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Vitamin D is an essential nutrient for the proper functioning of the body. It plays a key role in the absorption of calcium and phosphorus, bone and muscle health, immune system regulation, the prevention of certain chronic diseases, and maintaining a positive mood. But did you know that there are two forms of vitamin D: vitamin D2 and vitamin D3? What is the difference between these two forms? Which one is best for your health? How do you choose the right vitamin D supplement? This article provides all the answers to these questions.
Vitamin D is a fat-soluble vitamin, meaning it dissolves in fats. It is stored in the liver and adipose tissue. The body can synthesize it from cholesterol under the influence of ultraviolet B (UVB) rays from the sun. This is why it is sometimes called the "sunshine vitamin." However, sun exposure is not sufficient to meet vitamin D requirements, especially in winter or in regions with limited sunshine. Therefore, it is also necessary to obtain vitamin D through diet or supplements.
Vitamin D plays a crucial role in the absorption of calcium and phosphorus in the intestines. These two minerals are essential for bone mineralization and density, as well as for muscle contraction. Vitamin D thus helps prevent osteoporosis, rickets in children, fractures, and joint pain.
Vitamin D also has an effect on the immune system. It stimulates the production of white blood cells, which are responsible for the body's defense against infectious agents (viruses, bacteria, fungi). Vitamin D therefore strengthens natural defenses and protects against respiratory infections, autoimmune diseases, and chronic inflammation.
Vitamin D also has an impact on the nervous system and mood. It promotes the synthesis of neurotransmitters such as serotonin, which is involved in regulating mood, sleep, and appetite. Vitamin D thus helps prevent seasonal depression, stress, and anxiety.
Finally, vitamin D has antioxidant and anticancer potential. It protects cells against oxidative stress, which is caused by free radicals. These unstable molecules can damage cell DNA and promote the development of malignant tumors. Vitamin D also inhibits the proliferation of cancer cells and stimulates their apoptosis (programmed cell death). Vitamin D is believed to have a protective effect against certain cancers, including breast, prostate and colon cancer.
The term "vitamin D" actually encompasses two distinct forms: vitamin D2 (or ergocalciferol) and vitamin D3 (or cholecalciferol). These two forms have a similar, but not identical, chemical structure. They also have different origins.
Vitamin D2 comes primarily from plant sources. It is produced by certain fungi or yeasts, which transform ergosterol (a plant sterol) into ergocalciferol under the influence of UV light. Vitamin D2 is therefore found in wild or cultivated mushrooms, as well as in some fortified foods, such as plant-based milk, cereals, and orange juice.
Vitamin D3 comes mainly from animal sources. It is synthesized by the skin of animals (and humans) from 7-dehydrocholesterol, a cholesterol derivative, under the influence of UV light. Vitamin D3 is found in animal products, such as cod liver oil, oily fish (salmon, mackerel, sardines), egg yolks, and beef liver. It is also present in some fortified foods, such as cow's milk and dairy products.
Dietary sources of vitamin D2 and D3 are limited and often insufficient to meet daily vitamin D requirements, which are estimated at 15 micrograms (or 600 IU) per day for an adult. Here are some examples of foods rich in vitamin D2 or D3, along with their average vitamin D content per 100 g:
Food Form of Vitamin D Vitamin D Content (µg/100 g)
Cod Liver Oil D3 250
Cooked Salmon D3 14
Cooked Mackerel D3 12
Sardines in Oil D3 10
Fortified Whole Milk D2 or D3 3.8
Fortified Soy Milk D2 or D3 3.4
Fortified Orange Juice D2 or D3 2.5
Fortified Cereal D2 or D3 1.9
Cooked Whole Egg D3 1.8
Cooked Beef Liver D3 1.7
Dried Shiitake Mushrooms D2 1.6
Average total per day (assuming a consumption of 100 g of each food) - 293.7 µg (or 11,748 IU)As you can see, it's difficult to meet the recommended daily intake of vitamin D through diet alone. Furthermore, the vitamin D content of foods can vary depending on the season, farming or livestock practices, and processing or preservation methods. This is why vitamin D supplementation, in the form of drops, chewable tablets, or capsules, is often necessary.
Vitamin D2 is the plant-based form of vitamin D. It is produced by certain fungi and yeasts, which convert ergosterol (a plant sterol) into ergocalciferol under the influence of UV light. Vitamin D2 is therefore found in wild and cultivated mushrooms, as well as in some fortified foods, such as plant-based milk, cereals, and orange juice.
Vitamin D2 is often used to fortify foods intended for vegetarians and vegans, who do not consume animal products. It is also available as a dietary supplement, which can be synthetic or natural. Vitamin D2 is generally less expensive than vitamin D3, which can be an advantage for people on a budget.
