With winter here many of us will soon be getting our first seasonal cold or flu. Whether it’s a bug going around the office, or the kids coming home with the sniffles, it is pretty hard to avoid catching it ourselves.
Aside from isolating ourselves from the outside world the best way to reduce the likelihood of developing a cold or flu, or to reduce their symptoms, is to improve our immunity by living a healthy lifestyle. This includes eating a wide variety of healthy foods such as fruit and vegetables, ensuring we get regular exercise and plenty of sleep.
As we can see in any health shop or chemist there are a wide range of supplements which cater for the cold and flu season, but how do we know which ones will be of benefit?
Vitamin C
Fruit and vegetables are a good natural source of vitamin C and the recommended daily intake in adults is 45mg a day – the equivalent of one orange. Vitamin C has many roles in the body, including enhancing the function of the immune system. In a review of recent research, it has been suggested that taking vitamin C supplements at doses greater than 200mg a day may slightly reduce the duration and severity of cold symptoms but only when taken regularly, prior to catching a cold. Unfortunately it does not seem to reduce the likelihood of catching a cold.
Zinc
The recommended daily intake of zinc is 14mg for men and 8 mg for women. To meet these requirements we should eat a wide variety of foods containing zinc such as meat and nuts. For example 100g mince contains around 5mg and a handful of Brazil nuts contain 1mg. The remaining balance can be made up from small amounts of zinc found in other foods. Zinc is important for immunity as it is vital for cell development. Zinc supplements (15mg) have been shown to reduce the severity of colds in children when taken at onset of cold symptoms.
Zinc in the form of nasal sprays or lozenges has had mixed results with regard to reducing the severity and duration of colds, but all studies show it may cause irritation to the nose and throat taken in these forms.
Echinacea
There are three different Echinacea varieties commonly used in herbal supplements and three different parts of the plant (flower, stem or root) can also be used. This results in a large amount of variability between products, with differing levels of antioxidants and other compounds, which makes testing the efficacy of supplements challenging. It also means there is no standardisation when purchasing supplements and what we buy may not have the same properties as those used in studies. Of the research currently conducted Echinacea appears to have no effect on cold duration if you begin taking supplements when you first notice cold symptoms. The effect of Echinacea on how unwell you get and for how long when you have been taking supplements for a period of time prior to infection are in dispute, with some studies finding positive effects and others finding no effects.
Garlic
Garlic is a commonly used ingredient in many recipes. Since the availability of garlic supplements that have no odour, it has become a popular cold remedy due to its antimicrobial and antiviral properties. In one study garlic supplements have been shown to reduce the number of colds when taken for a period of time prior to infection. However there need to be more studies to determine if this is due to an effect, or by chance. High levels (found in supplements, not in dietary garlic) have been associated with rashes and may interact with Warfarin and other antithrombin medication. Garlic is often labelled as Allicin on packaging as this is the active component. One clove of garlic has around 18mg Allicin.
Vitamin D
Most of our vitamin D comes from the sun’s contact on our skin, and the chemical reaction that then happens in our body. Among other things vitamin D is known to regulate immunity and a deficiency has been linked to increased incidence of the flu. It is not surprising then that in the middle of winter, when we have not seen much sun for a month, we get more flu than any other time of the year. Depending on the weather and where you live it may be very hard to get your full exposure of sun required for adequate intake. There are very few good food sources, although some milks are now supplemented with vitamin D. Therefore supplements over winter may help.
Most of us should all be able to get sufficient nutrients from our diet for our health and wellbeing, but sometimes work and family life can leave us feeling we are not quite there.
Like all nutrients the ones discussed above can be detrimental or toxic in extremely high doses. Therefore when taking supplements ensure you follow the recommended dose, and if in doubt stick to levels near the recommended daily intake, or speak to your GP.