“For people worried about dementia our advice is you don't need to spend time and money on expensive supplements or products, like online tests,” says Which? However, they ignore the simple fact that Alzheimer’s dementia, the most common kind, is preventable, but not reversible. That means prevention is key. And to prevent something you have to a) identify those at risk as early as possible and b) take prevention steps.
They recommend to ‘eat a healthy, balanced diet .. regular physical, mental and social activity .. quitting smoking and avoiding drinking high levels of alcohol’. Of these, currently, only increasing regular physical activity has good evidence for a significant positive effect. See the chart below courtesy of Food for the Brain's thorough research.
|Risk Factor||Prevalence (%)||% of AD attributed to risk factor (PAR%)||Ease of changing||Evidence for effect|
|High homocysteine level, lowered by B vitamins||30||22%||Yes||Strong|
|Low fish & omega-3 intake||49||22%||Yes||Moderate|
|Low physical activity||34||22%||Moderate||Moderate|
|Low intake of polyphenol rich foods||75||up to 20%||Yes||Weak|
|Diabetes and pre-diabetes||5||2%||Moderate||Weak|
|Low educational attainment||24||12%||Difficult, long-term||Weak|
The top two evidence-based things you can do is to lower homocysteine by supplementing B vitamins and increase omega-3 fat intake.
However, to be fair, Which? do highlight a number of supplements that have far too low levels of B vitamins, especially vitamin B12, to be effective.
The need for B12 increases with age
The required intake of B12 goes up substantially with age for many people due to malabsorption, made worse by prescription drugs, especially antacids. As a consequence, half those over 65 have raised blood levels of homocysteine and are highly likely to benefit from supplementing high dose B vitamins in terms of dementia risk prevention. (See the summarised science for yourself here.) While the evidence for B vitamins is strongest in those with mild cognitive impairment, saying that no-one else needs supplement them is like saying sugar is only dangerous if you have diabetes.
The idea that you either have high blood homocysteine, and need extra B vitamins, or you don’t is far too black and white. In reality people’s ability to absorb vitamin B12 declines year on year with age and, eventually, many cross the magic threshold for homocysteine of 10 or 11mcmol/l, after which the evidence of a benefit from supplementing B vitamins becomes increasingly substantial, especially in those with early signs of cognitive decline. So, what to do if your level is 10, 9, 8mcmol/l? The sensible answer is to keep your B vitamin levels high.
How do you test for homocysteine and cognitive decline?
But how do you know if your homocysteine level is high? Without national screening for homocysteine, as is being done for cholesterol, you don’t. And how do you know if you have early signs of cognitive decline? You don't unless you take a test like Food for the Brain’s FREE Cognitive Function Test. If you score poorly you get a letter to take to your GP recommending they test your blood homocysteine level, which determines whether you need extra B vitamins. Far from ‘preying on people’s fears’ as Which? say, many people are relieved to find their cognitive function is good. Those whose isn’t have positive steps to take.
The cautious position, if you don’t know your homocysteine level and are 50+, is to supplement 10mcg of B12, 200mcg of folic acid, 10mg of B6, plus omega-3 fats. Two in five people over 65 in the UK have been shown to have insufficient B12 to prevent accelerated brain shrinkage. Even if only half, or even a quarter, might benefit (which is neither proven nor disproven at this time) a 1 in 4 benefit is highly effective in terms of prevention strategy.
To give you an analogy, many world governments enforce everyone to supplement folic acid to help prevent neural tube defects, by mandatory fortification of food. For every million people increasing folic acid an estimated 1 or 2 pregnancies with neural tube defect babies can be prevented. That’s a 1 in 500,000 benefit.
Why you also need omega-3 fats
Why not just get it from food? A study in Oxford found one third of those with pre-dementia had insufficient omega-3 fats for B vitamins to work. (You need BOTH these nutrients to prevent brain shrinkage and memory loss). You probably could get enough omega-3 by eating oily fish at least three times a week. We don't yet know definitively how much is optimal and it’s likely to go up with age. Omega-3 supplementation is cheaper and has been shown to protect ageing brains and minds. I do both for maximum protection.
B vitamins, especially B12, is another story. So many older people don't absorb it adequately to get enough from food. Even if you’ve tested your homocysteine level and it’s OK, I still recommend supplementing 10mcg a day, which is five times the ridiculously low RDA. That’s what I do. However, for those with raised homocysteine, even this is not enough. Studies show that levels of 500mcg, more than a hundred times what you could eat, are needed to lower homocysteine adequately to prevent brain shrinkage.
Which? knew all this because they interviewed Professor David Smith, but ignored it because they know they can get much needed publicity to increase their magazine subscriptions by a sensational headline, slamming supplements. It’s a cheap journalistic trick, but neither good science nor good advice.
PS. Here’s what Professor David Smith told them in an interview.
Which? Question: There is no convincing evidence that lowering it (homocysteine) improves the risk.
Prof Smith replies: There is now strong evidence from two trials that lowering homocysteine by B vitamin supplementation can slow cognitive decline and that the basis for this action is due to the B vitamins slowing the rate of shrinkage of key regions of the brain involved in cognition. Two key references are:
• Durga, J., M. P. van Boxtel, E. G. Schouten, F. J. Kok, J. Jolles, M. B. Katan and P. Verhoef (2007). "Effect of 3-year folic acid supplementation on cognitive function in older adults in the FACIT trial: a randomised, double blind, controlled trial." Lancet 369(9557): 208-216.
• Douaud, G., H. Refsum, C. A. de Jager, R. Jacoby, T. E. Nichols, S. M. Smith and A. D. Smith (2013). "Preventing Alzheimer's disease-related gray matter atrophy by B-vitamin treatment." Proc Natl Acad Sci U S A 110(23): 9523-9528.
In the paper by Douaud et al. on the VITACOG trial a causal pathway was shown, by Bayesian network analysis, as follows:
B vitamin supplements (especially B12) lower plasma homocysteine, which causes slowing of regional brain atrophy, which leads to slowing of cognitive decline.
A review in press in Annual Reviews of Nutrition by Smith and Refsum summarises the extensive evidence that raised homocysteine is one of the causes of cognitive decline and dementia and also reviews the intervention trials. A proof can be made available to Which? if requested.
Which? Question – Why does UK National Screening Committee not recommend dementia screening?
Prof replies: Dementia screening was not recommended mainly because there were, until the most recent B vitamin trial (VITACOG), no treatments that could be recommended that would help in people with Mild Cognitive Impairment (MCI). This decision needs to be reviewed in the light of the evidence mentioned above. It should be noted that in Swedish memory clinics screening for homocysteine is common and that patients with high homocysteine are offered B vitamins (Lökk, J. (2013). "B-vitaminer kan prövas vid kognitiv svikt." Lakartidningen 110: 1528).
We do not agree that MCI has poor predictive value for the subsequent development of dementia: in a population study, 42.5% had developed dementia by 5 years after MCI diagnosis (Roberts, et al. Neurology 82: 317-325).
However, we must stress that the Cognitive Function Test was not designed to give a diagnosis, as clearly stated on the web page:
“Please be aware that this test will not diagnose Mild Cognitive Impairment, Dementia, or Alzheimer’s disease – that is the job of your doctor or primary care provider.”
The Cognitive Function Test is simply an aid to assess cognitive abilities. Raised homocysteine can occur in spite of a healthy diet, e.g. by poor life-style and in elderly by malabsorption of vitamins like B12. Taking B vitamins can slow brain shrinkage and cognitive decline in those with raised homocysteine.