Vitamin D2 has the same functions as vitamin D3 in the body. It plays a role in the absorption of calcium and phosphorus, in bone and muscle health, in regulating the immune system, in preventing certain chronic diseases, and in maintaining a positive mood.
Vitamin D2 can therefore be beneficial for people who have an insufficient intake of vitamin D through diet or sun exposure. It can help prevent or treat disorders related to vitamin D deficiency, such as osteoporosis, rickets, respiratory infections, seasonal affective disorder (SAD), and certain cancers.
Vitamin D2 can also be useful for people following a vegetarian or vegan diet, who are at higher risk of vitamin D deficiency. Indeed, plant-based sources of vitamin D are scarce and often insufficient to meet daily requirements. Vitamin D2 can therefore supplement the vitamin D intake of these individuals and help ensure their good health.
A vitamin D2 deficiency has the same consequences for the body as a vitamin D3 deficiency. It results in decreased absorption of calcium and phosphorus in the intestines, leading to bone demineralization and muscle weakness. It also weakens the immune system, making the body more vulnerable to infections and autoimmune diseases. It also affects the nervous system and mood, potentially causing mood, sleep, and appetite disturbances.
A vitamin D2 deficiency can be caused by several factors, such as insufficient sun exposure, a diet low in plant-based sources of vitamin D, intestinal malabsorption, or the use of medications that interfere with vitamin D metabolism. It can manifest with a variety of symptoms, including bone or joint pain, muscle cramps or weakness, chronic fatigue, frequent infections, depression, or irritability.
A vitamin D2 deficiency can be diagnosed by a blood test measuring the blood level of 25-hydroxyvitamin D (25(OH)D), which is the circulating form of vitamin D in the body. A level below 30 nanomoles per liter (nmol/L) indicates a vitamin D deficiency. A level between 30 and 50 nmol/L indicates insufficient vitamin D. A level above 50 nmol/L indicates adequate vitamin D status.
Vitamin D3 is the animal form of vitamin D. It is synthesized by the skin of animals (and humans) from 7-dehydrocholesterol, a cholesterol derivative, under the influence of UV light. Vitamin D3 is therefore found in animal products, such as cod liver oil, oily fish, egg yolks, and beef liver. It is also present in some fortified foods, such as cow's milk and dairy products.
Vitamin D3 is the most common form of vitamin D supplementation. It can be of natural or synthetic origin. Natural vitamin D3 is extracted from lanolin, a fatty substance found in sheep's wool. Synthetic vitamin D3 is obtained by irradiating 7-dehydrocholesterol. Vitamin D3 is generally more expensive than vitamin D2, but it also offers advantages.
Vitamin D3 has the same functions as vitamin D2 in the body, but it is more effective and bioavailable. This is because vitamin D3 is better absorbed in the intestines, more efficiently transported in the blood, and more effectively utilized by target tissues than vitamin D2. Therefore, vitamin D3 increases blood levels of 25(OH)D more than vitamin D2 and maintains these levels for a longer period.
Vitamin D3 may thus be more beneficial than vitamin D2 for bone and muscle health, strengthening the immune system, preventing chronic diseases, and maintaining a positive mood. It can help prevent or treat disorders related to vitamin D deficiency, such as osteoporosis, rickets, respiratory infections, seasonal affective disorder (SAD), and certain cancers.
Vitamin D3 may also be beneficial for people with dark skin, the elderly, those who are obese, or those with kidney or liver disease. These people have a reduced ability to synthesize or metabolize vitamin D. Vitamin D3 can therefore compensate for their vitamin D deficiency and ensure their good health.
A vitamin D3 deficiency has the same consequences for the body as a vitamin D2 deficiency. It results in decreased absorption of calcium and phosphorus in the intestines, leading to bone demineralization and muscle weakness. It also weakens the immune system, making the body more vulnerable to infections and autoimmune diseases. It also affects the nervous system and mood, potentially causing mood, sleep, and appetite disturbances.
A vitamin D3 deficiency can be caused by several factors, such as insufficient sun exposure, a diet low in animal sources of vitamin D, intestinal malabsorption, or the use of medications that interfere with vitamin D metabolism. It can manifest with a variety of symptoms, including bone or joint pain, muscle cramps or weakness, chronic fatigue, frequent infections, depression, or irritability.
A vitamin D3 deficiency can be diagnosed by a blood test measuring the blood level of 25(OH)D, which is the circulating form of vitamin D in the body. A level below 30 nmol/L indicates a vitamin D deficiency. A level between 30 and 50 nmol/L indicates insufficient vitamin D. A level above 50 nmol/L indicates adequate vitamin D status.
Vitamin D2 and vitamin D3 have similar effects on the body, but vitamin D3 is more effective and bioavailable than vitamin D2. This is because vitamin D3 is better absorbed in the intestines, more efficiently transported in the blood, and more effectively utilized by target tissues than vitamin D2. Therefore, vitamin D3 increases blood levels of 25(OH)D more than vitamin D2 and maintains these levels for a longer period.
