Posted
Sunday, January 24, 2010
The study involved over half a million participants of the European Prospective Investigation into Cancer Study (EPIC), and during the study 1,248 people were diagnosed with colorectal cancer. Those in the top fifth of blood levels of vitamin D had a 40% reduced risk.
This adds to a growing body of evidence that people living in the Northern hemisphere 
have an increased risk of a number of cancer, plus weakened immune systems possibly resulting in more winter-related infections. Indeed a meta-analysis of trials, published in the American Journal of Preventive Medicine also reported that higher blood levels of vitamin D were associated with a lower risk of colon cancer.
While there is a need for well designed studies giving people vitamin D supplements versus placebos, given that cancer is a long time coming and definite results may be a decade away, there is certainly a good logical basis for making sure you are in that top fifth of vitamin D status. The blood level that correlated with this lower risk was a level above 100 nmol/l.
To achieve this kind of level means a daily intake of vitamin D of at least 1000ius or 25mcg a day, assuming you have some basic sun exposure. That’s 25mcg a day. Most multis only give 5mcg a day. Mine (BioCare’s Optimum Nutrition Formula) is somewhat better, giving 15mcg a day but even this might not be enough in winter, depending on your diet and sun exposure.
A serving of mackerel gives you are 350iu (9mcg) so, on those days you eat a serving or oily fish you are in the right ballpark. But if you don’t eat oily fish you are likely to fal short. It does also emphasize the need for sun exposure during the winter. Other options are a winter holiday, to boost your vitamin D stores, ideally eating lots of fish, or occasional use of a sun bed, or additional vitamin D supplementation of about 10mcg a day, on top of a multivitamin providing 15mcg.
If you’d like to learn more about vitamin D, which is also good for your bones and your brain, helping to cheer you up in the winter, read my Special Report – Vitamin D – Why You Are Almost Certainly Not Getting Enough.
A recent report says there is evidence that taking levels of vit C higher than 1mg a day causes blood vessels to clog up. Should we be concerned over this report? I take up to 2g a day.
Posted by SuzieB on 02/14 at 06:02 PM
I am not aware of any recent report saying this. There was a piece of research that showed that vitamin C thickens the arterial wall, which means it is stronger and thus healthier, but didn’t thin the arterial diameter. This research was wrongly picked up by the media as implying greater risk for coronary artery disease when, in fact, it implied the opposite. let me know if I’m missing something. If so, please send the full reference.
Posted by patrick on 02/15 at 03:05 PM
I am concerned that I may be taking too much vitamin D3. I take 1000iu per day. I have osteoporosis in my spine and osteopenia in my hips. I am trying to take all the supplements that may help with my condition and am also eating oily fish at least once a week.
Posted by Valerie Brooke on 02/18 at 01:07 PM
If you live in the UK,or anywhere above or below 40degrees North or South, which means all of Europe bar the tip of Spain and Italy, you won’t get enough from sunlight all year round and will benefit from supplementation except during the summer months.
You need to supplement an absolute minimum of 12.5mcg (500iu) to guarantee a blood level of about 100nmol/l and probably more like 15mcg (600iu) to guarantee an ideal blood level above 125nmol/l). That’s what I take on a daily basis in my multivitamin supplement. That assumes you are getting a certain amount from your diet, plus sun exposure.We probably need more like 30mcg to 50mcg a day from all sources.
If you eat oily fish three times a week (a serving of salmon or mackerel provides around 9mcg/350iu), eating six free-range eggs a week (two eggs provide 1mcg/40iu), exposing your skin to the sun every day (you’ll make around 10mg/ 400iu with 20 minutes exposure between 10 and 2pm in the summer), and supplement at least 15mcg/600iu daily, that will give you around 30mcg/1200iu a day. During the winter months (November to April in the UK) it’s probably worth supplementing an additional 1,000iu (25mcg) and possibly more,as you are doing, especially if you are older, have low bone mass or are prone to seasonal low moods.
Also, check your homocysteine and B12 status. B12 stimulates new bone formation and if you are low your homocysteine level is likely to be high. (See the November ‘09 newsletter for more on this). Hope this helps.
Posted by patrick on 02/18 at 01:36 PM
