A new study has caused some consternation as its findings go against current accepted wisdom that vitamin D supplements can decrease the risk of falls in older people. But all is not what it seems….
The study involved 200 Swiss men and women, living in their own homes, who had already experienced at least one fall within the previous year. All were aged at least 70 (with an average of 78 years) and were mobile enough (with or without a walking aid) to use public transport to attend clinic visits. So far, so good.
These volunteers were randomly divided into three groups who each received vitamin D supplements, for 12 months, in varying doses of either:
– 24,000 IU (600 mcg) vitamin D3 (in the form of a 5ml drink solution) taken as a single dose per month (equivalent to 800 IU (20 mcg) per day)
– 60,000 IU (1500 mcg) vitamin D3 taken a single dose once a month (equivalent to 2000 IU (50 mcg) per day) or
– 24,000 IU (600 mcg) vitamin D3 plus 300 mcg of calcifediol (a liver metabolite of vitamin D) taken as a single dose per month.
Over the course of the year, the number of falls experienced were recorded and, unexpectedly, those taking the highest doses of vitamin D were more likely to experience a fall than those taking the lowest dose (66.9% versus 47.9%).
The first thing to note is that all those taking part had previously had at least one fall, yet only 58% were classed as vitamin D deficient at the start of the study. This suggests that, in almost half of cases, the falls in this older population, were related to factors other than vitamin D status. Supplements could therefore not be expected to have any magical protective effects.
The second thing to note is the odd way of taking vitamin D3 in this study – a large single dose taken all in one go, once a month, for a year. Although vitamin D3 is fat-soluble and stored in the liver, large single doses can cause raised a calcium level (hypercalcaemia) with associated side effects such as headache and weakness that might contribute to a fall. These high doses are usually prescribed for people with severe vitamin D3 deficiency to get their levels up quickly. Most healthy people who are not severely deficient in vitamin D3 take supplements on a daily basis to maintain stable blood levels and avoid the risk of hypercalcaemia. The researchers even admit that ‘the physiology behind a possible detrimental effect of a high monthly bolus dose of vitamin D on muscle function and falls remains unclear and needs further investigation’.
Newspaper reports have suggested that vitamin D supplements might have made patients more active in this study, so they had a higher chance of falling over. This is pure speculation. In fact, the possible reasons behind the increased risk of falling in those taking the highest doses were not discussed in the study. More likely explanations are the effects of chance (200 patients divided into three groups is a relatively low number) and the confounding factors related to a frail, elderly population. To me, this study only serves to prove that taking a whole month’s worth of vitamin D3 in one single dose is best avoided.
Vitamin D and falls
At one time vitamin D was all about calcium absorption and healthy bones. Now it is recognised as having hormone effects throughout the body, including a strengthening effect on muscle. Research suggests that vitamin D3 binds to receptors in muscle cells to increase gene activity and promote protein production in certain ‘fast twitch’ muscle fibres. These muscle fibres help to maintain balance and co-ordination and rapidly respond to instability to help prevent a fall. This effect would only be improved by supplements in older people who are vitamin D deficient.
In the UK, the risk of older people being deficient in vitamin D3 is high because of our northern latitude. We can only make vitamin D3 in our skin when the UV index is greater than 3. Older people tend to have reduced sun exposure, especially if they are confined indoors, while your ability to synthesise vitamin D in the skin after the age of 60 is at least four-fold less than in your 20s. Older people also tend to have smaller appetites and eat fewer vitamin-D enriched foods, so supplements are widely recommended at a dose of at least 10 mcg (400 IU) per day for those aged 65 plus. A minimum intake of 20 mcg (800 IU) is needed to maintain vitamin D levels during winter months.
A large international analysis of data from 10 trials ,involving over 17,000 older adults age 60 plus, found that taking vitamin D supplements (200 IU – 1000 IU per day) resulted in 14% fewer falls than placebo. Those who benefitted most were community-dwelling (aged <80), who also took calcium supplements, had no history of fractures or falls, and who took a dose of at least 20 mcg (800 IU) for longer than 6 months. The conclusion was that Vitamin D treatment effectively reduces the risk of falls in older adults.
In the UK, research concluded that treating the entire UK population aged 60 plus with vitamin D supplements at a dose of 800 IU (20 mcg) daily would, over a five-year period, prevent over 430,000 minor falls, avoid 190,000 major falls, prevent 1579 acute (fall-related) deaths, avoid 84,000 person-years of long-term care and prevent 8,300 deaths associated with increased mortality from the long-term effects of experiencing a fall.
In the United States, the CDC Injury Centre has also concluded that the number of fatal falls in the older population will rise to 100,000 deaths per year by 2030, but that doctors can reduce future falls by nearly 25% through screening for falls risk, reviewing and modifying medications, and recommending Vitamin D supplementation.
Other benefits of vitamin D
Lack of vitamin D is associated with numerous deficiency symptoms including:
– Rickets, Osteomalacia, Osteoporosis
– Osteoarthritis progression
– Increased susceptibility to infections
– Diabetes (types 1 & 2)
– Arterial calcification, high blood pressure and coronary heart disease
– Cancer of the colon, rectum and breast.
In view of this, I certainly would not change my current advice about taking vitamin D based on this single study.
The EU recommended daily amount (RDA) for vitamin D is just 5 mcg (200 IU) per day, while Public Health England recommend that eeryone takes a supplement providing 10mcg vitamin D per day during winter months. Most experts believe these low levels are vitamin D are inadequate and, in the absence of exposure to sunlight, a minimum intake of 20 mcg (800 IU) to 25 mcg (1000 IU) daily is needed to maintain healthy blood levels during winter. Others argue that intakes of 40 mcg vitamin D per day are more optimal, irrespective of sun exposure.
The best way to know if you are vitamin D deficient is to have a blood test to assess your levels. Guidelines recommend that doctors perform vitamin D testing in those whose symptoms could be due to vitamin D deficiency (eg widespread muscle or bone pain). People who are in a known at-risk group (such as the elderly, pregnant women and people with darker skin pigmentation) do not need necessarily need their vitamin D levels measured before being advised to take a vitamin D supplement as the costs would be prohibitive.
Home Vitamin D Test Kits
If you want to know your vitamin D status, accurate home test kits are available which involve sending a fingerprick sample of blood to a laboratory. The results will tell you if you need a supplement, and usually suggest the dose of vitamin D3 you need.
If you decide to take a supplement, look for those that contain vitamin D3 (animal cholecalciferol) as this is 20% – 40% more effective in maintaining blood vitamin D levels than the vitamin D2 (plant ergocalciferol) form.
You can take vitamin D3 as a capsule, an oral spray, or as a cream that you rub in for absorption through the skin. Many good brands are available, and I particularly recommend the following for quality and value.
The European Food Safety Authority have suggested a tolerable upper intake level (USL) for vitamin D3 of 100 mcg per day (4000 IU) for long-term use, but higher doses of 5000 IU or more may be recommended for short-term use if you are vitamin D deficient until your vitamin D status is corrected.
Very high intakes can cause side effects such as headaches and may disrupt calcium balance to trigger kidney stones.
Have you had your vitamin D levels checked and been surprised by the result? Do you take a supplement? If so, at what dose?
Photo credits: tinpalace / freeimages