Micronutrients for healthy aging

During the aging process, the body changes in many ways affecting its physical function. Some age-related physical changes such as wrinkles, graying hair and weight gain are obvious. Other changes, such as the gradual loss of bone tissue and the reduced resiliency of blood vessels, go unnoticed, even for decades. The rate of these processes can be very different from person to person and depend on a combination of both genetic and environmental factors.

Healthy aging involves both supporting important functions in the body and reducing the risk of age-related diseases. Several conditions that were once thought to be part of normal aging have now been shown to be due to disease processes that can be influenced by lifestyle such as tobacco smoking, physical activity and nutritional intake. Lower food intakes and changes due to aging can increase the risk of nutritional deficiencies.

Elevated concentrations of homocysteine in blood have been suggested to increase cardiovascular mortality, the incidence of stroke and the risk of chronic heart failure. Since studies have shown that increased intakes of vitamin B9 (folate / folic acid) and vitamin B6 as well as vitamin B12 are associated with lower homocysteine levels, an adequate intake of these B vitamins could reduce the risk of developing cardiovascular diseases in the long-term (5). In the case of vitamin B12, the achievement of an optimal status is particularly difficult for many older people because of the common problem of limited absorption of food-bound B12 (6).

Studies have shown that people who eat a diet rich in antioxidants have a lower incidence of heart disease (7). The high circulating levels of antioxidants may reduce the effects of oxidation and prevent the damage caused by oxidized LDL cholesterol, which is involved in the development of atherosclerosis (8). Numerous clinical trials have evaluated the use of antioxidant supplements containing beta-carotene, vitamin C, vitamin E, lycopene and/or coenzyme Q10 in the prevention of cardiovascular diseases yielding conflicting (positive, neutral and negative) results. In many of these clinical trials there are enormous clinical design problems and methodological flaws with varied patient populations and variable dosage and type of micronutrient use that make the studies difficult to interpret. However, it is a fact that an adequate supply of antioxidant micronutrients is essential for cardiovascular health (9).

Latest research indicates that vitamin D deficiency is associated with a significantly increased likelihood of developing diabetes, hypertension, hyperlipidemia and peripheral vascular disease (10). Clinical trials of vitamin D supplementation to determine their use in prevention and treatment of such diseases and reduction of cardiovascular risk factors are urgently needed.

Antioxidants like beta-carotene and lutein may help protect the brain by neutralizing reactive molecules (free radicals) that can damage cells. A long term supplementation study (14) and some population studies (15) have shown that beta-carotene could improve global cognitive functions, particularly verbal memory. Lutein also improved verbal memory and fluency in an intervention trial (16) when supplemented together with omega-3 fatty acids.

The two omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have important biological functions in the central nervous system. DHA is a major structural component of neuronal membranes, and changing the fatty acid composition of neuronal membranes leads to functional changes in the activity of receptors and other proteins embedded in the membrane. EPA has important physiological functions that can affect neuronal activity. Studies are currently underway to investigate the effects of omega-3 fatty acids on Alzheimer’s disease (17) and age-related dementia (18).

Vitamin D may help preserve mobility. Not only is it a key nutrient that can reduce the risk of osteoporosis (19), studies also show that it reduces the risk of falling, a further decline in the chances of bone fracture (20). This reduction in fracture risk likely comes from vitamin D’s positive influence on muscle strength and reducing body sway (21). Experts now support significantly increasing recommended intakes of vitamin D after research showed that higher doses were more effective in improving health (22). An adequate supply with vitamin D is a particular problem for the elderly because the aging skin produces less vitamin D in the sunlight, and older people are more likely to spend more time indoors (23). Thus, an intake of vitamin D-rich foods or dietary supplements is recommended.

With age comes an increase in the number of joint problems. Vitamin C is a necessary nutrient for building cartilage, the tissue in joints between bones. Its importance in the management of healthy joints is supported by epidemiological studies (24). An increased intake of vitamin C has been associated with a reduced risk of gout (25). Vitamin E is an important antioxidant and is found in the fluid in joints, where it may play a role in their health (26). Low vitamin B6 blood levels have been associated with inflammatory joint conditions, possibly due to the pro-inflammatory conditions caused by vitamin B6 deficiency (27).

Omega-3 fatty acids have been shown to help reduce joint discomfort and stiffness: in a meta-analysis of 14 clinical trials in patients with rheumatoid arthritis or joint pain, an increased intake of omega-3 fatty acids showed a significant decrease in joint pain intensity, duration of morning stiffness, number of painful and tender joints and the use of pain relief medication (28).

In addition, vitamin A is an essential part of vision. The first signs of vitamin A deficiency, which can also be an issue for the elderly in developed countries, include night blindness, and persistent deficiency can result in total vision loss. Supplying an adequate amount of vitamin A or its precursor beta-carotene is vital for good vision (30).

In the eye, vitamin C is highly concentrated in the lens, where it works as an antioxidant. Numerous scientific studies have linked increased intakes of vitamin C alone (31) or in combination with other antioxidants such as vitamin E, beta-carotene and zinc (32) with long-term protective effects against the development of cataract and AMD in an older population.

Also the vitamins B9 (folate / folic acid), B6 and B12 have been shown to reduce the risk of AMD (33), probably by reducing the blood concentration of homocysteine, which is thought to be a risk factor for diseases of blood vessels, like AMD.

Furthermore, the omega-3 fatty acids docosahexaenoic acid (DHA), an important component of retinal pigment cells, and eicosapentaenoic acid (EPA) are vital for an optimal function of the eye. A high intake of DHA and EPA has been associated with a 40% reduction in the risk of AMD (34).

It has been suggested that nutrition may play a role in age-related hearing loss and that it may be associated with poor micronutrient status. Low serum folate concentrations have been found to increase the likelihood of having prevalent hearing loss by 39% (35). In addition, high concentrations of homocysteine – shown to be associated with a low folate status – are thought to increase the risk of cardiovascular disease and therefore may have an adverse effect on blood flow to the cochlea. Thus, an adequate intake of folate may reduce the risk of age-related hearing loss.

Other studies indicated that there is an association between higher intakes of omega-3 fatty acids and a lower risk of hearing loss (36). Therefore, dietary intervention with particularly eicosapentaenoic acid and docosahexaenoic acid, which were shown to have positive cardiovascular effects, could prevent or delay long-term the development of age-related hearing loss.

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