The One Supplement You Should Never Go Without

“D” is for Depression and Dementia

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A friend recently asked me what I would choose if I could only take one supplement. Vitamin D3, I replied, without hesitation.

This raised an eyebrow from my friend, who was expecting something along the lines of vitamin C (winter’s coming) or a multi vitamin and mineral (covering all bases).

Is that for your old bones? She asked, somewhat cheekily.

No! I responded. For my brain.

Beyond bones

Vitamin D may be associated with bone health, but there is so much more to this hormone-like vitamin. When it comes to the brain, it protects neurons from damage and is involved in the transmission of messages. It is essential for the regulation of healthy mood and memory.

A broad spectrum of neurological disorders has been linked to vitamin D insufficiency. These disorders include depression, schizophrenia, dementia (including Alzheimer’s disease), and Parkinson’s disease.

“The likelihood of having depression in vitamin D deficient persons is significantly higher compared to those with adequate vitamin D status.”

And the likelihood of experiencing depression during the winter months is greater still. Seasonal affective disorder (SAD) descends like heavy fog in winter. It usually begins in the autumn and lasts until spring, though in some cases it can persist throughout the year. It is characterised by reduced production of the neurotransmitter serotonin, and vitamin D is believed to play a role in serotonin activity.

As we age, vitamin D deficiency can affect the brain in other ways too. A number of studies have revealed that in the elderly it can manifest as reduced cognitive function. One study of over 1,600 elderly adults who were monitored for over five and a half years found that vitamin D deficiency was associated with “a substantially increased risk” of dementia, including Alzheimer’s.

Light on a pandemic

Vitamin D3 is made in the skin in the presence of sunlight, or more specifically, on exposure to solar ultraviolet B (UVB). It is converted in the body to 25(OH)D, the form of vitamin D that circulates in the blood.

You can already see how deficiency of this vitamin occurs so easily.

The further north you are, the less vitamin D you make. It’s all down to something called the Zenith angle, the angle of sunlight as it reaches the Earth’s surface. Time of day, time of year, and latitude all affect the Zenith angle. If you are on a northern latitude of 37º or higher, you stop making vitamin D in October. Those of you living in New York are on 40º. London is on 51º, Edinburgh 55º.

Although the liver can store some vitamin D, supplies are limited. By the end of October, they’ve usually run out.

You need help. We all do.

The extent of vitamin D deficiency across populations is alarming and has been described as a pandemic, common in all age groups. An estimated one billion people in the world are deficient. Over two-thirds of people in the US and Canada have ‘suboptimal’ levels. Figures for people living in the UK are similar. In Britain, deficiency rises to 90% during spring and winter.

Certain groups are especially vulnerable: breastfeeding infants, the elderly, those with limited sun exposure, people living on a high latitude, and those with dark skin.

Dark-skinned people need about five times as long as the fair-skinned to produce vitamin D. That’s down to the pigment melanin, which blocks absorption of UVB. Sunscreens do something very similar. Sunscreens with a protection factor of 8 can decrease vitamin D3 synthesis by 95%; SPF sunscreen 15 decreases synthesis by 98%.

Vitamin D deficiency affects up to 90% of the elderly population. People over the age of 60 require three to four times more sun exposure than people under 20. That’s because elderly people have decreased 7-dehydrocholesterol, a substance required to make vitamin D in the presence of sunlight.

Obesity is also an issue. Studies frequently show that high adiposity, or fat storage, blocks the release of stored vitamin D. The higher the BMI of an individual, the lower the level of vitamin D circulating in blood.

We all have a big vitamin D-shaped hole in our lives, and it’s one we unwittingly made for ourselves.

Perhaps our first big mistake was leaving equatorial East Africa, our ancestral home, where we once enjoyed year-round wall-to-wall sunshine. That was roughly 60,000 years ago.

Our taste for travel meant colder climes and wearing clothes, and therefore much reduced exposure to sunlight.

D is also for diet

Fortunately, we have back-up. There are some, albeit limited dietary sources, the best being oily fish, and fish liver oil.

Salmon is a particularly good source, but only if it is wild. Farmed salmon has just 25% of the vitamin D content of its wild counterpart, which contains approximately 400iu of D3 per 3.5oz — a “typical” serving size.

After oily fish, your next best source is meat, including offal. Meats with a high fat content, such as lamb, tend to have the highest amounts of D3.

And here’s another problem we have created for ourselves. The current obsession with low-fat food aggravates an already egregious situation: vitamin D is fat-soluble, so dietary sources must contain fat for optimal absorption.

See below for more information on this contentious issue.

Why You Should Always Choose the Full-Fat Option

Eggs are also a good source, with the yolk containing almost all the vitamin D. And there’s a big difference between eggs from hens that are free range, and eggs from indoor-reared hens. Free-range eggs contain 3–4 times more vitamin D than non-free-range eggs.

Plant foods (mushrooms) contain only vitamin D2, a form not considered as effective as D3, though still useful. Vitamin D3 is the form synthesized in the body in the presence of sunlight, and is considered the best, most bioavailable form. That’s why deficiency is an even greater issue for anyone who eats a strict plant-based diet.

Trials in humans “have shown administration of D3 is 3 times more potent than D2”.

Some foods are fortified with vitamin D. Fortified foods tend to be highly processed and include breakfast cereals, bread, and dairy milk alternatives, including soy and almond “milk”. Furthermore, they are usually fortified with D2, not D3, though this is often not made clear on the label.

How much do you need?

In the United States, the recommended daily amount (RDA) for adults is 15μg (600iu). In the UK, the RDA is 10μg (400iu).

RDAs are based on estimates and are not a precise science. It doesn’t help either that dosage of this vitamin is sometimes given in μg (micrograms) and other times in IU (international units). For future reference, all you need to know is that one international unit equals 0.025 micrograms. Therefore, 5 μg = 200iu.

Supplements

Where possible, choose D3 supplements, and read those labels carefully. You’ll still find D2 used in many products because it’s cheap and convenient (for manufacturers).

Studies have found vitamin D2 to be much less effective than D3 in supplements.

“These findings question the usefulness of vitamin D2 supplements…. Instead, vitamin D3 should be used for supplementation and fortification purposes”

We need the sun to make vitamin D, a clear indication that humans are built for the sunlit outdoors.

Which presents another dilemma: we are exhorted to cover up, or slather ourselves in sunscreen, because of the risk of skin cancer.

The American Academy of Dermatology recommends that vitamin D should be obtained exclusively from diet and supplements, rather than sun exposure.

The official advice is, however changing in other countries, because of the alarming rates of deficiency.

Here in the UK, Public Health England (now the UK Health Security Agency and Office for Health Improvement and Disparities. (Perhaps they thought it was easier to remember)) changed its policy a few years ago and now recommends that everyone should aim for a short daily burst of sun exposure, without the use of sunscreen.

“… everyone will need to consider taking a supplement in the autumn and winter if you don’t eat enough foods that naturally contain vitamin D or are fortified with it. And those who don’t get out in the sun or always cover their skin when they do, should take a vitamin D supplement throughout the year.”

Avoiding the sun is counterintuitive: humans have a primeval love of warm weather, and merrily strip off to the bare minimum whenever the opportunity to do so presents itself.

The dark months pose an enormous challenge to our mental health, which is why it is vital to ensure that your brain is adequately supplemented with vitamin D3. As I told my friend.