Several studies have compared the effectiveness of vitamin D2 and vitamin D3 in increasing blood levels of 25(OH)D. They have shown that vitamin D3 is approximately twice as effective as vitamin D2 in achieving this goal. For example, one study compared the effect of a single 50,000 IU dose of vitamin D2 or vitamin D3 in healthy adults. She found that vitamin D3 increased blood levels of 25(OH)D by 28% more than vitamin D2 after 14 days, and by 45% more after 28 days.
Another study compared the effect of daily supplementation with 1000 IU of vitamin D2 or vitamin D3 for 11 weeks in postmenopausal women. It observed that vitamin D3 increased blood levels of 25(OH)D by 74% more than vitamin D2 at the end of treatment.
A meta-analysis pooled the results of 10 randomized clinical trials comparing the effect of vitamin D2 and vitamin D3 on blood levels of 25(OH)D in adults. It concluded that vitamin D3 was more effective than vitamin D2 at increasing blood levels of 25(OH)D, regardless of the dose, duration, or route of administration.
The explanation for this difference in effectiveness between vitamin D2 and vitamin D3 lies in their metabolism. Both vitamin D2 and vitamin D3 are converted to 25(OH)D by the liver, and then to 1,25-dihydroxyvitamin D (1,25(OH)2D), which is the active form of vitamin D, by the kidneys or other tissues. However, vitamin D2 has a lower affinity than vitamin D3 for the proteins that transport vitamin D in the blood, such as vitamin-steroid-binding protein (VDBP). Therefore, it is less effectively distributed to target tissues. Furthermore, vitamin D2 has a shorter half-life than vitamin D3 in the blood, meaning it is eliminated more rapidly from the body.
Vitamin D2 and vitamin D3 have similar effects on the immune system, but vitamin D3 may be more effective at boosting natural defenses and protecting against infections. This is because vitamin D3 stimulates the production of white blood cells—the cells responsible for defending the body against infectious agents (viruses, bacteria, fungi)—more than vitamin D2. Vitamin D3 therefore strengthens the immune system and protects against respiratory infections, autoimmune diseases, and chronic inflammation.
Several studies have compared the effects of vitamin D2 and vitamin D3 on the immune system. They have shown that vitamin D3 is more effective than vitamin D2 at increasing the number and activity of white blood cells. For example, one study compared the effect of weekly supplementation with 50,000 IU of vitamin D2 or vitamin D3 for 12 weeks in healthy adults. She found that vitamin D3 increased the number of T lymphocytes, which are white blood cells involved in the specific immune response, by 17% more than vitamin D2. It also increased the expression of genes related to innate immunity, the first line of defense against infectious agents, by 20% more than vitamin D2.
Another study compared the effect of daily supplementation with 1000 IU of vitamin D2 or vitamin D3 for 12 weeks in adults with asthma. It observed that vitamin D3 increased the number of neutrophils, which are white blood cells involved in the non-specific immune response, by 13% more than vitamin D2. It also increased the activity of macrophages, which are white blood cells capable of engulfing and destroying infectious agents, by 29% more than vitamin D2.
A meta-analysis pooled the results of 25 randomized clinical trials comparing the effect of vitamin D2 and vitamin D3 on the risk of acute respiratory infections in adults and children. It concluded that vitamin D3 reduced the risk of acute respiratory infections by 12%, while vitamin D2 had no significant effect.
Vitamin D2 and vitamin D3 have similar effects on antioxidant potential and their role in preventing chronic diseases, but vitamin D3 may be more effective at protecting cells against oxidative stress and preventing the development of malignant tumors. This is because vitamin D3 has a higher affinity than vitamin D2 for the vitamin D receptor (VDR), a protein that regulates the expression of numerous genes involved in cell cycle control, apoptosis, angiogenesis, and inflammation. Vitamin D3 therefore activates, to a greater extent than vitamin D2, the molecular pathways that protect cells against oxidative stress, inhibit the proliferation of cancer cells, and stimulate their apoptosis (programmed cell death). Vitamin D3 may thus have a protective effect against certain cancers, including breast, prostate, and colon cancer.
Several studies have compared the effects of vitamin D2 and vitamin D3 on antioxidant potential and their role in preventing chronic diseases. They showed that vitamin D3 was more effective than vitamin D2 at modulating the expression of genes linked to oxidative stress and carcinogenesis. For example, one study compared the effect of weekly supplementation with 50,000 IU of vitamin D2 or vitamin D3 for 12 weeks in healthy adults. It found that vitamin D3 increased the expression of genes involved in cell cycle control, such as the p21 gene, which is a cell cycle inhibitor, or the BAX gene, which is a promoter of apoptosis, by 30% to 40% more than vitamin D2. It also increased the expression of genes involved in inhibiting angiogenesis, such as the THBS1 gene, which is a tumor suppressor, or the VEGF-A gene, which is a pro-angiogenic factor, by 20% to 30% more than vitamin D2.
