Among those not given B vitamins 32% had died, compared to only 4% of those given high doses vitamins. This means that those on placebo were 8 times more likely to die than those on B vitamins. Homocysteine is now a proven marker for cardiovascular disease risk. For example, a recent meta-analysis concludes “each increase of 5 μmol/L in homocysteine levels increases the risk of CHD events by approximately 20%, independently of traditional CHD risk factors“. Lowering homocysteine levels with B vitamins has also been shown to reduce stroke risk.
However, early studies giving people B vitamins in the hope of reducing heart disease risk have not proven particularly effective. A recent Cochrane review of eight studies concludes ‘homocysteine-lowering interventions do not prevent cardiovascular events’ although it did report a small reduction in stroke risk. A lay person would probably assume that the people studied, 24,210 in all, had high homocysteine levels to start with and that they were given a cocktail of the known B vitamins that most effectively lower homocysteine. This, however, was not the case.
A high homocysteine level is usually defined as above 15µmol/l, however none of these study populations had averages above this. Two of the eight studies didn’t even report homocysteine levels. Those that did ranged between scores of 11.2 and 13.4 which are not very high - The average person in Britain is probably between 9 and 12. That’s a bit like given statins to people without high cholesterol levels. It’s not surprising not much happened. The same is true with statins.
Some people, however, have homocysteine levels from 15 to over a 100. These are the people who are likely to benefit most from homocysteine lowering B vitamins. That’s what the research shows.
The next critical question is were the vitamins given effective in lowering these only moderately raised homocysteine levels? Three studies didn’t even report follow up tests, so we are left with five studies. Here are their mean starting and ending homocysteine levels:
(Chaos) 11.2 – 9.7 13% drop (Hope) 12.2 – 9.7 20% drop (Norvit) 13.4 – 11.2 16% drop (Visp) 12.1 – 9.8 19% drop (Wafacs) 13.1 – 9.5 27% drop Average 12.4 -10.0 20% drop
So, the average starting point is 12.4, which is not very high, and ending point is 10.0, which is not very different – a 20% drop from what one might describe as moderately elevated to slightly elevated. When I have patients with homocysteine levels above 15 I expect to bring them down by at least 50% within three months.
But why were the interventions in these studies rather ineffective in lowering homocysteine, and lowering risk? The nutrients that do effectively lower homocysteine are vitamin B6, folic acid, B12, and also zinc with TMG in the right doses. The least effective drop was achieved in the CHAOS study which only gave folic acid. The two most effective (Norvit and Wafacs) gave the most vitamin B12 (1,000mcg). None gave zinc and TMG.
Of course, another factor is that most of the people in these trials were also on a plethora of cardiovascular drugs and it is possible that this interfered with the ability of B vitamins to have a protective effect.
What we do now know is that it is sensible to measure homocysteine since high levels clearly indicate risk. This should be a standard screening procedure but, in the UK, it is not. You can measure you own using a home-test kit.
Given the assumption that lowering a high levels would reduce risk should we all be taking B vitamins? Yes – if your homocysteine is above 15µmol/l and you have cardiovascular disease.
As far as reducing heart disease risk if you don’t have it we don’t really know. Studies on healthy people for the purposes of prevention haven’t been published. However, it certainly makes sense to both take supplements and follow a homocysteine-lowering lifestyle to ensure your level is certainly below 10, and ideally below 7. The average level of homocysteine in those who take many supplements a day has been reported as 6.1µmol/l compared to 9.6µmol/l in those who don’t.
This means eating more greens and beans, drinking less coffee and alcohol in moderation, not smoking and eating fish, a good source of B12. As far as supplements are concerned the most effective for lowering homocysteine appears to be folic acid (500-1,000mcg), B12 (500-1,000mcg), B6 (20-50mg), zinc (10 to 20mg) and TMG (500 to 2,000mg). These can be found in combination formulas.
If you’d like to know more about homocysteine, how to lower it and why it’s an important health marker, read The H Factor.