Vitamin D: Abundant but Easily Deficient

Vitamin D: Abundant but Easily Deficient

Vitamin D offers numerous health benefits, including aiding calcium absorption, supporting bone formation, and promoting the health of muscles, lungs, brain, heart, nervous system, and immune system. However, despite being a country with abundant sunlight, many Thais are deficient in vitamin D. This paradox occurs because the human body synthesizes vitamin D through the skin when exposed to sunlight, but modern lifestyle changes have led people to spend more time indoors, reducing sun exposure. Vitamin D deficiency not only weakens bones but is also linked to chronic diseases such as diabetes, cancer, infections, and allergies.

Why Does the Body Need Vitamin D?

Vitamin D plays a crucial role in:

• Calcium and phosphorus absorption: It helps maintain proper mineral levels in the blood, which are essential for bone and tooth development, preventing osteoporosis and bone loss.
• Regulating parathyroid hormone (PTH): Prevents excessive bone resorption.
• Supporting immune function: Helps defend against infections caused by bacteria and viruses.

If the body lacks vitamin D, calcium absorption in the intestines decreases, leading to lower bone mass and an increased risk of fractures. Severe deficiency may also result in:

• Low blood calcium and phosphorus levels
• Rickets in children
• Osteoporosis in adults
• Increased susceptibility to infections

Risk Factors for Vitamin D Deficiency

1. Insufficient sun exposure:
   • Avoiding sunlight or excessive use of high-SPF sunscreen, which blocks UV rays needed for vitamin D synthesis.
2. Air pollution and smog:
   • Reduces the penetration of ultraviolet (UV) rays, limiting vitamin D production in the skin.
3. Inadequate dietary intake:
   • Foods rich in vitamin D include fatty fish (sardines, trout, tuna, salmon, mackerel), milk, and fortified cereals.
4. Elderly individuals:
   • Natural aging reduces the body’s ability to synthesize vitamin D, and older adults spend less time outdoors.
5. Overweight individuals:
   • Fat storage reduces the availability of vitamin D in the body.
6. Pregnant and breastfeeding women:
   • Increased nutritional needs make them more susceptible to deficiency.
7. People with darker skin tones:
   • More melanin reduces the skin’s ability to produce vitamin D.
8. Individuals with digestive disorders:
   • Conditions like Crohn’s disease or chronic pancreatitis impair fat absorption, which is necessary for vitamin D metabolism.
9. Chronic kidney disease (stage 3-4):
   • The kidneys play a role in converting vitamin D into its active form.

Recommended Daily Intake of Vitamin D for Thais

According to Thailand’s nutritional guidelines, the recommended daily intake of vitamin D varies by age:

• Infants (under 12 months): 400 IU (10 mcg)
• Children and adults (under 70 years): 600 IU (15 mcg)
• Elderly (over 70 years): 800 IU (20 mcg)
• Women planning pregnancy: 400-600 IU (10-15 mcg)
• Pregnant women at high risk of deficiency: 2,000-4,000 IU (50-100 mcg)

How to Know if You Are Vitamin D Deficient

Vitamin D deficiency symptoms are often vague and non-specific, including:

• Fatigue and weakness
• Bone pain or unexplained body aches
• Hair loss
• Frequent infections
• Depression or anxiety
• No symptoms at all

The best way to confirm vitamin D deficiency is through a blood test measuring 25-hydroxyvitamin D [25(OH)D] levels. The classification of vitamin D levels is as follows:

• Deficient: Less than 20 ng/mL
• Insufficient: 20-30 ng/mL
• Sufficient: More than 30 ng/mL

How to Prevent and Address Vitamin D Deficiency

1. Increase Sun Exposure

   • Engage in outdoor activities for at least 15 minutes, 2-4 times per week during early morning (6:00-8:00 AM) or late afternoon (4:00-6:00 PM) to allow sunlight to convert cholesterol into vitamin D.

2. Eat Vitamin D-Rich Foods

   • Fish: Tuna, mackerel, salmon
   • Animal sources: Cod liver oil, liver, egg yolks
   • Plant-based sources: Mushrooms

3. Vitamin D Supplements

   • Doctors may recommend vitamin D supplements based on individual needs.

4. Regular Health Check-ups

   • Periodic blood tests to monitor vitamin D levels and adjust supplementation if necessary.

The Importance of Adequate Vitamin D

Maintaining optimal vitamin D levels not only strengthens bones but also reduces the risk of infections and may lower the severity of complications from illnesses, including COVID-19. Ensuring sufficient vitamin D intake is a simple yet crucial step toward overall health and well-being.