Looking after your immune system – part 2

by | Nov 30, 2021 | Blog, Well-Being | 0 comments

Last month I focused on how important Vitamin C was to having a healthy immune system. This month, I want to talk about Vitamin D. 

Why is Vitamin D important?

Vitamin D is a superstar vitamin. More correctly, it’s actually a hormone. If levels are too low, this is bad news for health. Amongst other things,

Like Vitamin C, Vitamin D is a significant micronutrient needed for a healthy immune system. Vitamin D also supports the immune response by stimulating the production of the B- and T-cells which means more antibodies to fight against trouble like viruses. 

Vitamin D deficiency has been shown to correspond to a greater risk of respiratory tract infections, and acute respiratory distress in SARS-CoV-2 infections. A recent large review showed that vitamin D supplementation reduced the risk of cold and flu patients developing acute respiratory infections (ARIs) from 60% to 32%. Similarly, hospital data on early intervention with Vitamin D supplementation in SARS-CoV-2 infections reduced severity of the infection and lowered ICU admissions. 

Research shows you’re 11 times more likely to be depressed if you have low vitamin D, than if you don’t.

Vitamin D can put the brakes on the progression of Alzheimer’s disease.

And deficiency has been implicated in the development of cancer, osteoporosis, rickets in children, asthma, tuberculosis, multiple sclerosis (and other autoimmune diseases), heart disease, diabetes and dental problems.

Looking after your immune system – part 2

How is Vitamin D made?

Vitamin D is produced when the skin is exposed to UVB radiation (from sunlight) a molecule known as 7-dehydrocholesterol (derived from cholesterol) is converted to cholecalciferol, also known as D3. Cholecalciferol can also be obtained from the diet or by supplementation (D3).  It can additionally be obtained from dietary sources (oily fish, eggs and butter).  Vitamin D3 is the form the body uses best and therefore if you are going to take a supplement, make sure it’s Vitamin D3. Vegan dietary sources of vitamin D such as mushrooms provide the D2 form of the vitamin which needs further conversion to D3 by the body. [Murray JPM.Textbook of Natural Medicine. 4th Ed.; 2013.]

Looking after your immune system – part 2

Why might you be deficient?

  • Sun cream. Your body makes vitamin D after contact with the sun’s UV rays but, as we’re a nation of sun cream fanatics (and this covers the skin, blocking the rays of sunlight from getting through), you might not be getting enough straight-up sun.
  • Your skin colour. The darker your skin, the less vitamin D you will make. This is due to the higher levels of melanin in your skin that protect against UV light. By blocking the sun’s rays, it also curbs the body’s ability to make the pre-cursor to the active vitamin D.
  • Nightshift workers, care workers, residents in care homes and anyone else who doesn’t spend much time in the sunlight, including children wearing sun cream all the time and babies. Quite simply, you need the sun on your skin
  • Age. Among other things that go a bit wrong as you get older, your body is less good at turning the rays from the sun into vitamin D. Specifically, the kidneys are less good with age at turning it to the active form of calcitriol. 
  • Kidney or liver disease of any kind also means vitamin D is not converted to the active form. 
  • Tummy troubles. Problems with the digestive system (and I’m not talking about disease here – just an imbalance that may cause anything from a few manageable symptoms to more serious trouble ‘downstairs’) mean the digestive tract does not absorb the vitamin D as well. 
  • Obesity (technically that’s a BMI or body mass index of 30+) has the fat cells in your body hoover up the vitamin D. So then it’s stored – unusable – in your fat cells and is not whizzing around your body in your blood. 
  • Lack of sleep. Just as you need sunlight to make vitamin D, you need sleep to actually use it.
  • Stress. The presence of the stress hormone cortisol reduces the uptake of vitamin D by special vitamin D receptors. It literally sits there, in the body, without being able to be used. What a waste!

10 signs you might have Vitamin D Deficiency

  1. Low immunity
  2. Depression or anxiety (including mood changes or irritability)
  3. Bone softening (low bone density), fractures
  4. Feeling tired all the time/ decreased performance
  5. Muscle cramps and weakness
  6. Joint pain (especially back and knees)
  7. Difficulty regulating your blood sugar levels/ post lunch energy crash
  8. Slow wound healing
  9. Low calcium levels in the blood
  10. Unexplained weight gain

Symptoms like these are commonly overlooked because they don’t feel life threatening, and they’re often dismissed as normal, everyday aches and pains you have to deal with. But you don’t have to put up with these symptoms of ill health!

If any of the above resonates with you, then you should definitely get tested. You might find your GP will do this for you. My experience is that they are usually amenable to this particular test. 

The test is the 25-hydroxy vitamin D test (also known as the 25-OH vitamin D test or Calcidiol 25-hydroxycholecalciferol test). It’s the most accurate way to measure how much vitamin D is in your body.

If you do take a test and you’re very low, you’ll need an intense 4-6 weeks supplementation at a high dose and then re-testing to see the impact it’s had.  There is such a thing as too much vitamin D (known as vitamin D toxicity). You’d have to be going some way to get there, but it is possible, which is why it is essential you know your levels before you start guzzling any supplements. 

Looking after your immune system – part 2

How to up your Vitamin D

  • Eat naturally vitamin D-rich foods like oily fish (salmon, sardines, fresh tuna, trout, halibut, mackerel, etc.), high quality cod liver oil, egg yolks and liver. Do not be fooled into thinking the fortified foods are the same or have similar benefits. Fortified foods (like cereals, margarine and some yoghurts) contain a synthetic version of the vitamin known as D2 (the natural form is D3). Research shows this is less effective at raising levels of vitamin D in the blood 
  • Take a supplement. Public Health England now recommend that everyone should supplement 25ug per day of vitamin during winter months (October- May) as much of the population, especially those north of Birmingham, cannot get access to enough UV light to produce adequate levels of vitamin D during the winter months. You can take a generic 6-800 IU dose as an adult (but not children without consulting your GP).
  • Get yourself some sun. Recommended sunlight exposure is between 10 and 30 minutes a day with no sun cream. It’s hard in the winter but try to get outside if it’s sunny without sun cream on.
  • If getting out in the sun is not an option, sit in front of a light box that supplies 10,000 lux of full-spectrum light for 30 minutes every morning. This is an especially good option for winter months, for night shift. Bit of a faff, but it’s an option.


I specialise in helping women sort out their hormones, fatigue, brain fog, digestive bloating or discomfort, weight or mood problems. My mission, whether working with clients on a 1:1 or in group sessions, is that everyone enjoys the journey.