Summer gives you a huge vitamin D boost. What happens now?

After months of longer days and more time outdoors, many of us have enjoyed boosting our vitamin D naturally. But as the days shorten and the sun sits lower in the sky, that window starts to close.

Vitamin D is essential for everything, from your immune system to blood sugar balance. You need it for your heart, your brain, your bones, and your reproductive health. Notably, vitamin D’s functions are also linked to cancer prevention and skin health.

As 1 in 6 adults in the UK are seasonally very low in vitamin D, and many more have less than optimal levels, what happens when all that summer sunshine begins to disappear? And while there are still bright days to enjoy, how can you make the most of them without putting your skin at risk?

Here’s how you can stay safe in the sun, make the most of the vitamin D opportunity while it lasts, and think about keeping your levels topped up as we head into the darker months.

Spend a short time in the sun with no protection

Bear with me on this – I know it seems mad. But a little exposure is OK. One study worked this out to be about nine minutes a day at high noon in the south of the UK, or 13 minutes in Scotland, and even longer for those with dark skin. Probably less if you have fair skin though, so just be sensible about this.

This is with at least a third of your skin exposed to the sun (e.g. wearing shorts and a T-shirt), so you’ll need longer if it’s just your hands and face.

It’s important to do this without going red or burning, so if you need to spend a shorter time in the sun, consider exposing more skin during that time.

Make sure the sun is high enough in the sky

The sun’s UVB rays convert a substance in your skin to vitamin D. This is then converted to another form of vitamin D in your liver, and then to another one in your kidneys.

You only get enough of these UVB rays that kickstart the whole process when then sun is at least 50 degrees above the horizon. In the UK, that means between April and September, and even then, just for part of the day. So as autumn approaches, a bright or even warm day doesn’t necessarily mean you’re still making useful amounts of vitamin D.

A rough way of telling if the sun is high enough in the sky is to look at your shadow. If your shadow is longer than you, you’re not getting the rays you need.

Cover up the rest of the time

Once you’ve had your rays for the day, cover up! Either by staying in the shade, or with cool, natural fabrics, or with sun blocks and suntan lotions.

Remember that one application of sun cream won’t last all day, so check the label to see how frequently you need to top up. Especially if you’re swimming.

Use coral-friendly suntan products

There are ingredients in many standard sun creams and sun blocks that kill coral reefs – and often aren’t that great for your skin either. These include octocrylene, oxybenzone and various parabens, as well as nano particles.

Coral-reef and skin friendly sunscreens are mineral-based, using zinc oxide or titanium dioxide. These can sit on your skin and leave a white residue, however. This doesn’t affect its performance, but a lot of people don’t like the feeling or the look. So companies have developed nano particles of these same mineral compounds, that function in a similar way but without the residue.

Unfortunately, these nanoparticles are problematic for coral reefs and sealife. There is ongoing research and debate as to whether they are safe for human use.

Get your vitamin D levels checked

Did you know you can get your vitamin D levels checked? You do now.

There are mixed scientific opinions about how and when we can make vitamin D and what affects it, however, and there are so many variables at play, the only sure-fire way to make sure you are getting enough vitamin D is with blood tests.

Your GP may do this for free, which is the best way to be sure of accuracy, or you can get very simple home bloodspot tests. So what should your blood serum level of vitamin D be?

The NHS says at least 25nmol/L, but this is based on just prevention of rickets, which is a pretty low bar. In the US and elsewhere, the minimum is 50nmol/L, and many experts would argue you need at least 90nmol/L (but no more than 200nmol/L).

Top up with supplements if necessary

There are so many vitamin D capsules, sprays, and liquid drops available now, and most of them are similar in quality. The amount you need will depend on what your blood serum levels are.

NHS guidelines say everyone should consider taking at least 10 micrograms of vitamin D daily during autumn and winter because in the UK we cannot make enough from sunlight between roughly October and early March. Certain higher-risk groups should consider it year-round.

Include oily fish and other foods

You can get good levels of vitamin D from your diet if you eat plenty of oily fish. There’s also a little in eggs and mushrooms, but probably not enough, so don’t rely on those alone.

Have a carotenoid and antioxidant-rich diet

Carotenoids are a group of plant nutrients that help to protect your skin from sun damage. They include the alpha carotene and beta carotene you get in carrots and other orange vegetables, the lutein and zeaxanthin from yellow and green leafy vegetables, as well as the astaxanthin that make salmon and prawns pink.

Many other antioxidant-rich foods will help to prevent tissue and DNA damage too. The easiest way to ensure an antioxidant-rich diet is to eat the rainbow: with perhaps 40% of your mealtimes made up of a variety of vegetables, plus a couple of portions of fruit a day. You can keep varying these through the weeks and seasons.

Keep hydrated

Skin health relies on hydration. It’s not only made largely of water, but it relies on that water to keep nutrients flowing in and to get rid of toxins and waste. If your skin is well hydrated, it can weather the sun more easily.

Kirsten Chick is a Brighton-based Nutritional Therapist and author of Nutrition Brought to Life. Find out more about Kirsten on her website