Why is vitamin D so important
01
Sep

Why is vitamin D so important?

With Winter drawing to end and the welcomed glory of Spring and Summer upon us, it’s a timely reminder to talk about a very important vitamin – vitamin D. You may have heard vitamin D referred to as the Sunshine Vitamin. This is because vitamin D is predominantly obtained from the sun when its UVB rays react with a cholesterol-based precursor naturally occurring in our skin. And whilst there are some food sources of vitamin D such oily fish (salmon, sardines and mackerel), obtaining our requirements from food alone is quite difficult. In fact most adults are unlikely to obtain more than 5%–10% of their vitamin D requirement from dietary sources alone, making (sensible) sun exposure very important. This is especially so at the end of Winter, where vitamin D levels are typically at its lowest.

Did you know that between the end of Summer and the end of Winter, vitamin D levels can drop by 25%?

Why is vitamin D so important?

Vitamin D is involved in numerous functions so ensuring we have adequate levels is essential in optimising health and wellbeing. Some of these of include:

• Bone growth and development. Without sufficient vitamin D, only 15% of dietary calcium and 60% of phosphorus (another important mineral required for bone growth and density) is absorbed. This is particularly important during periods of rapid growth, such as childhood and adolescence as well in older age where there is increased risk of osteoporosis and bone fracture.
• Muscle function and strength
• Metabolic function, such as regulating insulin secretion which is important for maintaining stable blood sugar levels and energy
• Brain health – it’s needed for the synthesis of neurotransmitters such as serotonin – our ‘happy’ hormone.
• Immune function

Who’s at risk of low vitamin D?

Given sun exposure is our main source of vitamin D, many groups are at higher risk of low vitamin D levels, including:

• People who work in enclosed environments such as office workers
• Individuals who are older or with disabilities living in residential care
• People with darker skin pigmentation as the UVB rays take longer to penetrate the melanin in their skin to make vitamin D
• People who are veiled in clothing due to religious or personal choices
• Overweight individuals
• Pregnant women and breastfed infants with mothers with low vitamin D

How much sun exposure should we be getting?

During the summer time, for moderately fair-skinned people a walk with arms exposed for 6-7 minutes on most days is recommended to maintain healthy vitamin D levels. During the Winter, this increases to 7-40 minutes with as much bare skin exposed as feasible. Individuals with darker skin will require twice to six times as long.

Do note though…

Whilst the sun the most important source of vitamin D, it’s important to take a balanced approach to sun exposure as the heightened UV levels in the warmer months can increase risk of skin damage – so be mindful of your exposure by adhering to the guidelines and using good sun protection (sunscreen, clothing, hat and shade) at all other other times.

With some amazing months ahead of us, be sure to get outside and enjoy the magical and vitamin-D giving sunshine while it lasts!

Reference: Nowson et al 2012, ‘Vitamin D and Health in Adults in Australia and New Zealand: A position statement’, MJA 196:11