup

• Rice (brown, long-grain, cooked): 0 mcg per 1 cup
• Whole Wheat Bread (1 slice): 0 mcg per slice
• Ready-to-eat Cereal (fortified with 10% of the DV for vitamin D): 2.0 mcg per serving

Capsules are a convenient and easy-to-swallow delivery method for supplements that provide a pre-measured dose. They are particularly beneficial for individuals who may not enjoy the taste of the supplement in its natural form or when taken as a powder or liquid. Capsules are also portable and discreet, making them easy to take while traveling or on the go.

One of the main advantages of capsules is that they eliminate the need for measuring doses, which can be time-consuming and may lead to inconsistencies in dosage. The pre-measured nature of capsules ensures that the individual takes the same amount each time, making it easier to monitor and maintain a consistent supplementation routine.

Tablets are a convenient and easy-to-swallow form of supplement that offers a pre-measured dose. They eliminate the need for measuring, making them ideal for those who find measuring doses inconvenient. Tablets are also portable and discreet, allowing for easy consumption on the go.

One of the main benefits of tablets is their ease of use. They can be quickly swallowed with water, making them a simple and efficient way to incorporate supplements into a daily routine.

Soft gels are a type of capsule that contains a liquid form of the vitamin or supplement. They are easy to swallow and provide a pre-measured dose. Soft gels are known for their fast absorption rate, as the liquid content is quickly released and absorbed by the body.

This delivery method is particularly beneficial for individuals who have difficulty absorbing nutrients from traditional pills. Soft gels are also easy to digest and gentle on the stomach, making them a good choice for those with sensitive digestive systems. However, it's important to store soft gels properly, as they are more susceptible to degradation from heat and light compared to other delivery methods.

Chewable supplements are a convenient and enjoyable delivery method, particularly for those who have difficulty swallowing pills. They come in various flavors, making them more palatable and easier to consume. Chewables are often formulated to provide a pre-measured dose, ensuring consistent intake.

Chewable supplements are a good option for children or adults who prefer a tasty alternative to traditional pills. However, some chewable supplements may contain added sugars or artificial flavors, so it's essential to read the ingredient list carefully and choose a reputable brand.

Powdered vitamins and supplements offer versatility in consumption. They can be easily mixed into various beverages or foods, such as smoothies, juices, or yogurt, allowing for customization based on individual taste preferences. Powders also allow for flexible dosing, enabling individuals to adjust the amount consumed according to their needs or as directed by a healthcare professional.

However, measuring the correct dose of powdered supplements requires the use of a scoop or scale, which may be less convenient compared to pre-measured options like tablets or capsules.

Liquid extracts are a concentrated form of a supplement that offer fast absorption and flexible dosing. The liquid form allows for quick absorption into the bloodstream, potentially leading to faster effects compared to capsules or tablets. The dropper enables precise dosage adjustments, making it easier to tailor the amount consumed to individual needs or as directed by a healthcare professional.

Liquid extracts may also provide enhanced bioavailability, as some may contain additional compounds or solvents that improve the absorption and utilization of the active ingredients in the body. However, they may have a strong taste that some individuals find unpleasant, and they require careful attention to dosage to avoid consuming too much of the supplement.

Proper storage is essential to maintain the quality and potency of liquid extracts, as exposure to light, heat, or air can degrade the active ingredients over time.

• People with Limited Sun Exposure: People with restricted access to sunlight, such as those living in northern latitudes or working indoors, may benefit from vitamin D supplementation.
• Dark-Skinned People: People with darker skin tones may have reduced vitamin D synthesis from sunlight and could consider supplementation.
• Older People: Aging people may experience a decline in your skin's ability to produce vitamin D, making supplementation relevant.
• Vegetarians and Vegans: Those following plant-based diets might choose vitamin D2 supplements, as they lack animal-derived sources.
• Infants and Children: Vitamin D supplements are often recommended for infants, especially those who are exclusively breastfed, and children to support healthy growth.
• People with Malabsorption Issues: People with conditions affecting nutrient absorption may consider vitamin D supplements, but consultation with a healthcare professional is essential.

• People with Hypercalcemia Risk: People at risk of hypercalcemia should be cautious, as excessive vitamin D may lead to elevated calcium levels.
• Those on Certain Medications: People taking medications that interact with vitamin D metabolism should consult with a healthcare provider.
• People with Kidney Issues: People with kidney problems should be cautious, as impaired kidney function may affect vitamin D metabolism.
• Pregnant or Breastfeeding Women: Pregnant or breastfeeding women should seek guidance from healthcare professionals before supplementing.
• People with Known Allergies: People with known allergies to vitamin D or its components should avoid supplementation.
• Those without Deficiency Risk Factors: People without risk factors for vitamin D deficiency may not require supplements; a balanced diet and sunlight exposure may suffice.