Micronutrients such as vitamins and minerals are essential for biological reactions, acting on the aging process. In developed countries, the classic syndromes of vitamin deficiency such as scurvy, beriberi and pellagra, are now rare but specific subgroups of populations that are at risk of vitamin insufficiency. This is the case of the elderly, who often suffer from vitamin D deficiency and water soluble vitamins. Research over the last decade has suggested that subtle deficiencies of B12 vitamins are risk factors for vascular disease, dementia, depression, and malignancies. In this review the authors report the latest findings on bioavailability of B12 vitamins in the elderly and the association between the deficiency of these vitamins and chronic diseases.
Intake, bioavailability and B vitamin status in the elderly
Most of these vitamins are widely distributed in foods, even at relatively low concentrations (B1), While others are only provided by certain categories of food (B12.) The synthetic forms of vitamins are also used in food fortification (folic acid) and supplements (cobalamin). Bioavailability is defined as the ratio of micronutrients absorbed and stored in tissues or used. Due to functional inadequacies, the vitamin status in the elderly may be subject to greater variability than the young.
The determinants of vitamin B12 deficiency in the elderly include: environment (hospitalization, residence in a nursing home, live alone), sex (higher prevalence in men), lifestyle (smoking, sedentary lifestyle, alcoholism), vegetarian and genetic variations. The lower caloric intake due to increased mortality combined with drug therapy increases the risk of vitamin B12 deficiency in the elderly. The evidence indicates that intake of vitamins B1, B2 and B6 in this population is below recommended levels.
In one study, the concentration decreased erythrocyte thiamine pyrophosphate in the course of 3 years; this fact would be related mainly to aging. The prevalence of riboflavin deficiency ranges between 16% and 45% in most communities evaluated. Several experiences have demonstrated the high prevalence of vitamin B6 (13% to 45%). Assessments of the levels of folate have provided varied experiences as detected deficiency or risk of osteoporosis, while others did not establish this possibility. Hypochlorhydria alters the dissociation of vitamin B12 food complexes and, therefore, their release into the lumen of small intestine. Atrophic gastritis associated with pernicious b12 deficiency anemia, with poor absorption of vitamin B12. These conditions explain the altered levels of this vitamin in some elderly, although they meet nutritional recommendations.
Vitamin B deficiency and degenerative diseases
The failure of folate, cobalamin, vitamin B6, B2 and B1 and is recognized as a risk factor for chronic diseases, cognitive and neuropsychiatric dysfunction and certain types of cancer. You can also exacerbate existing conditions in the elderly. The metabolism of homocysteine requires folate, cobalamin, vitamin B6 and riboflavin. The prevalence of hyperhomocysteinemia (HHC) increases with age.
In one study, the prevalence of HHC amounted to 29.3% in subjects between 67 and 96 years. Low levels of folate play an essential role in the pathogenesis of HHC. A meta-analysis of randomized trials found that folate supplementation (0.5 to 5 mg / d) HHC can reduce by 25%, while the addition of vitamin B12 (0.5 mg / d) may decrease by 7% more. However, these predictions would not be valid in the elderly often with homocysteine levels exceeding the range of 10 to 15 mmol / l. There is also a possible moderate association between HHC and cardiovascular disease. Some studies suggest that vitamin B6 could provide independent protection against cardiovascular mortality.
The low intake or mild deficiency of vitamin B could be associated with neuropsychological impairment in the elderly. Some studies have suggested that low levels of free thiamine in the cerebrospinal fluid may be associated with risk of Parkinson’s disease, having detected a relationship between levels of vitamin B1 in plasma and cerebral cortex, with cognitive impairment in patients with Alzheimer’s disease.
HHC dependent on low levels of folate, vitamin B6 and vitamin B12 could be a risk factor for cognitive disorders, depression, dementia, Parkinson’s disease and Alzheimer’s disease. Folate deficiency also would be associated with increased risk of cerebrovascular events in the elderly. The HHC would be an independent risk factor for stroke and cognitive impairment.
