'Low homocysteine levels can increase risk of dementia'

A research team at Seoul National University Bundang Hospital has proved that the risk of dementia can increase when the blood concentration of homocysteine is low.

A research team at Seoul National University Bundang Hospital, led by Professors Bae Jong-bin (left) and Kim Ki-woong, has proved that low homocysteine levels can increase the risk of dementia similar to that of high homocysteine levels.

Homocysteine, an amino acid, promotes the accumulation of beta-amyloid, a dementia factor. When the level of homocysteine increases, it can also increase dementia and Alzheimer's disease.

As medical professionals have recently acknowledged the dangers of homocysteine, interest in vitamins that can control it is also increasing after researchers found that taking vitamins can reduce homocysteine in the body and lower the risk of dementia, according to the hospital.

"However, depending on this information, if patients misuse vitamins without consulting a specialist, or take additional vitamins even though they consume enough vitamins through vegetables or fruits, unexpected side effects may appear," the hospital said. "Excessive intake of vitamin supplements can cause hyperhomocysteinemia, a symptom in which homocysteine levels fall below the appropriate level."

The team has found that this can increase the risk of dementia as much as high homocysteine levels, the hospital added.

The team, led by Professors Bae Jong-bin and Kim Ki-woong of the Department of Mental Health, tracked 2,655 Koreans aged 60 and more from 2010 to 2018.

As a result of the relative evaluation by classifying groups according to homocysteine levels, the low homocysteine group (≤8.9 mmol/L) had a maximum 4.3 times risk of Alzheimer's disease compared to the normal group (9.0-10.5 mmol/L), similar to the risk of the group with high homocysteine levels (up to 4.9 times compared to the normal group).

"It is also noteworthy that hyperhomocysteinemia is associated with high vitamin intake," the team said. "The vitamin intake rate of the low homocysteine group reached 41.2 percent, which was significantly higher than that of the entire study subjects (28.4 percent)."

Researchers also confirmed that the homocysteine level decreased as the body concentration of folic acid, a vitamin B group, and vitamin B12 increased.

These results suggest that adequate intake of vitamin B-containing vitamins helps physical health and dementia prevention, but exceeding the appropriate level may increase the risk of dementia due to hyperhomocysteinemia.

The researchers also stressed that the study is significant as the first in the world to identify the association between hyperhomocysteinemia and the risk of dementia and Alzheimer's disease.

While most recent studies have focused on the problems of high homocysteine levels, the team expects that the study will be an important turning point in preparing guidelines for dementia prevention and treatment.

"Compared to foreigners, Koreans have a higher intake of vitamins through vegetable foods such as kimchi, so they should be more careful about hyperhomocysteinemia," Professor Bae said. "Vitamin supplements are effective when the intake of vegetables and fruits is small due to the usual meat-based diet. However, if patients are already getting enough through their diet, too much vitamin can adversely affect the body."

Professor Kim also said, "There are various academic reports that hyperhomocysteinemia affects not only dementia but also peripheral nerve damage."

Accordingly, if the intake of vitamins is properly managed, not excessive or deficient, it will help prevent dementia and neurological diseases, Kim added.

The results of the research were published in Clinical Nutrition.