More than 1 billion people in the world lack this vitamin! If this physical examination index is lower than 30, be careful!

When 26-year-old Xiao Zhang (pseudonym) got his physical examination report, he found that his 25-hydroxyvitamin D level was only 8.9 ng/mL, far below the normal value (>30ng/mL). He quickly took the physical examination report to the report consultation room and asked, "Doctor, is this serious? Should I take vitamin D?"

The general practitioner told him: "Don't worry, here's what you need to know about vitamin D..."

01

Vitamin D deficiency criteria

The detection of 25-hydroxyvitamin D levels has been recognized as the most reasonable indicator to reflect vitamin D status.

02

Screening for vitamin D deficiency

Vitamin D deficiency is related to environmental and genetic factors. Common influencing factors include: age, skin color, season, geographical latitude, altitude, dressing habits, sunshine time, sun protection measures, eating habits, air pollution, obesity, and drugs that affect vitamin D metabolism.

Globally, more than 1 billion people have serum 25-hydroxyvitamin D levels that do not meet the recommended levels for maintaining bone and muscle health.

The following are people at high risk of vitamin D deficiency who are recommended to screen their blood 25-hydroxyvitamin D levels:

1. Special Populations

Pregnant and lactating women, elderly people with a history of falls and/or non-traumatic fractures, people who lack sunlight (working indoors, working at night, etc.), obese children and adults (BMI ≥ 30 kg/㎡), and people undergoing weight loss surgery.

Copyright image, no permission to reprint

2. Disease status

Rickets, osteomalacia, osteoporosis, hyperparathyroidism, chronic kidney disease, liver failure, intestinal malabsorption syndrome (acute and chronic diarrhea, steatorrhea, pancreatic cystic fibrosis, inflammatory bowel disease, radiation enteritis), lymphoma, granuloma-forming diseases (sarcoidosis, tuberculosis, AIDS, histoplasmosis, coccidioidomycosis, etc.).

3. Certain medications

Anti-epileptic drugs (phenytoin sodium, phenobarbital, etc.), glucocorticoids (prednisone, etc.), anti-tuberculosis drugs (rifampicin, etc.), azole antifungal drugs (ketoconazole, etc.), certain lipid-lowering drugs (cholestyramine, etc.).

03

What are the dangers of vitamin D deficiency?

1. Bone and muscle strength

For infants and children, vitamin D deficiency, abnormal vitamin D metabolism and abnormal action are important causes of rickets and osteomalacia.

Several studies have shown that vitamin D deficiency is associated with increased parathyroid hormone levels, increased bone resorption, bone loss, and increased risk of falls and fractures in middle-aged and elderly people. People with severe vitamin D deficiency have decreased muscle strength and an increased risk of falls.

2. Type 2 diabetes

Vitamin D deficiency is associated with an increased incidence of type 2 diabetes and is a potential risk factor for type 2 diabetes. Vitamin D may affect glucose metabolism by affecting pancreatic β-cell function, improving insulin sensitivity and glucose transport, and inducing increased conversion of proinsulin to insulin.

Copyright image, no permission to reprint

3. Cardiovascular disease

Low vitamin D levels are associated with atherosclerosis, coronary artery disease, myocardial infarction, heart failure, stroke, cardiovascular mortality and all-cause mortality. Vitamin D may participate in cardiovascular protection by affecting or regulating inflammatory cytokines, vascular calcification, and the renin-angiotensin-aldosterone system.

4. Immunity and Tumors

Animal and cell experiments have shown that vitamin D can promote cell differentiation, inhibit tumor cell proliferation, and has anti-inflammatory, pro-apoptotic, and angiogenesis-inhibiting properties. However, large-scale randomized controlled studies are still needed to confirm the correlation between vitamin D and tumors.

04

What should I do if I am deficient in vitamin D?

1. Increase sunlight

It is recommended that people at high risk of vitamin D deficiency expose their skin to sunlight for a certain period of time to promote the synthesis of vitamin D. It is necessary to avoid using sunscreen, glass, and umbrellas. Of course, strong sunlight should also be avoided to prevent skin burns.

2. Eat foods rich in vitamin D

When supplementing your diet, give priority to foods containing vitamin D, such as deep-sea fish, cod liver oil, mushrooms, egg yolks, etc.

Vitamin D content in some foods

3. Vitamin D supplement

The recommended vitamin D intake for residents of all ages and the recommended vitamin D supplementation for people at high risk of vitamin D deficiency are as follows. In addition, it is recommended that pregnant and lactating women should supplement vitamin D at 1500~2000 IU/d.

Recommended dose of vitamin D supplement (unit: IU/d)

4. People with vitamin D deficiency should seek medical attention immediately

It is recommended that people with vitamin D deficiency seek medical attention promptly, screen for comorbidities, and follow doctor's orders for timely treatment and follow-up. Excessive vitamin D supplementation may lead to elevated urinary calcium, and persistent urinary calcium exceeding 10 mmol/d may increase the risk of kidney stones and renal calcium salt deposition.

References:

[1] Chinese Medical Association Osteoporosis and Bone Mineral Disease Branch. (2018). Consensus on the clinical application of vitamin D and its analogs. Chinese Journal of Endocrinology and Metabolism, 34(3), 14.

[2] Bone Metabolic Disease Group of the Geriatrics Branch of the Chinese Medical Association. (2018). Expert consensus on the clinical application of vitamin D in the elderly (2018). Chinese Journal of Geriatrics, 037(009), 953-961.

[3] Chinese Nutrition Society Bone Nutrition and Health Branch, & Chinese Medical Association Osteoporosis and Bone Mineral Disease Branch. (2021). Expert consensus on nutrition and exercise management for patients with primary osteoporosis. Chinese Journal of Endocrinology and Metabolism, 36(8), 643-653.

[4] Holick MF, Binkley NC, Bischoff-Ferrari HA, Gordon CM, Hanley DA, Heaney RP, Murad MH, Weaver CM; Endocrine Society. Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2011 Jul;96(7):1911-30.

Source: Department of General Medicine, Run Run Shaw Hospital

The cover image of this article is from the copyright library

Reproduction of image content is not authorized