The British Medical Journal recently published a letter, expressing what they considered was overwhelming evidence supporting the benefit of having optimal blood levels of vitamin D to fight a Covid-19 infection. So, what are optimal blood serum levels and does this directly correlate to dietary intake? First of all, not all countries recommend the same dietary intake, but most advise about 800 IU/d for an adult. Just for info, UK guidance is usually 400 IU/d, although the BMJ are now suggesting between 4-5000 IU during the Covid-19 pandemic.
A substantial increase!
Before you rush to take high dose supplements, I advise you to have blood serum levels checked, because too much vitamin D may also cause problems.
Optimal levels of 25-hydroxyvitamin D should be between 125 – 175 nmol/L.
Tests cost less than a night out and I doubt you are partying much at the moment! Why not spend it on something you will gain benefit from instead? I can arrange various biochemical tests, so if you would like help with this, just email me. Nutritionally speaking, unless you are being fastidious about calculating dietary intake, every single day, it is highly unlikely you are eating enough, let alone metabolising this into the active form. I’ll go through that in more detail, further on. Now, as you probably already aware, you can buy Vitamin D in two versions, D2 and D3.
D2 is from plants and D3 is from animals.
I’m not going to discuss getting vitamin D3 from sunlight, because the chances of you prancing around naked on a daily basis (until at least next summer), is pretty slim. Scientists are still arguing about which is the best supplement form of vitamin D, but we’ll just let them carry on for the time being, because whether you take vitamin D2 or D3, your body still has to convert it into a hormone called calcitrol (also called calcitriol) which has major benefits for bones, cardiovascular health and immunity and this happens via a two step process:
1) In the liver
2) In the kidneys
How efficiently you manage that conversion depends on a number of factors, such as the health of your gut, the health of your liver and kidneys, what drugs you are taking, your genetics and whether you have a healthy, balanced diet that includes other vitamin D cofactors, although I’m not going to go into them today. How well calcitrol balances levels of calcium and phosphorus in your body (for bone and heart health), also depends on how healthy your gut is, in particular intestinal health.
Yes, but what about immunity?
Calcitrol also works together with retinol to support immunity. How efficiently this marriage works, depends on whether you have an adequate intake of vitamin A (from animal source). Or, if you are vegan, it depends on whether you are sufficiently converting beta-carotene from plants to retinol (vitamin A). Gene snps may play a role here and can also be easily checked via testing. It is worth remembering, that both D and A are fat soluble vitamins, this means that if you are eating a very low fat diet, or taking weight loss tablets such as Alli, it is likely you have reduced levels in your body. Ok then, so if you want to eat more vitamin D, these are the best options…
For vegans/plant eaters the choices of vitamin D include:
Mushrooms that state on the pack ‘high vitamin D’ have significantly more D than regular mushrooms (100g = 1048 IU compared to 7 IU). If you can’t find these, go for regular mushrooms, but pop them on the windowsill gill side up, in the morning, for a few hours.
Any vegan product, such as plant milk that states ‘fortified with vitamin D.