Dr. David Grimes reminds us of vitamin D

In response to the Heart Scan Blog post, Fish oil makes you happy: Psychological distress and omega-3 index, Dr. David Grimes offered the following argument.

Dr. Grimes is a physician in northwest England at the Blackburn Royal Infirmary, Lancashire. He is author of the wonderfully cheeky 2006 Lancet editorial, Are statins analogues of vitamin D?, questioning whether the benefits of statin drugs simply work by way of increased vitamin D blood levels.

There is a fashionable interest in Omega-3 fatty acids, and these become equated with fish oil.

But fish oil is much more. Plankton synthesise the related squalene (shark oil) which, in turn, is converted into 7-dehydrocholesterol (7-DHC). The sun now comes into play and it converts 7-DHC into vitamin D (a physico-chemical process).

Small fish eat plankton, large fish eat small fish, and we eat large fish. So vitamin D passes through the food chain.

This has been a vital source of vitamin D for the the Inuits and also for the Scots and other dwellers of northwest Europe. (Edinburgh is on the same latitude as Hudson Bay and Alaska, further north than anywhere in China). In these locations there is not adequate sunlight energy to guarantee synthesis of adequate amounts of vitamin D, again by the action of sunlight on 7-DHC in the skin.

When the Scots moved from coastal fishing villages to industrial cities such as Glasgow, they became seriously deficient in vitamin D, and so the emergence of rickets. This was followed by a variety of other diseases resulting from vitamin D deficiency: tuberculosis, dental decay, coronary heart disease, and even multiple sclerosis and depression (the Glasgow syndrome).

And so it was with the Inuits. When their diet changed from fish for breakfast, fish for lunch, fish for dinner, they became deficient of vitamin D and they developed diseases characteristic of industrial cities, where there is indoor work for long hours, indoor activities, and atmospheric pollution.

It is the vitamin D component of fish and fish oils that is important.

I recently saw an elderly lady from Bangladesh living in northwest England. I would have expected her to have a very low blood level of vitamin D, as her exposure to the sun was minimal. However the blood level was 47ng/ml, not 4 as expected. She eats oily fish from Bangladesh every day, showing its value as a source of vitamin D with subsequent good health. I expect her blood levels of omega-3 fatty acids would also be high.

But it is unfashionable vitamin D that is important, not fashionable omega-3.

David Grimes

Excellent point. The health effects of omega-3 and vitamin D are intimately intertwined when examining populations that consume fish.

In this study of Inuits, it is indeed impossible to dissect out how much psychological distress was due to reduced vitamin D, how much due to reduced omega-3s. My bet is that it's both. Thankfully, we also have data examining the use of pure omega-3 fatty acids in capsule (not intact fish) form, including studies like GISSI Prevenzione.

Nonetheless, Dr. Grimes reminds us that both vitamin D and omega-3 fatty acids from fish oil play crucial roles in mental health and other aspects of health, and that it's the combination that may account for the extravagant health effects previously ascribed only to omega-3s.

Comments (13) -

  • moblogs

    11/3/2009 9:29:35 AM |

    Dr. Grimes is a great man. He took a bit of time out to answer a few of my questions by email.

  • Anonymous

    11/3/2009 2:19:24 PM |

    Thank you for the great site. I have learned much from coming here. I recently purchased some vitamin D3 and krill oil. What would be the proper dose per day?
    Thank you.

  • Anne

    11/3/2009 2:45:52 PM |

    Dear Dr Davis,

    I had no idea that fish contained a lot of vitamin D, I knew they contained some but I didn't think it was a lot - maybe this explains my continuing over high 25(OH)D results  - currently 250 nmol/L (100 ng/dl). I only take 2,000 IU D3 per day but I eat lots of oily fish ! I eat a can of sardines every day and large portions of salmon and seabass several times per week. If this is why my 25(OH)D is so high that would be something important to inform my endocrinologist about.


  • Adolfo David

    11/3/2009 10:01:30 PM |

    Ummm, but vitamin D elevates HDL cholesterol and statins do not elevate HDL. This analogy is confusing for me at this point, isnt it?

    It has been great to find this blog, I support time ago Omega3 EPA DHA and Vitamin D3 supplementation and also I am LEF member time ago, in whose magazine I have read great articles by Dr Davis. Congratulations from Europe.

  • Adolfo David

    11/3/2009 10:06:39 PM |

    Thinking about that analogy, well statins could active vitamin D receptors with no increase in vitamin D in blood.

    For example, resveratrol can activate vitamin D receptors at least in cancer cells and obviously resveratrol does not increase HDL nor vitamin D (of Steroid Biochemistry and Molecular Biology, february 2003)

  • Dr. William Davis

    11/3/2009 11:39:17 PM |

    Yes, I think that trying to attribute ALL statins' effects to an increase in vitamin D is a stretch. But I believe there's credible evidence to suggest that at least some of the statin effect is due to D.

    Personally, I'd rather take vitamin D and use little or not statin.

  • Michelle

    11/4/2009 1:15:22 AM |

    Great post! This seems to be another example of what can happen when nutrients are taken/studied on their own, instead of in their original context.  I don't discount the credibility of supplements, but so often it seems whole foods are the best.

  • blogblog

    11/5/2009 12:54:21 PM |

    Had Dr Grimes spent two minutes researching the facts he would have realised his theory is highly implausible. Fish oil contains negligible Vitamin D. You would need to consume a whopping 100g of sardine oil every day to get a mere 332iu of vitamin D. http://www.nutritiondata.com/facts/fats-and-oils/633/2 (based on USDA data). However eating large quantities of fish would supplement vitamin D levels.

    Rural Scots and Inuits would have obtained ample vitamin D (up to 8000iu/day) by spending time outside during Spring-Summer-Autumn. The body stores vitamin D for 3-4 months.

    The effects of fish oil and vitamin D are almost certainly separate although some synergistic effect may be present.

  • blogblog

    11/5/2009 1:31:45 PM |

    One of my university biochemistry lecturers said to me many years ago  'nutritional epidemiology is BS because it doesn't account for genetic differences'.

    Inuits don't need high intakes of vitamin D because most of them have the bb allele of the vitamin D receptor. This mutation is also common in other Asian populations This means they use vitamin D extremely efficiently. People with the bb allele have a significantly lower incidence of rickets, osteoporosis and prostate cancer (and presumably depression and heart disease).

    Nocturnal mammals have extremely low vitamin D needs due to extremely efficient vitamin D metabolism. Fruit bats have no detectable serum vitamin D.

  • Dr. William Davis

    11/5/2009 4:06:38 PM |

    Hi, Blogblog--

    I believe Dr. Grimes is referring only to consumption of fish, not fish oil capsules.

    I wasn't aware of the VDR polymorphism in Inuits. Thanks for that insight.

  • buy jeans

    11/4/2010 5:12:42 PM |

    When the Scots moved from coastal fishing villages to industrial cities such as Glasgow, they became seriously deficient in vitamin D, and so the emergence of rickets. This was followed by a variety of other diseases resulting from vitamin D deficiency: tuberculosis, dental decay, coronary heart disease, and even multiple sclerosis and depression (the Glasgow syndrome).

  • Dr David S Grimes

    8/15/2011 9:46:35 PM |

    If you would like to know a bit more about Vitamin D, you could look at 3 three recent lectures that I gave in London in the Spring of 2011. They are available on You Tube :

    Vitamin D clinical experience

    Vitamin D and cancer

    Vitamin D and pregnancy – inheritance

    David Grimes