“Suspended lion face

Spilling at the centre

Of an unfurnished sky

How still you stand,

And how unaided

Single stalkless flower

You pour unrecompensed.”

From, “Solar” by Philip Larkin

The heat of the summer shifts all of our habits. We try to find the subtle tells in the afternoon air that suggest whether our patio will be habitable by evening; workout runs get pushed later and later in the hopes we won’t feel the heat of the blacktop through the soles of our feet; as the summer continues, finding parking in the shade becomes more of a necessity than a bonus. The sun is at the heart of all of these troubles, but we all know we will miss this a bit during a cloudy stretch in February.

One thing that we can thank the sun for has always been a bit confusing to me. Science tells us that absorbing sunlight into our bodies provides us with vitamin D, which is necessary for our wellbeing. Science also has some wild things to say about light, such as how it seems to act as both a particle and a wave. Visible “light” is really only part of a larger spectrum that is invisible to us. Plus, the whole speed thing. So with all of this going on, is light also carrying some nutrition with it as it flies along through space? Is the vitamin lying dormant in us and only becomes usable when exposed to sunlight? Are we actually like plants who use light in the process of photosynthesis to power themselves?

Well, it’s not quite any of those. When a plant absorbs light, it is using that energy to produce sugars for itself and, as a byproduct, oxygen for us. When sunlight hits our body, we absorb some of that energy as well, but its uses come in much farther down the line in a digestive process, and we don’t produce fresh oxygen into the air. While our skin goes through a number of processes when exposed to light, for the purpose of vitamin D, what we are actually interested in is the presence of cholesterol in our skin, which breaks down into useful compounds such as vitamin D. That’s right, cholesterol – which many of us have been told to watch out for. This must be what they mean when they say “good cholesterol.” The vitamins produced here are then stored in the body’s fat cells and will be pumped into our system as those cells are absorbed. The vitamins themselves are useful for maintaining our immune system, helping us break down calcium and prolonging muscle health.

Before you decide to invest in a tanning booth to get more vitamin D, it’s important to note that we also consume vitamin D in many animal-based foods, and plenty of supplements are available if you have reason to believe you are insufficient. These other sources heavily outweigh the amount of vitamin D produced through sun-exposure, so while this is an interesting little note in the orchestra of how our body maintains homeostasis with the world around us, it can sometimes be nice to have one thing to put in a hot summer’s column. Part of enjoying the sun is always dependent on limiting your prolonged exposure, using sunscreen when necessary and staying hydrated.

Are you interested in changing the world by studying the relationships between humans and their economic, social and natural environments? Life University’s Bachelor of Science degree in Human Ecology might be a “natural” fit for you!