US intake recommendations for vitamin D increased
A new report from the US Institute of Medicine has set out new, increased, dietary recommendations for calcium and vitamin D.
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.
While the march of the years cannot be stopped, some lifestyle factors can increase the chance for healthy aging: not smoking, regular exercise, maintaining a healthy weight, a moderate alcohol intake plus eating a balanced, micronutrient-rich diet including plenty of fruit and vegetables. Elderly people are at increased risk for micronutrient deficiencies, and should ensure adequate intake (1, 2).
The aging process
By the age of thirty, most age-related biological functions have reached a peak and start to gradually decline. Age-related changes can affect the function of individual cells and organ systems. The rate at which cells multiply tends to slow down with age, decreasing the number of specialized cells important for bodily functions such as the immune system. Thus, age causes changes in the responses to environmental stresses or exposures, such as ultraviolet light, heat, oxygen deficiency and poor nutrition. In addition, age interferes with “apoptosis,” which programs cells to self-destruct or die at appropriate times. Changes in this program can affect the development of different diseases that are common in elderly people. For example, cancer results in a loss of apoptosis, making cancer cells continue to multiply and invade or take over surrounding tissue, instead of dying as originally programmed. In Alzheimer’s disease, brain cells die too early resulting in a progressive loss of memory and other brain functions. Consequently, a number of age-related health concerns, such as cardiovascular disease, osteoporosis, dementia and nutritional deficiencies, need particular attention.
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.
Keeping the cardiovascular system healthy is an important concept in aging. Along with avoiding smoking, maintaining a healthy weight and engaging in regular exercise, an adequate intake of omega-3 polyunsaturated fatty acids is believed to support heart and blood vessel health (3). Several observational studies and clinical trials have shown beneficial effects, specifically for eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), in primary and secondary cardiovascular prevention (4). Further studies are needed to determine optimal dosing and the relative ratio of DHA and EPA that provide maximal heart protection.
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.
Cognitive functioning affects the capacity to lead an independent, fulfilling life: it impacts memory as well as the capacity to process complex thoughts and is essential for social activities. It is well-documented that significant vitamin B12 deficiency can lead to reduced cognitive performance (11). Study results indicate that seniors may need to maintain higher levels of vitamin B12 in the body than younger people to prevent declines in mental facilities because of deficiency (12). At the same time, the risk of a deficiency because of an impaired absorption of food-bound vitamin B12 increases with age. Vitamin B6 is a related micronutrient that also contributes to maintaining cognitive function, particularly in elderly populations (13).
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).
Staying mobile is very important for getting the most out of life as one ages. Especially at an advanced age, activities like visiting the supermarket, housework, sport or even just getting out of the chair may become difficult. The general decline in muscle mass with aging is partly responsible for reduced mobility, but conditions such as arthritic joints, weak bones and general endurance also play a role.
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).
Vision changes throughout life, is influenced by lifestyle and declines with age. Science suggests that proper nutrition can help to maintain eye health, preventing or delaying the progression of eye diseases such as age-related macular degeneration (AMD) andcataracts. Damage from light to the sensitive photoreceptor cells in the macula is thought to be involved with the development of AMD. A number of epidemiological studies show that dietary intake of lutein and zeaxanthin is associated with a lower risk of developing AMD (29).
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).
Age-related hearing loss is a common health problem in the older population, implying a considerable burden not only for sufferers, but also for those with whom they communicate. Most hearing loss in the elderly is associated with a dysfunction of the auditory portion of the inner ear (‘cochlea’). In addition, factors such as noise pollution and ear infections can enhance the hearing loss process.
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.
A new report from the US Institute of Medicine has set out new, increased, dietary recommendations for calcium and vitamin D.