It could be old age,or it could be low B12

Her mother couldnt remember the names of close relatives or what day it was. She thought she was going to work or needed to go downtown,which she never did. And she was often agitated.

A workup at a memory clinic resulted in a diagnosis of early Alzheimers disease,and Katz was prescribed Aricept,which Atkins said seemed to make matters worse. But the clinic also tested Katzs blood level of vitamin B12. It was well below normal,and her doctor thought that could be contributing to her symptoms.

Weekly B12 injections were started. Soon afterward,she became less agitated,less confused and her memory was much better, said Atkins. I felt I had my mother back,and she feels a lot better,too.

Now 87,Katz still lives alone in Manhattan and feels well enough to refuse outside assistance.

Still,her daughter wondered,Why arent B12 levels checked routinely,particularly in older people?

It is an important question. As we age,our ability to absorb B12 from food declines,and often so does our consumption of foods rich in this vitamin. A B12 deficiency can creep up without warning and cause a host of confusing symptoms that are likely to be misdiagnosed or ascribed to ageing.

A VITAL NUTRIENT

B12 is an essential vitamin with roles throughout the body. It is needed for the development and maintenance of a healthy nervous system,the production of DNA and formation of red blood cells.

A severe B12 deficiency results in anaemia,which can be picked up by an ordinary blood test. But the less dramatic symptoms of a B12 deficiency may include muscle weakness,fatigue,shakiness,unsteady gait,incontinence,low blood pressure,depression and other mood disorders,and cognitive problems like poor memory.

Labs differ in what they consider normal,but most authorities say a deficiency occurs when B12 levels in adults fall below 250 picograms per millilitre of blood serum. Like all B vitamins,B12 is water-soluble,but the body stores extra B12 in the liver and other tissues. Even if dietary sources are inadequate for some time,a serum deficiency may not show up for years.

In its natural form,B12 is present in significant amounts only in animal foods,most prominently in liver. Good food sources include other red meats,turkey,fish and shellfish. Lesser amounts of the vitamin are present in dairy products,eggs and chicken.

THOSE AT RISK

Natural plant sources are meagre at best in B12,and the vitamin is poorly absorbed from them. Many strict vegetarians and all vegans,as well as infants they breast-feed,must consume supplements or fortified breakfast cereals to get adequate amounts.

Certain organisms,like the bacterium Spirulina and some algae,contain a pseudo-B12 that the body cannot use but may result in a false reading of a normal B12 level on a blood test. Despite claims to the contrary,laver,a seaweed,and barley grass are not reliable sources of B12.

Others at risk of developing a B12 deficiency include heavy drinkers (alcohol diminishes B12 absorption),those who have had stomach surgery for weight loss or ulcers,and people who take aminosalicylic acid (for inflammatory bowel disease or tuberculosis) or the diabetes drug metformin (sold as Glucophage and other brands).

Large doses of folic acid can mask a B12 deficiency and cause permanent neurological damage if normal levels of B12 are not maintained. Supplements of potassium impair B12 absorption in some people. JANE E BRODY