Vitamin D associated with signficantly reduced risk of death from stroke

Regular readers will know that I have a particular interest in the role of sunlight in health, in large part due to its ability to stimulate vitamin D production in the body. Vitamin D, in turn, has been found to be association with a very wide variety of disease processes including cancer, diabetes, and multiple sclerosis. Back in 2007, one of my blogs focused on the relationship between vitamin D levels and risk factors for cardiovascular disease (e.g. heart disease and stroke). This study found that individuals with relatively low levels of vitamin D were at significantly increased risk of a variety of risk factors including high blood pressure, diabetes, obesity and raised levels of blood fats known as triglycerides.

I was therefore interested to read of a study published this week, that has found a relationship between vitamin D levels and cardiovascular disease [1]. This study involved following 6219 Finnish men and women for an average of about 27 years. In those with the highest levels of vitamin D, risk of death from cardiovascular disease was found to be 24 per cent than in those with the lowest vitamin D levels.

Cardiovascular disease death encompasses deaths due to heart disease and stroke. The authors of this study went further by looking at the relationship between vitamin D levels and these specific causes of death. They found no significant relationship between vitamin D levels and risk of death due to heart attack. However, there was a striking relationship between vitamin D levels and risk of death due to stroke. individuals with the highest vitamin D levels were at a 52 per cent reduced risk of dying from stroke compared to those with the lowest levels.

Now ‘epidemiological’ studies of this nature can only be used to show associations between things, and it is not certain whether optimising vitamin D levels actually reduces the risk of stroke. Ideally, any truly protective role of vitamin D needs to be proven with intervention studies (which, say, assess cardiovascular disease risk in individuals treated with vitamin D or placebo). In the meantime, I continue to attempt to optimise my vitamin D levels. If vitamin D turns out to help prevent stroke, then this optimising my vitamin D levels may turn out to be a very worthwhile endeavour (there is a strong history of stroke in my family).

References:

1. Kilkkinen A, et al. Vitamin D status and the risk of cardiovascular disease death. Am J Epidemiol 2009;170(8):1032-9

14 Responses to Vitamin D associated with signficantly reduced risk of death from stroke

  1. Terry 30 October 2009 at 1:19 pm #

    As a matter of interest, Dr Briffa, what are the UK recognised levels of Vitamin D toxicity? I’m sure one of your correspondents once wrote that she had Kingston Hospital keep her D levels at 150 ng/l on a regular basis. This seems a little high.

  2. Terry 30 October 2009 at 1:41 pm #

    Oops, I meant 150 ng/mL!

  3. Rebecca 30 October 2009 at 1:57 pm #

    I am concerned that as a nation we are become obsessed with the use of sun-cream to the extent that we are missing out on the best source of natural vitamin D. I am certainly not suggesting that we allow our skin to burn, or not use sun cream when on holiday or for the few weeks of the British summer when it is actually hot, but gently exposure to the sun is still the best way to obtain vitamin D. For example my children are advised to put on sun cream and wear a sun hat at school for the whole of the summer term (which starts at the end of April) in my opinion this is being over protective. We run the risk of seeing higher incidences of osteoporosis in years to come (vitamin D being necessary for calcium absorption) especially when linked with the increased use of cola beverages.
    (Colas, but not other carbonated beverages, are associated with low bone mineral density in older women: The Framingham Osteoporosis Study).

  4. Christine 30 October 2009 at 6:51 pm #

    Dr Briffa, thank you for your invaluable e-mails- particularly on the importance of Vitamin D to health.
    I am passing on info to a friend who doesn’t have a computer and she has a question for you.
    What is the optimum daily dose of Vit D for a 60 year old woman on HRT (Evorel 75 patches) and are there any contra-indications ?

  5. Ted Hutchinson 30 October 2009 at 7:12 pm #

    The 25(OH)D levels of the highest quintile in this study ranged from 62.0nmol/l ~ 180.0 nmol/l 22.4ng/ml ~ 72ng/ml

    In order to understand why I think including people in the upper quintile who were still vitamin d insufficient may not be giving us as complete an understanding as desirable perhaps readers new to the subject listen to Heaney’s
    You Tube Video What’s a Vitamin d deficiency

    I’d be interested to know if a status over 100nmol/l throughout the year is linked with even lower CVD incidence.

    The trouble with a study like this, that used just one one 25(OH)D reading, in a country with large seasonal variation range, is that there may be periods of greater vulnerability as immune function adjusts to rapid changes in vitamin d availability.

