Dr. Harsha G N, Consultant- Orthopaedics, Aster Whitefield Hospital
Most of us have grown up believing that a brisk morning stroll, taken just as the sun rises, is sufficient to strengthen our bones and increase our vitamin D levels. It makes sense: the air is fresh, the heat is low, and the early hours feel naturally healthful. But, according to scientists, this generally held belief does not convey the whole story. When it comes to creating stronger bones, the timing of your sun exposure is critical—and it is the afternoon sun that helps your body produce the vitamin D it requires.
This topic is around two key nutrients: calcium and vitamin D. Calcium is obtained through the foods we consume, such as dairy products, leafy greens, and almonds. However, calcium cannot operate alone. The body needs vitamin D to absorb calcium in the intestine. Even a calcium-rich diet will not prevent bone loss if vitamin D levels are low. This is why learning the proper approach to getting enough vitamin D is critical.
When exposed to sunlight’s ultraviolet B (UVB) rays, the skin creates vitamin D. These UVB rays cause a natural reaction in the skin, resulting in the synthesis of vitamin D, which aids calcium absorption. However, not all sunlight is equal. According to research, UVB rays are most intense between 12 and 3 p.m., when the sun is at its highest position in the sky. UVA rays dominate early morning sunshine between 6 a.m. and 7.30 a.m., but they do not contribute to vitamin D production. This means that a morning stroll, while beneficial for other reasons, offers little to boost your vitamin D levels.
Could you please let me know how much sun exposure is necessary? Experts normally recommend exposing the face, arms, and legs to sunlight for 20 to 30 minutes twice or three times each week during moderate weather. This should be done without sunscreen, allowing UVB rays to penetrate the skin. However, balance is essential. Prolonged, unprotected exposure to direct sunlight can cause sunburn and raise the long-term risk of skin cancer and other skin damage. The goal is to spend just enough time in the sun to produce vitamin D without damaging the skin.
The repercussions of low vitamin D levels can be severe. Osteoporosis, a disorder in which bones grow weak and fragile, is frequent among older adults, particularly women following menopause. However, doctors are now seeing an increase in vitamin D deficiency and early bone loss among younger women as well. Sedentary lifestyles, long hours spent indoors, poor nutrition, and inadequate exposure to sunlight all contribute significantly. Severe vitamin D deficiency in young people can lead to osteomalacia, a condition in which bones soften and become more prone to fracture. Urban professionals, such as IT workers, who rarely go outside throughout the day, are increasingly vulnerable.
How about supplements? Although vitamin D and calcium supplements are readily available, self-medication is not recommended. Vitamin D may not function properly without appropriate calcium, and taking either nutrient in the wrong dose can be harmful. It is always advisable to get checked first, and then only take supplements if your doctor prescribes them.
If you have been relying on morning sunlight to meet your vitamin D requirements, it may be time to reconsider your habit. One of the simplest methods to safeguard your bones and prevent early wear and tear is to schedule brief, safe exposure to afternoon sunshine a few times per week. This habit, when combined with a well-balanced diet and frequent physical activity, can help you maintain excellent bone health.
So, for your daily dose of sunshine, make sure to go outside when the sun is actually helping you.