Cholesterol is a good example of how increased study gives better insight. When it became possible to study the different fractions that make up the total cholesterol, we became aware that there was a wide range of cholesterol levels found in the general population. While a person may have a normal HDL and LDL (two of the major cholesterol fractions), it is advantageous from the perspective of cardiac health to have a higher HDL and a lower LDL. In other words, there is a benefit to being better than normal.

 

When it comes to vitamins, we do not know as much as we would like to about ideal levels. During the last four to five years, our understanding has changed enormously for vitamin D; for example, “normal” intakes of vitamin D were calculated from the viewpoint of the prevention of rickets. Children living in areas where winter days are short and sunlight is limited do not get enough vitamin D from the sunshine working through their skin. This resulted in many youngsters getting rickets. Rickets is caused by a metabolic disturbance at the growing points of the bone, and consequently these children often had bowlegs from the soft bones bending outward under the child’s weight. It was found that 100 IU of vitamin D would cure rickets. Consequently, the recommended dose was 400 IU daily, and this was accepted as being the correct dose—until recently.

 

Newer actions for vitamin D have now been discovered. Vitamin D not only helps bones but improves muscle power and calcium absorption. It also seems to improve resistance to cancer. Current recommendations now call for 1,000 IU of vitamin D per day.

 

When we discuss vitamin B12 levels, we do not have as much data as we do for vitamin D. Nevertheless, vitamin B12 has some very important functions. It is necessary for cellular division and plays an important role in blood formation. A deficiency in B12 will cause large red cells with deficient hemoglobin to appear, which is called macrocytic anemia. While this is serious, far more devastating is the nerve damage that occurs to nerves of the spinal column, which can result in paralysis. This, however, is an extreme situation.

 

Recently, researchers at the University of Oxford in the United Kingdom were studying brain atrophy, or shrinkage of the brain. They found that more brain shrinkage occurred 
in the group whose vitamin B12 levels were in the “low-normal” range than in the higher levels. Of course, this does not prove that a lack of vitamin B12 is the cause. Perhaps people with lower B12 levels are missing other elements in their diet, or eating something that could be toxic.

 

We obviously need to be aware of many possible explanations for the increased risk of brain shrinkage in the group with lower vitamin B12 levels. It does seem wise, though—especially for vegetarians, who are at risk of low vitamin B12—to take some supplemental B12 from time to time.

 

Your doctor’s advice is not, in our opinion, out of line, and could help prevent a borderline deficiency.