Topic of the Month

Key nutrients in the prevention of eye diseases

In Topic of the Month · December 1, 2014

Optimizing vision throughout the lifespan is a public health priority worldwide, not only because of its central importance to quality of life, but also because of the health care costs associated with the loss of vision in an aging population. Oxidative stress is thought to be a key pathogenic mechanism of compromised vision, and the antioxidant properties of some nutrients show the capacity to modulate disease conditions linked to oxidative stress. Considerable evidence has accumulated showing that vitamins A, C, E, beta-carotene and zinc help support vision and may be protective against the development or progression of some common – especially age-related – eye diseases such as age-related macular degeneration and cataracts. In addition, increased intakes of the carotenoids lutein and zeaxanthin and the omega-3 fatty acid docosahexaenoic acid (DHA) – all concentrated in the eye – have been associated consistently with lower likelihood of sight-threatening conditions. There has also been some promising research with B vitamins in age-related eye diseases and with vitamin A and DHA in the rare disease retinitis pigmentosa (see also Key nutrients for healthy vision).

Topic of the Month

Key nutrients for healthy vision

In Topic of the Month · November 1, 2014

The eye is rich in nutrients and other dietary components that support and complement each other. Some nutrients are necessary for the basic physical structure of the eye, some for the physiology of sight, and others for protection. Nutrients within the visual system can be thought of as a hierarchy representing a complex of interacting factors: while vitamin A (retinol) is essential for the formation of visual pigments, the antioxidants vitamin E, vitamin C, lutein and zeaxanthin help to protect the lens and retina against light-induced oxidative damage, and the long-chain omega-3 fatty acid docosahexaenoic acid (DHA) enriches neural tissues including the photoreceptor cells. These nutrients are known to be important for visual development early in life, starting from the fetus through infancy to early childhood. Visual acuity gradually improves until about age four, when it is comparable to that of adults. For adults a sufficient intake of these nutrients is needed throughout the lifespan to maintain visual performance, such as the ability to adapt to low light, recover from intense light and distinguish objects from their background.

Topic of the Month

The safety of micronutrients – Part 3: minerals

In Topic of the Month · October 1, 2014

As concentrated sources of micronutrients designed to supplement the normal diet, dietary supplements can be used to balance specific dietary deficits or to ensure adequate intakes. However, in some cases too high an intake of micronutrients can have adverse effects on health or cause undesirable side effects; for this reason it is necessary to define maximum intakes to guarantee the safety of their use in dietary supplements. Since the European legislative authority has not yet established uniform maximum intakes across the whole of Europe, manufacturers of dietary supplements and fortified foods are guided by recommended daily amounts and scientifically recognized upper limits for safe total daily intakes. This also applies to safe intakes for minerals present in the body, whether as macro-elements in concentrations of at least 50 mg per kg dry body weight, or as trace elements (micro-elements) in concentrations of under 50 mg per kg body weight (see also The safety of micronutrients – Part 1: fat-soluble vitamins and Part 2: water-soluble vitamins).

Topic of the Month

The safety of micronutrients – Part 2: water-soluble vitamins

In Topic of the Month · September 1, 2014

Insufficient and excessive consumption of nutrients can both increase the risk of damage to health. As intake is increased, the risk of developing a harmful nutrient deficiency falls until the intake reaches an amount that is regarded as adequate (recommended daily amount). Above this amount (tolerable upper intake level or UL) toxic effects may be seen that once more increase the risk of damage to health. How the body reacts to the consumption of specific micronutrients depends on the dosage and on the consumer’s baseline nutrient status. If nutrient levels are already high, increasing consumption is likely to increase the risk of toxicity. With vitamins as with all nutrients: more is not always better. This also applies to water-soluble vitamins, although these do not accumulate in the body to the same degree as the fat-soluble vitamins (see also The safety of micronutrients – Part 1: fat-soluble vitamins).

Topic of the Month

The safety of micronutrients – Part 1: fat-soluble vitamins

In Topic of the Month · August 1, 2014

Excessive intake of high-energy macronutrients and their potential consequences for people’s health are a problem in many industrial nations. In the case of micronutrients, however, epidemiological data suggests that over-supply is the exception rather than the rule across the globe. Many people are therefore concerned that their dietary habits are failing to provide them with a sufficient supply of essential nutrients such as vitamins and carotenoids. Given that intakes of some nutrients are below officially recommended levels, it might at first sight appear unnecessary to set upper intake levels for micronutrients. However excessive intake of food supplements and fortified foods in addition to normal diets could conceivably lead to intake levels which could potentially be considered harmful. It may be sensible to define an upper daily intake level at which the risk of adverse effects on health is unlikely, particularly in the case of fat-soluble vitamins which are stored in small quantities in the body.

