维生素B 可以减缓脑萎缩

Vitamin slows brain shrinkage
by 50 percent 
Brain atrophy -- or brain shrinkage -- is very common in adults over the age of 60. It occurs when neurons in your brain die or lose their connection to other neurons. The average brain shrinks at a rate of .5 percent a year once you hit 60. And some of this "shrinkage" explains why you may not feel as sharp as you did when you were 20.
For some, brain atrophy occurs at an accelerated pace. We call this "mild cognitive impairment" and it describes they type of memory loss that goes beyond the "normal" aging brain. People with this kind of mild cognitive impairment lose brain mass at a rate of 1 percent a year. And those with Alzheimer's disease experience a loss rate of 2.5 percent per year.
For many decades, nutritionists have talked about one factor that plays a role in how quickly your brain shrinks: Your homocysteine level.
Homocysteine is an amino acid implicated for its role in many different diseases, especially heart disease. It's also a major risk factor in whether or not you develop dementia and Alzheimer's. Basically, the more homocysteine in your blood, the higher your risk of experiencing serious cognitive decline.
But, here's the good news...

One vitamin significantly lowers your homocysteine levels

It's well-documented that members of the vitamin B-complex family can significantly lower homocysteine levels. In fact, recent studies show that taking vitamin B every day can lower your homocysteine by 25 to 50 percent.
And scientists from the University of Oxford recently took this premise one step further. Since we know that vitamin B decreases homocysteine, can we assume that it also slows brain shrinkage? And even more importantly, can it work for men and women who already show signs of memory loss?
To answer these questions, the Oxford scientists recruited 271 healthy men and women over the age of 70 with mild cognitive impairment. The participants all scored below average on tests that assessed word recall and fluency. In addition, they all expressed concern over memory loss but had not been formally diagnosed with dementia. Next, each of the participants were given MRI scans to determine the amount of atrophy in their brain.
In the next step the scientists divided the volunteers into two groups. One group took vitamin B supplements each day for two years. The tablets contained three components of the B family of vitamins: .8 mg of folic acid, .5 mg of B12, and 20 mg of B6. The other group received a placebo for two years; and to keep things honest, the participants weren't told whether they received the real vitamin or the placebo.

Vitamin B group shows major improvements

After two years, the participants got another set of MRIs and another round of blood work. The scientists then analyzed the data and here's what they found:
1. The vitamin B group lowered their homocysteine levels by an average of 23 percent.
2. Homocysteine levels of the placebo group increased by 8 percent.
3. Overall, the vitamin B group experienced 30 percent less brain shrinkage compared to the placebo group.
4. Lastly, people with the most homocysteine at the outset of the study benefitted the most. They experienced 50 percent less brain shrinkage compared to the placebo group.
According to Professor David Smith and lead scientist from the Oxford team, "We have shown that treatment for two years with B vitamins markedly slows the accelerated rate of atrophy in people with mild cognitive impairment."
He went on to say, "It's a bigger effect than anyone could have predicted and it's telling us something biological. These vitamins are doing something to the brain structure – they're protecting it, and that's very important because we need to protect the brain to prevent Alzheimer's."
Gee, I couldn't have said it better myself!

Get on the vitamin B bandwagon!

There are lots of things you can do to protect your brain against shrinkage. First off, make sure you're taking a quality multivitamin. It should contain at least 25 mg of B6.
Next, think about adding .8 mg folic acid and .5 mg B12 into your regimen.
You'll need to take them separately to get to the dosage used in the study. Folic acid is easy to find. And B12 isn't too bad either, really. You'll just need to take the sub-lingual form. This means it comes as a liquid and you use a dropper to place it under your tongue. There's also a dissolvable, under-the-tongue pill form that's popular.
And lastly, for anyone really concerned about Alzheimer's disease, I recommend looking back at my 2008 article about this preventable epidemic.
Until next time,
Allan Spreen, M.D.
NorthStar Nutritionals