'To D or not to D?' - Part 4
It is that time of year again, when we need to be thinking about keeping our body’s vitamin D levels topped-up through the winter months.
If you have been fortunate enough to spend a lot of time outside throughout the Summer months, your vitamin D levels will only recently have started to decline. However, for those individuals who have been working inside throughout the summer (or have not been able to spend much time outside for other reasons) your levels may already be diminished and at insufficient levels.
This is due to the simple fact you have not been getting bathed by the sun’s rays; our primary source of vitamin D. Although we have had some lovely, sunny days through September and October, the sun is now too low to be effective in the production of active vitamin D. Lots of you have been very aware of this and been asking me during your appointments about when to start supplementing, effective dosages and what to except.
Following the last vitamin D question and answer article, it was clear from your response that many of you are very interested in the whole topic of vitamin D and the positive effects it can have on your health. I have been sent some really interesting questions on the topic and below, I hope, are some answers that you will find informative and thought-provoking. For a ‘longer read’ I have included some links to studies and articles which expand on my answers.
Your Questions Answered
Question 1 – from David in Sparham
“I am not very good at remembering to take medications and supplements. Does it make any difference whether I take a large dose of vitamin D once a week or a smaller dose daily?”
Thank you, David, for your question as it is quite an important point-of-note regarding when to supplement.
Studies have shown (see link below) that supplementing on a daily basis is more effective than once a week. This appears to be down to a combination of more regular absorption in the gut and also a tendency towards better compliance by people when they have a daily routine. If you struggle to remember to take it every day, try keeping your vitamin D somewhere like next to the kettle if you always make a morning drink. Or perhaps next to your toothbrush in the bathroom. You could also set an alarm on your phone. Your levels are going to stay much more even if you supplement every day.
This study on the ‘Efficacy of different doses and time intervals of oral vitamin D’ makes for interesting reading on this topic.
Question 2 – from
Katie in Cromer
“What is the best time of day to take vitamin D? I have heard conflicting opinions that it helps you sleep and also that it can cause problems with sleeping!?”
Great question Katie and one that does divide opinion. I have been asked this a few times by patients and I answer it by saying that we get our vitamin D naturally when the sun’s UV light hits our skin. This tends to be from late morning to mid-afternoon during high summer. Therefore, we could surmise that we have evolved to deal with regulating vitamin D around this time of day.
So, it would seem logical to also administer it during the morning up until lunchtime. As the sun’s strength is ineffective for the production of vitamin D during the evening, we do not produce it naturally at this time of day. So, there indeed may be situations where it could interfere with sleep patterns. If you or anyone you know suddenly finds that their sleeping pattern changes after supplementing vitamin D later in the day, cease taking it for a couple of weeks to see if anything improves.
This Healthline article ‘When Is the Best Time to Take vitamin D? Morning or Night?’ shows the differences of opinion around what time of day is best to supplement. In the end, the most important thing is finding the time that works best for you.
Question 3 - from Sam in Hingham
“I have read that some types of cancer are associated with low vitamin D. But is this a case of ‘which came first? The chicken or the egg?’
Thanks for this question Sam, as it is big topic of conversation. This is definitely an area where research and evidence can best address this one, as there is no definitive evidence to say that if you do ‘X’, you can prevent ‘Y’. Nor can we say that any one thing causes any type of cancer.
However, there are multiple studies out there to read and review - and one landmark cancer study done in the USA in 2006 by the Garland brothers and Dr William Grant (see link below) showed the positive effects of taking vitamin D. There was a statistically beneficial effect on reducing the risk of developing colorectal, breast and a wide variety of other cancers by 30% to 50%. It was estimated that if you take 1000IU of vitamin D/day, you reduce your risk of developing colorectal, breast, prostate and ovarian cancer by approximately 50%.
Below are just some of the studies undertaken in recent years regarding the link between vitamin D levels and cancer.
‘The role of ultraviolet B irradiance and vitamin D in prevention of ovarian cancer.’
Question 4 –
from Natasha in Colkirk
“I have heard that low vitamin D is linked to depression. I suffer from Seasonal Affective Disorder (SAD) in winter. Could that be helped by taking Vitamin D?”
If you live at a higher latitude (as we do in the U.K.) you are probably aware of some minor changes to yourself that accompany the shortening days of late autumn and winter. As there is less light, in terms of both intensity and duration, your hibernation impulse makes you want to eat more and be less energetic. Most of us cope quite well with these changes, and indeed, some become energized by the prospect of brisk January days and winter sports.
The characteristic symptom of SAD is the onset of major depressive feelings at certain times of the year. Physical activity decreases, you feel very lethargic and even sluggish. Almost any physical activity seems to be too much effort. Typical symptoms of SAD include: -
• Depression that begins in autumn and winter
• Lack of energy
• Decreased interest in work and important activities
• Increased appetite with weight gain
• Carbohydrate and sugar cravings
• Increased need for sleep and excessive daytime sleepiness
• Social withdrawal
• Extreme afternoon slumps with decreased energy and concentration
• Decreased sex drive
Epidemiologists, best described as ‘disease detectives’, estimate that 2 to 3% of the population develop full blown SAD with another 7% suffering a less extreme form of the condition. Women are 4 times as likely to get SAD and the average age of onset is 23 years. As winter days are shorter at higher latitudes, the further you live from the equator the greater the chance you will develop SAD.
Interestingly, Natasha, a few years ago I ran an in-house study at the Practice with 20 volunteer patients who had a variety of issues related to vitamin D deficiency with 4 of the participants suffering from SAD. They were supplemented 5000UI of vitamin D3 for 6-weeks and then we reviewed the outcome. All 4 expressed a definite improvement in their symptoms and continued to supplement until Easter of that year. To this day, they still supplement as they continue to find benefit.
Another consideration is to look at using a high-intensity daylight lamp. Indoor, bright office lights emit between 500 to 700 lux whereas a high-intensity light is between 5000 to 10,000 lux. Studies carried out on people who suffered from SAD were exposed to light (either low or higher intensity though they did not which) and those suffering from SAD experienced a dramatic reduction in their symptoms. These studies continue to duplicate the same results and benefits of using a high-intensity lamp in the treatment of SAD.
Those of you who suffer from seasonal affective disorder in the winter months may be interested in a article I wrote on the subject of nutrition and possible links to SAD. Changes in diet have been shown to be helpful for this condition. To read more click HERE