Our community gardening programme is based on the research showing that not only engaging in gardening and connecting with individuals, but simply being outdoors absorbing sunlight to make vitamin D, benefits us our mental and physical health in a number of ways.
Vitamin D is our sunshine vitamin. Sunlight-induced vitamin D production is vital for maintaining bone health, supporting immune function, promoting cardiovascular health and regulating mood. Adequate sunlight exposure and sufficient vitamin D levels play significant roles in regulating circadian rhythms, improving sleep quality, and potentially reducing the risk of sleep disorders.
We get vitamin D from the sun through a process that starts when sunlight, specifically ultraviolet B (UVB) rays, hits our skin and, with the help of the liver and kidneys, converts a type of cholesterol into active vitamin D – scroll down to see how it works.
Regular sensible sun exposure is essential for maintaining adequate vitamin D levels. Factors like skin tone, geographic location, and time of year affect how much vitamin D you can produce from sunlight. Too much sun exposure can increase the risk of skin damage.
Sunlight and Physical Health
Bone Health Vitamin D is crucial for calcium absorption in the gut, which helps maintain healthy bones and teeth. A deficiency in vitamin D can lead to bone disorders such as rickets in children and osteomalacia (‘softening of the bones’) or osteoporosis in adults. Research shows that adequate vitamin D levels are essential for bone mineralisation and strength. For instance, a study published in The New England Journal of Medicine found that vitamin D supplementation reduces the risk of fractures in older adults by enhancing bone density and strength (Bischoff-Ferrari et al., 2004).
Immune Function Vitamin D plays a vital role in modulating the immune system. It helps activate immune defence and has been shown to reduce the risk of infections and autoimmune diseases. A systematic review in The Lancet Diabetes & Endocrinology highlights that vitamin D deficiency is associated with an increased risk of various infections and autoimmune conditions, such as multiple sclerosis and type 1 diabetes (Murai et al., 2017).
Cardiovascular Health Adequate vitamin D levels are linked to better cardiovascular health. Vitamin D deficiency has been associated with an increased risk of cardiovascular diseases, such as hypertension, heart attack, and stroke. A meta-analysis in The American Journal of Clinical Nutrition found that vitamin D supplementation is associated with a reduced risk of cardiovascular events (Wang et al., 2010).
Sunlight and Mental Heath
Mood Regulation Vitamin D influences mood and mental health. Several studies have found a correlation between low levels of vitamin D and higher rates of depression. Research published in JAMA Psychiatry found that vitamin D supplementation can have a positive effect on mood, particularly in individuals with low levels of the vitamin (Anglin et al., 2013).
Sleep improvement Since vitamin D is involved in mood regulation, which affects sleep, its impact on mental health can indirectly influence sleep patterns. Research has shown that improving vitamin D levels can help alleviate symptoms of depression, which in turn may lead to better sleep outcomes (Anglin et al., 2013). There is evidence suggesting that adequate levels of vitamin D may improve sleep quality. Research published in The Journal of Clinical Sleep Medicine found that low vitamin D levels are associated with poorer sleep quality and shorter sleep duration. The study highlighted that vitamin D might influence sleep through its role in regulating mood and inflammatory processes that affect sleep (Zhao et al., 2014).
A study published in Sleep Medicine Reviews indicates that natural light exposure, particularly in the morning, plays a critical role in maintaining a healthy sleep-wake pattern (Chellappa et al., 2011). Exposure to natural sunlight helps regulate the circadian rhythm, which is the body’s internal clock that controls sleep-wake cycles. Sunlight exposure in the morning helps synchronise this clock, promoting alertness during the day and facilitating sleep at night.
Insufficient vitamin D levels have also been linked to an increased risk of sleep disorders. A study in Sleep journal found that vitamin D deficiency is associated with an increased prevalence of sleep disturbances and obstructive sleep apnea (Baron et al., 2013). Ensuring adequate vitamin D levels may help mitigate these issues.
Sunlight to Sunshine Vitamin D
Here’s how it works:
UVB Rays Penetrate the Skin When your skin is exposed to UVB rays from the sun, a type of cholesterol in the skin called 7-dehydrocholesterol absorbs the UVB light.
Conversion to Pre-Vitamin D The absorbed UVB radiation converts the 7-dehydrocholesterol into previtamin D3.
Conversion to Active Vitamin D: Previtamin D3 then undergoes a heat-dependent transformation in the skin to become vitamin D3 (cholecalciferol).
Activation in the Liver and Kidneys: Once vitamin D3 enters the bloodstream, it’s transported to the liver, where it is converted into calcidiol (25-hydroxyvitamin D). It then moves to the kidneys, where it’s further converted into the active form of vitamin D, known as calcitriol.
This active form of vitamin D is what the body uses to regulate calcium and phosphorus levels, which are crucial for bone health, immune function, and other processes. This understanding is grounded in decades of scientific studies in biochemistry, dermatology, and nutrition, including those examining vitamin D’s role in bone health, immune function, and its potential links to various diseases. Research on our sunshine vitamin D continues, particularly on the health effects of deficiency and optimal sun exposure levels.
