Vitamin D – An all round superhero

We've had the Autumn equinox, the nights are drawing in, the days of feet being confined to socks are just around the corner and that yellow ball in the sky will become harder to find.

Apart from affecting our mood the lack of sun can have other downsides. You see the sun is our best source of vitamin D (providing it's not hiding behind clouds).

You may have already heard about the importance of vitamin D but I’m going to reiterate it as it is such an important nutrient and has so many vital roles. It is commonly known for its importance in bone growth by maintaining proper calcium levels in our blood through absorption through the gut but vitamin D also influences over 2000 different genes in the body.

First of all vitamin D is not actually a vitamin, it is a pro-hormone because your body can synthesize it. However, vitamin D deficiency is a major health problem in the northern hemisphere. In fact, if you live in a country that is 25 degrees north of the equator such as the UK, the whole of Europe and North America, you won’t be getting enough vitamin D through sunlight the majority of the time.

I would highly recommend you have your levels tested by asking your doctor for a Serum 25-Hydroxyvitamin D test. If your levels are lower than 32ng/mL you are at risk of osteoporosis and bone fractures and possibly hypertension, several cancers and multiple sclerosis. But I don't want to scare you, it's easily fixed once you know.

Now I'm going to get all sciencey on you but bear with me.......

Vitamin D is essential for a healthy immune system and can protect us against infectious diseases like tuberculosis. It also induces the expression of p21. P21 is a cyclin-dependent kinase inhibitor which stops tumour cells from growing. It is also important to cardiovascular health.

It's produced from ultraviolet light hitting the 7-dehydrocholesterol molecule in the skin. The pre-vitamin D molecule travels in the blood to the liver, where it is converted to 25-hydroxyvitamin D which is the form that circulates in the blood and is tested for to see if you are deficient.

25-hydroxyvitamin D is then converted in the kidneys to the active compound, 1,25 dihydroxyvitamin D or calcitiol, which binds to receptors and turns on genes.

Vitamin D is important for maintaining a balanced T lymphocyte (your killer cells) repertoire. An imbalance could lead to increased levels of inflammation and chronic inflammation contributes to the development of many diseases such as cardiovascular disease. A level of 30ng/ml or higher may be necessary for optimal immune response, function and control of the inflammatory response.

It also helps to maintain muscle strength, improve fertility, help control weight, help prevent strokes and neurological disorders like dementia. There are also correlative studies suggesting that vitamin D may improve cognitive function in the elderly.

Vitamin D can help kill pathogens like bacteria and viruses by turning on genes in macrophages and neutrophils (cells of the innate immune system). These genes make small ninja like peptides called cathelicidin that punch holes in the pathogen’s membrane and disable it. There are a lot of defences that work together to battle pathogens but cathelicidin is critical.

You also need correct vitamin D levels in order to utilise calcium. Even if you are eating enough calcium, if you are deficient in vitamin D your body will not be able to use that calcium.

And to top off vitamin D's accolades, more than 2500 published studies confirm that vitamin D plays a role in cancer prevention.

So as you can see, it's not just about strong bones, yet more than 1 billion people worldwide are chronically deficient in this vital nutrient.

Synthesizing vitamin D in the skin depends on several factors such as where you live and the season. Your shadow needs to be shorter than you in order for you to be able to get vitamin D from sunlight. Sunscreen blocks harmful rays from sunlight but it also blocks vitamin D being synthesised. The darker your skin the longer you need to be in the sunlight so if you are of dark skin and live in a northern hemisphere you are especially at risk of being deficient also as you get older your skin becomes less efficient at synthesising vitamin D.

Now, you still need to practice caution when going into the sun. Spend a short amount of time without sunscreen with your arms, face and legs. Don't go out and fry yourself, just be aware of your limits. You do not want to burn!

Which foods contain Vitamin D?

Unfortunately food is not the best source of this nutrient. There are a few foods that you can get vitamin D from such as fish, like salmon, herring and sardines. You can also get it from wild or cultivated mushrooms exposed to sunlight and eggs. Vegetarians and vegans are at further risk of deficiency due to the lack of vegetarian/vegan sources of vitamin D.

To make sure my levels are maintained at all times, I take 2000iu of vitamin D3(cholecalciferol) per day in supplement form, which is the optimal level for an adult. It’s important to keep sufficient vitamin D levels in the blood and its better to keep levels consistent rather than go up and down so supplementing daily all year round is advisable. There is no issue of toxicity at this level, you would have to take 10,000 iu or more per day long term to cause toxicity. Given the right conditions, our bodies are capable of synthesising about 20,000 iu/day through sun exposure. As with all supplements, make sure you take a pharmaceutical grade supplement.

