Experts are warning consumers against taking large doses of vitamin B3 following news that the vitamin can help combat Alzheimer's disease in mice. Claire O'Connell reports
COULD A simple vitamin be the magic bullet for Alzheimer's disease? Probably not, according to experts here.
A US study has found that a particular form of vitamin B3 could slow the progression of the disease in animals - but the vitamin is unlikely to provide a quick fix for the condition in humans, and lifestyle factors such as diet, exercise and mental stimulation remain the most important allies in protecting the brain.
The study, at the University of California, Irvine, looked at mice that had been genetically altered to develop symptoms of Alzheimer's, including a buildup of protein tangles in the brain and a loss of memory over time.
When they gave the animals a form of vitamin B3 called nicotinamide over several months, tangles in the brain appeared less severe and the mice performed better on standard memory tests.
"When tested for efficacy, our results suggest that nicotinamide is a promising, safe and readily available therapeutic for the treatment of Alzheimer's disease, as it restores cognitive decline associated with Alzheimer's disease pathology," reported the study, which was published in the Journal of Neuroscience last week.
Next year will see a trial on 70 human volunteers newly diagnosed with Alzheimer's, to see whether taking 2g per day of the vitamin affects the disease progression in people.
However, experts warn that consumers should not take high doses of vitamin B3 on the basis of evidence to date.
"This new study provides preliminary, animal-level research, and it's difficult to extrapolate to humans, particularly for psychological and mental changes," says Dr Dónal O'Mathúna, senior lecturer in ethics, decision-making and evidence at Dublin City University.
Low levels of vitamin B3 in the diet have previously been linked in humans with an increased risk of developing Alzheimer's disease, but the studies done so far are a long way off providing clinical data, he notes.
And the current Alzheimer study in the mouse model is of limited application to humans, where the condition is more complex, according to Prof Des O'Neill, a professor of gerontology at Trinity College Dublin.
The disease complexity in humans means that the basic research from animal models doesn't always translate into therapies for patients, even though the findings generate much interest.
"Everyone around Alzheimer's, including the relatives, are desperate for something to happen, and scientists want to advance themselves and that's quite appropriate," he says.
"So, between the two of them, you get a ferment over these breaking stories. Then nearly always you see the clinicians coming out and saying 'actually, it's not quite there'."
Lifestyle change is more important than concentrating on vitamin or drug-based approaches, says O'Neill.
"The most important message is that for people who are predisposed to getting Alzheimers disease, if you put them into a stimulating environment, they are less likely to get it and it will delay progression.
"It's the real old-fashioned thing of 'if you don't use it, you'll lose it' - using it protects you," he says.
"We would be saying to people, 'don't go taking lots of nicotinamide because there is some evidence that at a high dose it can cause liver damage'.
"Our worry is that people will get distracted by the vitamin supplements, going off looking for the exotic when heaven is close at hand, and the real issue is to get out there physically and mentally, stop smoking, get your blood pressure under control and eat five [portions of] fruit and veg a day. I'm afraid it's as unglamorous as that."
The healthy diet message is echoed by the Food Safety Authority of Ireland (FSAI), where the recommendation is to avoid supplementation and get vitamin B3 from food sources instead.
"Consumers can get all they need of this vitamin just by consuming a healthy diet," says Alan Reilly, deputy chief executive of the FSAI, in response to news of the Alzheimer's study.
"The current recommended daily allowance of vitamin B3 is around 18mg, so it's not huge, and we wouldn't be recommending that you take supplements. We would be firmly focusing consumers on a healthy, balanced diet."
On the Irish market, over-the-counter standalone vitamin B3 supplements typically contain no more than 100mg of the vitamin, and levels tend to be lower again in multivitamin and B-complex formulations, according to Erica Murray, spokeswoman with the Irish Association of Health Stores (IAHS).
She welcomes the new research but describes it as "limited", and says the IAHS would not encourage consumers to take high doses of vitamin B3 based on the data - although she doubts many would even consider it.
"I find our consumers are very well informed and there would hardly be anyone who would come in on foot of a laboratory experiment on mice looking for 2g of vitamin B3 for their mother or father who may be in the late stages of Alzheimer's. People are more questioning than that," she says.
"The general population need to not just jump at this and think this is going to be the solution to all their problems.
"They need to be doing the other stuff and building a healthy profile for themselves before they start thinking about adding in doses of vitamin B3."
Finding vitamin B3
Vitamin B3 occurs naturally in meat, fish, brewer's yeast, sunflower seeds and peanuts, and is involved in healthy metabolism, cardiovascular and brain function.
One form of the vitamin, niacin, may help improve cholesterol profiles in the blood but high doses can bring about an uncomfortable tingling sensation or flushing of the skin.
Another form of the vitamin, nicotinamide, has been shown to slow Alzheimer's disease in mice. This form is not associated with skin flushes, but at high supplemental levels it can be toxic to the liver.