Topic of the Month

The importance of vitamin K for health

In Topic of the Month · July 1, 2014

It has long been known that vitamin K, which is involved as a coenzyme in the production of coagulation factors, is essential to the regulation of blood coagulation. But vitamin K also fulfils an important role in the activation of certain enzymes which, together with vitamin D, regulate metabolism and can combat the hardening of soft tissues such as blood vessels and help slow bone demineralization. In recent years interest in this vitamin has grown considerably following the discovery of other potentially health-promoting properties. Attention centers on research into the function of vitamin-K-dependent enzymes (Gla proteins), which are found in bones and teeth as well as in blood vessel linings, the brain and other soft tissues, where they appear to regulate cell division and cell differentiation, among other things. Studies indicate that a sufficient intake of vitamin K could help prevent the occurrence of atherosclerosis, osteoporosis, insulin resistance and inflammation of the joints, and above all could protect against the age-related loss of cognitive abilities.

Topic of the Month

The importance of omega-3 fatty acids for health

In Topic of the Month · May 1, 2014

The formation of cell membranes as well as many other physiological functions crucially depends on the availability of sufficient amounts of the omega-3 fatty acids docosahexaenoic acid (DHA) and eico- sapentaenoic acid (EPA). Omega-3 fatty acids appear to have a key function in the formation, growth and regeneration of cells and in the transmission of cell signals throughout life. During pregnancy and breastfeed- ing the essential polyunsaturated fatty acids are already playing an important role in the development of the infant brain and eye cells. Studies found that omega-3 fatty acids could also improve sight and brain function in adults. Fatty acids are needed for the production of hormone-like substances (eicosanoids) which act in the body in multiple ways. Hence fatty acids appear to be involved in the regulation of lipid metabolism, blood pressure, immune system, inflammatory processes and psychological wellbeing. An adequate intake of ome- ga-3 fatty acids could therefore help in the prevention of many diseases.

Topic of the Month

The role of carotenoids in disease prevention

In Topic of the Month · April 1, 2014

Many studies have linked the regular consumption of carotenoid-rich foodstuffs to a reduced risk for the incidence of a number of diseases. Under discussion as basic mechanisms for this protective effect are the antioxidant activity of carotenoids and their biochemical ability to influence signal transmission in cells. A sufficient intake of carotenoids to support the body’s own antioxidative network could therefore combat the development of diseases that are stimulated by oxidative damage to cell constituents. Since these micronutrients are fat-soluble they act mainly in cell membranes and lipoproteins to protect against excessive oxidation. There they can help prevent cell mutation – and therefore the development of cancer – and the formation of atherosclerosis, which is a cause of cardiovascular disease.

Topic of the Month

Micronutrients and eye health

In Topic of the Month · March 1, 2014

Good eyesight requires the thousands of cells which compose the eye to all function well. The cells, in turn, rely on an adequate supply of micronutrients to support and maintain their function. Several vitamins are needed as co-factors for the enzymes involved in sight. Vitamins are also important to the optical nerve that transmits light signals from the eye to the brain; to the muscle cells that facilitate visual acuity; and to the blood vessels that are responsible for supplying the eyes with blood and nutrients. The carotenoids found in the macula lutea, the yellow spot at the center of the retina, filter short-wave light like natural sunglasses and protect this sensitive area of the eye against UV damage. In addition, omega-3 fatty acids protect the retina and are indispensible for sensory cell function and hence for vision.

Topic of the Month

Micronutrients and the immune system

In Topic of the Month · February 1, 2014

The task of the immune system is to protect the organism against harmful external influences, e.g., microorganisms. One consequence of an immune reaction is inflammation, which serves to remove foreign bodies or pathologically altered cells. However, if the immune reaction is not appropriate it may lead to undesirable effects, including increased vulnerability to infections if immune function is diminished, or allergies, autoimmune diseases and chronic inflammation in the case of hyperfunction. To fulfill its many and various protective and signaling functions, the immune system relies on the adequate availability of micronutrients. Potential deficiencies can affect both unspecific (innate) and specific (acquired) immunity.