    This study found that an additional 3320iu/daily Vitamin D3 raised status of overweight Germans to 85nmol/l which, while higher than some of those in the highest quintile above, is still too low IMO for safety, as our basic daily need for vitamin d is only met in full, when status is kept around 100nmol/l 40ng/ml.

    At latitude 32, where an even status through the year is much easier to maintain than at latitude 52, Vitamin D Researcher Dr. Bruce Hollis says “I’m telling every pregnant mother I see to take 4,000 IUs and every nursing mother to take 6,400 IUs of vitamin D a day.

    I think it is medical malpractice for obstetricians not to know what the vitamin D level of their patients is. This study will put them on notice.”

    As the vitamin d status that permits the flow of vitamin d3 in human breast milk is also associated with lowest risk of heart attack it seems it won’t be long before medical malpractice claims are being made against cardiologists who fail to measure, let alone correct, Vitamin d insufficiency.

  6. John Adler 1 November 2009 at 3:34 am #

    How does one get one’s vitamin D Level checked, and can it be done on the NHS?

  7. Norma 1 November 2009 at 5:06 pm #

    Thanks for this – I don’t know how the earlier posts on this passed my by. My rheumatoid arthritis as now been re-diagnosed as psoriatic arthritis (or both) so I’ve been particularly interested to read about vitamin D3 in relation to these diseases. I am sending off for the grassroots test and I have found a few suppliers to provide gel capsules of D3 in this country.

    I’m keen on low – carb and high fat, originally because of hypoglaecemia but I am struck how much one has to put oneself out on a limb in order to get oneself sorted out. I like my GP and I am proud of (and need) the NHS. It gets harder as I get older, too. I really don’t have tbe brains for all this chemistry!

    Thanks again

  8. john 2 November 2009 at 4:04 am #

    Did Dr Briffa mean this, or would he care to rephrase it?

    “Vitamin D, in turn, has been found to be association[sic] with a very wide variety of disease processes including cancer, diabetes, and multiple sclerosis.”

    Vitamin D deficiency?

  9. Susan Wallace 2 November 2009 at 1:20 pm #

    Has anyone looked at this site?

    http://nadir.nilu.no/~olaeng/fastrt/VitD-ez_quartMED.html

    It calculates the UV exposure levels you need for healthy Vitamin D status, according to the time of year and weather and where you live and your skin type. It’s amazing how much time you should spend outdoors in December in the UK!!!

  10. Ted Hutchinson 2 November 2009 at 11:01 pm #

    @ John Adler “How does one get one’s vitamin D Level checked, and can it be done on the NHS?”

    Cheapest easiest source
    Grassrootshealth D Action postal 25(OH)D test $40 £24
    It can be done on the NHS but many doctors are not enthusiastic and may be reluctant to order a 25(OH)D test for someone who appears healthy. The type of test used by most health authorities is a lot more expensive than the version Grassrootshealth use although the results of their test are compatible with my local path lab.

    Bear in mind average UK adult status is around 50nmol/l, optimum is around 125nmol/l, most people require roughly 5000iu/daily to get and stay above 125nmol/l.and 10,000iu/daily is a sufficiently safe upper limit to also permit full body sun exposure in addition without any danger of toxicity. The usual recommendation is to supplement at an effective amount for 2~3 months and then get a 25(OH)D test to check the amount you have been taking is indeed adequate.

  11. Ted Hutchinson 5 November 2009 at 11:57 am #

    @Susan Wallace
    The calculator only estimates exposure required for just 1000iu.

    Naturally full body sun exposure creates 10,000~20,000iu daily Our body uses around 5000iu/daily normally.
    When breastfeeding 6400iu daily are required.
    People with inflammatory conditions my need twice as much, up to 10,000iu/daily, to keep up a safe level.

    So either expose more skin (ideally near full body) or spend 5 times as long outdoors. Be careful never to burn.

    Just a quarter of the time it takes before your skin goes pink is adequate. The process is self limiting, further UVB on newly created but unabsorbed D3 converts it to suprasterols the body doesn’t use.

    Stephan WholeHealthSource has an interesting blog on skin cancer and omega 3~6 ratio.
    Effective amounts of omega 3 improve skin’s natural photoprotection but it takes time (>3 months) to change tissue levels of omega 3 so the sooner you start the better.

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