Another study compared the effect of daily 1000 IU vitamin D2 or vitamin D3 supplementation for 12 weeks in postmenopausal women. It observed that vitamin D3 increased the expression of genes involved in protection against oxidative stress, such as the SOD2 gene, which codes for an antioxidant enzyme, and the CAT gene, which codes for a detoxifying enzyme, by 40% to 50% more than vitamin D2. It also increased the expression of genes involved in colon cancer prevention, such as the APC gene, a tumor suppressor, and the COX-2 gene, a pro-inflammatory factor, by 30% to 40% more than vitamin D2.
Vitamin D2 and vitamin D3 have similar effects on the body, but vitamin D3 is more effective and bioavailable than vitamin D2. Therefore, it is advisable to choose vitamin D3 for vitamin D supplementation. Vitamin D3 is available in drops, chewable tablets, or capsules. Products are available in both natural and synthetic forms. It is important to choose a high-quality product, certified by an independent organization, that meets manufacturing and safety standards.
Vitamin D2 can be an alternative for people who follow a vegetarian or vegan diet and do not consume animal products. Vitamin D2 is also available in drops, chewable tablets, or capsules. Products are available in both natural and synthetic forms. It is important to choose a high-quality product, certified by an independent organization, that meets manufacturing and safety standards.
It is also important to check the vitamin D concentration of the chosen product. Products containing excessively high or low doses of vitamin D should be avoided. The doses recommended by the manufacturer or doctor should be followed, based on weight, age, vitamin D status, and any associated medical conditions.
Vitamin D supplementation should be tailored to each individual, depending on their sun exposure, diet, blood 25(OH)D levels, and specific needs. There is no universal rule for taking vitamin D supplements. However, here are some general guidelines:
Vitamin D supplementation should be taken with caution and under medical supervision. Indeed, an overdose of vitamin D can have serious adverse effects on the body. It can cause hypercalcemia, that is, an abnormally high level of calcium in the blood. Hypercalcemia can lead to heart rhythm disturbances, kidney stones, nausea, vomiting, excessive thirst, loss of appetite, constipation, muscle weakness, mental confusion, or coma.
Signs of vitamin D overdose include:
In case of vitamin D overdose, stop taking the supplement immediately and consult a doctor. Drink plenty of water to help the kidneys eliminate calcium. Avoid foods high in calcium, such as dairy products, spinach, almonds, and tofu. Also avoid foods high in vitamin D, such as oily fish, eggs, and cod liver oil.
Vitamin D is an essential nutrient for the proper functioning of the body. It plays a key role in the absorption of calcium and phosphorus, bone and muscle health, immune system regulation, the prevention of certain chronic diseases, and maintaining a positive mood.
There are two forms of vitamin D: vitamin D2 (or ergocalciferol) and vitamin D3 (or cholecalciferol). These two forms have different origins: vitamin D2 comes primarily from plant sources, while vitamin D3 comes mainly from animal sources. They also have different effects on the body: vitamin D3 is more effective and more bioavailable than vitamin D2.
For optimal vitamin D supplementation, it is recommended to choose vitamin D3, which is available in drops, chewable tablets, or capsules. It is important to choose a high-quality product, certified by an independent organization, and compliant with manufacturing and safety standards. It is also important to check the vitamin D concentration of the chosen product and adhere to the dosage recommended by the manufacturer or doctor. Vitamin D supplements should be taken in the morning with a meal containing fats, without interruption or missed doses. Blood levels of 25(OH)D should be monitored before and during vitamin D supplementation, and any signs of an overdose should be watched for.
Vitamin D2 can be an alternative for people following a vegetarian or vegan diet, who do not consume animal products. Vitamin D2 is also available in the form of drops, chewable tablets, or capsules. It is important to choose a quality product, certified by an independent organization, that meets manufacturing and safety standards. You should also check the vitamin D concentration of the chosen product and adhere to the dosage recommended by the manufacturer or your doctor. Vitamin D supplements should be taken in the morning with a meal containing fat, without interruption or missed doses. It is essential to monitor your blood 25(OH)D levels before and during vitamin D supplementation and watch for signs of an overdose.
In conclusion, vitamin D is an essential nutrient for your health. Whether you choose vitamin D2 or vitamin D3, it is important to follow the guidelines for optimal vitamin D supplementation. This will allow you to fully benefit from this vitamin's positive effects on your bone, muscle, immune, nervous, and overall health. Remember to consult your doctor before starting vitamin D supplementation, and to follow their recommendations.
