The immune system is frequently overworked when the days get shorter and the temperature starts to drop, and elderberry can boost the immune system in winter for those that find themselves susceptible to all the colds, flu and other viral infections that seem to come out of the woodwork at that time.
Elderberry is the fruit of the elder tree that is native to Asia, Europe and North America. They are found just about anywhere due to their tolerance for a wide range of climates and soil types, and are frequently found by river banks. There are a number of different types of elder, in both small tree and shrub form, and it is those with the black and blue berries that are useful medicinally, not those with red berries. It is not only the berries that are used, but also the elder flowers. Elderflower wine has long been a favorite country wine, and the berries are used to make jam, pies and also drunk as juice.
Elder has been used for countless years for treating viral diseases such as influenza and colds, and it has also been found by some to be effective for the treatment of cold sores (herpes simplex). Its effect on flu is thought to be that it prevents the virus from entering and infecting the body cells, but more on this later. Historically, it has been used to promote the excretion of waste products through urination and sweating, which might be another reason why it is effective against colds and flu and some general respiratory problems.
The juice contains anthocyanins in the form of anthocyanidin-3-glycosides that appear to be very bioavailable to the body. The anthocyanins are more easily absorbed than those of blackcurrant juice, and are very strong antioxidants. The antioxidant effect is reinforced by the presence of large quantities of vitamin C. This difference in bioavailability has been proved though the administration of both blackcurrant and elderberry juice to volunteers, and testing the presence of the anthocyanins in the urine. This is a measure of their bioavailability, or how easily they are absorbed by the body, and the greater this bioavailability, then the more effective is their antioxidant effect.
Separate studies have indicated that anthocyanins derived from berries in general, not just elderberry, can reduce oxidative stress due to age, and also to help brain function. An improvement in the memory of the elderly has been seen to have improved after a course of berry juices rich in these powerful antioxidants. Elderberry antioxidants also improve the stability of LDL cholesterol by protecting against free radical oxidation, and thus helping to reduce the incidence of atherosclerosis that is promoted by the deposition of the oxidized LDL cholesterol on artery walls. This in turn helps to reduce the possibility of cardiovascular disease.
However, it is its effect on the immune system for which elderberry is generally studied by the medical professions. Elderberry helps to boost the immune system predominantly through the production of cytokines. To explain how these work, a quick summary of how part of the immune system works will first be necessary.
When intrusion into the body by an antigen (foreign body) is detected, the initial response is the inflammatory response. Chemical messengers called cytokines are released into the blood to inform the other parts of the immune system that an invader has been spotted.
The immediate effect is to increase the flow of blood to the affected part of the body by dilation of the blood vessels. The spaces between the cells in the vessel walls increase to allow the larger components of the immune system, such as the phagocytes that consume and destroy bacteria. Proteins also congregate and the temperature at the site rises to promote the reactions that the body uses to eject the invaders. The tissue therefore swells due to all the extra fluid and gets hot. The area becomes painful due to the accumulation of material aggravating the nerves, and if there is an infection, pus will eventually be formed from the dead neutrophils used to kill the bacteria or virus.
There are many different types of cytokine, including those that initiate the inflammatory response and others that stop the immune response once the invader has been killed off. Other cytokines, such as the interferons, stop viruses from multiplying, and others take part in the response only to specific types of antigen. Each cytokine has a specific message to pass to the relevant components of the immune system in order that the immune response is appropriate to the invasion concerned and does not overreact. Hence, a grain of pollen in the nose will elicit a lesser response than a varicella antigen that leads to those horrible chickenpox pustules.
In general terms, cytokines give the immune system a kick start once an antigen is spotted. The elderberry anthocyanins produce predominantly inflammatory cytokines, but also one anti-inflammatory cytokine, and so helping to boost the inflammatory response.
Some viruses use what are known as spike proteins that mimic the molecules of their host in order to gain access to cells by binding to the target cell receptors. However, these spikes are easily recognized by the immune system, and the elderberry anthocyanins are active in promoting this recognition. For that reason, viruses vigorously continue to change and mutate to overcome this, one manifestation of their success in achieving this being in the annual infections of influenza that have overcome last year's antibodies by means of this mutation.
The influenza virus contains what are known as hemagglutinin spikes on its surface which, when deactivated, cannot break through your cell walls, enter the cell and replicate, thus leading to influenza. That is the mechanism by which the constituents of elderberries help to control influenza and reduce its effect on your body. If not deactivated, the spikes allow the virus to invade the cell and provoke the immune response that you know as the flu.
Many such winter ailments have a similar mechanism, which is why, apart from its general health benefits through its high antioxidant content, that elderberry can boost the immune system in winter.