Statin drugs can also deplete levels of vitamin D3. As statins lower cholesterol, statin users may not have enough cholesterol to synthesis sufficient vitamin D.

So, your first task is to know your levels. Go and get your vitamin D tested then look at how you can get those levels up into the optimal range and if you want further advise on this get in touch.

For those of you that would like to read more about vitamin D, here are a handful of recent studies from over 3900 published studies around vitamin D.

VITAMIN D3 SUPPLEMENTATION IN PATIENTS WITH CHRONIC OBSTRUCTIVE PULMONARY DISEASE [MARTINEAU, 2014]

VITAMIN D PROMOTES VASCULAR REGENERATION [WONG, 2014]

VITAMIN D AND DEPRESSION: A SYSTEMATIC REVIEW AND META-ANALYSIS COMPARING STUDIES WITH AND WITHOUT BIOLOGICAL FLAWS. [SPEDDING, 2014]

EFFECT OF VITAMIN D SUPPLEMENTATION ON ANTIBIOTIC USE: A RANDOMIZED CONTROLLED TRIAL. [TRAN, 2014]

VITAMIN D AND RISK OF CAUSE SPECIFIC DEATH: SYSTEMATIC REVIEW AND META-ANALYSIS OF OBSERVATIONAL COHORT AND RANDOMISED INTERVENTION STUDIES [CHOWDHURY, 2014]

META-ANALYSIS OF ALL-CAUSE MORTALITY ACCORDING TO SERUM 25-HYDROXYVITAMIN D [GARLAND, 2014]

LOW VITAMIN D LEVEL IS AN INDEPENDENT PREDICTOR OF POOR OUTCOMES IN CLOSTRIDIUM DIFFICILE-ASSOCIATED DIARRHEA [WANG, 2014]

AVOIDANCE OF SUN EXPOSURE IS A RISK FACTOR FOR ALL-CAUSE MORTALITY: RESULTS FROM THE MISS COHORT [LINDQVIST, 2014]

25-HYDROXYVITAMIN D IN THE RANGE OF 20 TO 100 NG/ML AND INCIDENCE OF KIDNEY STONES [NGUYEN, 2014]

PREDIAGNOSTIC CIRCULATING VITAMIN D LEVELS AND RISK OF HEPATOCELLULAR CARCINOMA IN EUROPEAN POPULATIONS: A NESTED CASE-CONTROL STUDY [FEDIRKO, 2014]

PLASMA VITAMIN D CONCENTRATION INFLUENCES SURVIVAL OUTCOME AFTER A DIAGNOSIS OF COLORECTAL CANCER [ZGAGA, 2014]

META-ANALYSIS OF VITAMIN D SUFFICIENCY FOR IMPROVING SURVIVAL OF PATIENTS WITH BREAST CANCER [MOHR, 2014]

REDUCED 25-HYDROXYVITAMIN D AND RISK OF ALZHEIMER'S DISEASE AND VASCULAR DEMENTIA [AFZAL, 2014]

VITAMIN D AND THE RISK OF DEMENTIA AND ALZHEIMER DISEASE [LITTLEJOHNS, 2014]

POST-HOC COMPARISON OF VITAMIN D STATUS AT THREE TIME POINTS DURING PREGNANCY DEMONSTRATES LOWER RISK OF PRETERM BIRTH WITH HIGHER VITAMIN D CLOSER TO DELIVERY [WAGNER, 2014]

VITAMIN D IN FETAL DEVELOPMENT: FINDINGS FROM A BIRTH COHORT STUDY [HART, 2014]

VITAMIN D AND PRE-ECLAMPSIA: ORIGINAL DATA, SYSTEMATIC REVIEW AND META-ANALYSIS [HYPPONEN, 2014]

GENETICALLY LOW VITAMIN D CONCENTRATIONS AND INCREASED MORTALITY: MENDELIAN RANDOMIZATION ANALYSIS IN THREE LARGE COHORTS [AZFAL, 2014]

GUIDELINES FOR OPTIMIZING DESIGN AND ANALYSIS OF CLINICAL STUDIES OF NUTRIENT EFFECTS [HEANEY, 2014]

 

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