Vitamin B12 deficiency may cause neuropsychiatric abnormalities such as depression test, which was not seen with folate deficiency, which indicates the specific effects of cobalamin. The HHC would be an independent risk factor for stroke and cognitive impairment in elderly is not known if it precedes the onset of dementia, or is the result of dementia associated with vitamin deficiencies.
Some studies suggest that under certain circumstances, such as high fat intake or smoking, folate deficiency may influence cell differentiation in the pancreas and contribute to the pathogenesis of pancreatitis and carcinoma. The low intake of folate, vitamin B6, Or both, would be associated with increased incidence of colorectal adenoma. It is also reported an inverse association between folate intake and colorectal and lung cancer. Moreover, the risk of breast cancer is associated with low levels of folate and possibly vitamin B6.
Mechanisms of the effects of vitamin B deficiency associated with aging
Chronic deficiencies of vitamins B can disrupt the metabolism of homocysteine. Folate deficiency can affect the configuration and structural stability of DNA, chromosomal commitment. Aging, marginal deficiencies of folate or vitamin B12 and the elevation of homocysteine are accompanied by spontaneous chromosome damage. Several studies have shown that chromosome damage can be minimized with concentrations of folate in RBCs greater than 700 nmol / l.
B vitamins may provide protection against oxidative stress by lowering homocysteine prooxidant and acting as an antioxidant. Moreover, several factors associated with brain aging (vessel disease, brain dysfunction, impaired nitric oxide activity, oxidative damage of neurons and altered methylation reactions) are related to the HHC due to folate deficiency. Also, there would be a relationship between increased homocysteine and a toxic product of lipid peroxidation in the brain of patients with Alzheimer’s disease.
Prevention of vitamin B12 deficiency in aging
Cereals, vegetables, legumes, fruits, meat, fish and dairy products contribute to the consumption of vitamin B in the populations of developed countries. In order to prevent chronic diseases, experts from Western countries recommend a daily intake of at least 5 foods that correspond to fruits or vegetables. However, low percentage of subjects who follow this recommendation. Since the grain fortification with folic acid there were increases in plasma folate indicators in various populations.
Folate intake through supplements offers additional benefits for the elderly who consume fortified foods. However, supplementation and fortification with folic acid can enhance the growth and progression of colonic lesions and decrease the effectiveness of drugs used by the elderly. It was suggested that increased folate may precipitate or worsen the neurological dysfunction in subjects with vitamin B12.
The authors estimate difficult to answer if the elderly have specific needs of certain B vitamins Information from women between 60 and 85 years suggests a need to recommend a higher daily intake of folate, however, little specific advice. Despite some quantitative differences, the recommendations made in different countries generally agree on the specific requirements of B vitamins for the elderly. The daily requirement of vitamins B would be similar (folate, vitamins B1, B2, B12) Or higher (vitamin B6) To young adults. In the U.S. recommended the use of supplements or foods fortified with vitamin B12 for over 50 years. In thiamine-deficient elderly, administration of high doses of vitamin improved welfare indexes.
Treatment with vitamin B6, Cobalamin and folate, and multivitamin intake increased levels of vitamin and reduced homocysteine. In the elderly with vitamin B deficiency2 and B6 supplementation with physiological doses of riboflavin improved biochemical markers. It has not yet succeeded in establishing the amount of folate required to increase deposits to levels protective against chronic diseases. Several ongoing studies will enable to know the effects of supplementation with folic acid and other B vitamins in the production of chronic diseases. Currently, dietary modification towards a balanced system, rich in fruits and vegetables, it is preferable to consumption of products enriched or multivitamins.
The deficiency of B vitamins in the elderly population is associated with increased risk of degenerative entities, such as vascular disease, cognitive dysfunction and neurological tumors. However, there are differences between the information currently available. Therefore, longitudinal studies are needed to demonstrate that deficiency of these vitamins or alteration of biochemical indices (HCY) produces these pathologies. Other research projects will determine whether early initiation of adequate food has protective effect against degenerative diseases and whether the elderly require special attention on the status of the B vitamins.