There are many kinds of vitamin D, how should I choose?

When it comes to preventing osteoporosis, the first thing that comes to mind is often calcium supplementation, and vitamin D supplementation is often ignored, which is very important for promoting intestinal absorption of calcium. If vitamin D is deficient, calcium absorption will be greatly discounted. Clinically, vitamin D is often used in conjunction with calcium, if calcium is compared to the "hero in front of the stage" to promote bone growth and health, then vitamin D is the "behind-the-scenes hero" to help calcium achieve its purpose.

Source of vitamin D for the human body

The body's vitamin D is mainly converted from 7-dehydrocholesterol in the skin by ultraviolet radiation, and a small amount is obtained from some meat foods (such as animal liver, marine fish, egg yolk, lean meat, dairy products, cream, etc.). However, these ordinary vitamin D is not biologically active, must be activated by the liver and kidneys, first in the liver through the action of 25-hydroxylase, into a partially active 25-hydroxyvitamin D [25-(OH)D], and then transported to the kidneys, 25-(OH)D in the kidneys through the action of 1-α hydroxylase, again hydroxylated, the formation of 1,25-dihydroxyvitamin D [1,25 (OH)2D], into a strong physiological activity of vitamin D, that is, " Active Vitamin D".

How to determine if there is a vitamin D deficiency

Clinically, the nutritional status of vitamin D in the body is mainly determined based on the serum "25-hydroxyvitamin D" level, and the evaluation criteria are as follows:

Appropriate amounts of vitamin D supplementation for different populations

The 2013 edition of the "Reference Intake of Dietary Nutrients for Chinese Residents" recommends that the general population aged 0 to 64 years old need to supplement with vitamin D 400 IU per day; the general population over 65 years old, due to lack of sunshine or poor intake and absorption, need to supplement vitamin D 600 IU per day; pregnant and lactating women need to supplement vitamin D 1500 to 2000 IU per day; and the daily application dose of vitamin D in osteoporosis patients should reach 800 to 1200 IU.

Note: Vitamin D referred to here refers to regular vitamin D, not active vitamin D.

What vitamin D is commonly used in clinical practice? How to choose?

Vitamin D commonly used in clinical practice can be roughly divided into two categories: ordinary vitamin D (including its compound preparations) and active vitamin D.

"Common vitamin D" has a high safety profile, a wide range of doses, rarely leads to poisoning due to excessive intake, and is mainly used clinically as a nutrient to correct vitamin D deficiency and prevent rickets in children and osteoporosis in the elderly. The risk of hypercalcemia caused by active vitamin D is significantly higher than that of ordinary vitamin D, the use of a narrow dose range, overdose can lead to vitamin D poisoning, clinically mainly as a drug, for the treatment of osteoporosis.

They are introduced as follows:

1. Ordinary vitamin D and its compound preparations

Representative drugs: vitamin D3 drops (400 IU / capsule), vitamin AD softgels (each capsule contains vitamin A 1000 IU, vitamin D3 1000 IU), calci D3 tablets (each tablet contains calcium 600mg, contains vitamin D3 125IU), cod liver oil, alendronate sodium vitamin D3 tablets (formega) and so on.

Suitable for: pregnant and lactating women, infants and young children, insufficient sunlight exposure, the elderly and other high-risk groups of vitamin D deficiency, mainly used for the prevention of rickets in children and elderly osteoporosis.

Note: It is not clinically recommended to correct vitamin D deficiency with active vitamin D.

2. Active vitamin D

Representative drugs: alphacalciferol (1α-hydroxyvitamin D), calciene glycol (25-hydroxyvitamin D) and calcitriol (1,25 dihydroxyvitamin D), the first two are only once hydroxylated, belonging to the semi-active vitamin D, while "calcitriol" after liver and kidney two hydroxylation, belongs to the fully active vitamin D, is the most active vitamin D.

Suitable for the population: Active vitamin D is mainly used for the clinical treatment of osteoporosis, suitable for all kinds of osteoporosis patients.

1) Alphacalcidol

No kidney activation is required, but it needs to be activated by the liver to have biological activity, which is suitable for patients with renal insufficiency but normal liver function, especially patients with renal bone disease and the elderly.

2) Calcined glycol

Liver metabolism activation is not required, but renal 1α hydroxylase activation is required. Suitable for patients with abnormal liver function but normal renal function.

3) Calcitriol

It is completely biologically active and can be effective without liver and kidney transformation, so it is suitable for the treatment of various types of osteoporosis, especially in patients with osteoporosis with hepatic and renal insufficiency.

summary

In short, the physiological activity, safety, dosage range, and indications of ordinary vitamin D and active vitamin D are not the same, and cannot be regarded as equivalent and replace each other, in addition, active vitamin D also has semi-active and fully active points, and the indications are also different, and clinical attention should be paid to reasonable selection.