Having just delivered a lecture to Year 1 students regarding the influence of nutrition on the immune system, this seems like the perfect time to write a short blog piece on a related topic.
At this time of year, many of us find ourselves struggling with a cold, or even perhaps the flu, particularly if your daily routine involves a commute on a train or tube packed with coughing and sneezing commuters! In the UK, it is well documented that the frequency of catching a cold increases rapidly in autumn and winter and adults are estimated to have 2-4 common cold episodes annually. If you have school-age children, you will find yourselves even more exposed to an array of infections and young children will typically have 6 common cold episodes each year (although this could also be as high as 12).
So what can you do to help support your immune system during the winter months?
Firstly, ensure your diet is rich in plant foods, particularly colourful fruit and vegetables. Plants contain thousands of biologically active compounds, or phytochemicals, which have been shown to have immune boosting properties, with many also having direct antiviral effects. For general health, eating ‘a rainbow’ of fruit and vegetables ensures that you have a varied intake of phytochemicals, since these are also the chemicals which give the foods colour.
Particularly beneficial fruits for supporting immunity include:
Blueberries, which contain pterostilbene, a phytochemical which has been shown in lab studies to work with vitamin D, increasing the production of an antimicrobial protein used by your immune cells to kill viruses.
Pomegranates, used by the Ancient Egyptians to treat a number of different infections, contain active compounds which have been shown to directly inhibit viruses invading cells and replicating
Citrus fruits, rich in vitamin C. White blood cells actively accumulate vitamin C to concentrations 50-100x greater than the surrounding plasma, suggesting a crucial role for vitamin C in immunity. In fact, studies show that vitamin C influences many aspects of immune cell function, including their ability to move to sites of infection and to engulf and kill invaders, including virus infected cells.
Vegetables are also powerful additions to your immune-boosting diet, with my favourites being:
Delicious in a stir-fry or soup, shiitake mushrooms are one of the edible ‘medicinal mushrooms’ and contain several components (e.g. a beta-glucan called lentinan) which have been shown in lab studies to reduce the ability of viruses to reproduce. Lentinan has also been shown to have powerful anti-carcinogenic properties, stimulating destruction of tumour cells by a type of immune cell called natural killer cells.
Well recognised to have broad-spectrum anti-microbial effects, garlic is a super addition to the diet. Most studies tend to investigate the effect of allicin extracts, a sulphur containing compound derived from garlic, on the incidence and duration of the common cold, however some recent evidence found that a single meal containing raw, crushed garlic (5g) was sufficient to ‘turn on’ genes which play an important role in immune cell development and function. Raw, crushed garlic can be easily included in salad dressings, pesto, hummus and guacamole.
Your immune system is also very dependent upon protein to function (e.g. fish, meat, eggs or vegetarian sources such as beans and lentils). Protein serves as the raw material for building immune cells and for many other different aspects of immunity, including antibody production for example. Whilst most of us do eat sufficient protein, this is something to bear in mind.
A palm-sized serving of protein at each meal is a good visual guide to aim for. Although red meat in excess (or processed) can contribute to a number of health problems, 1-2 servings of good-quality red meat per week (organic, grass-fed, unprocessed) can provide a valuable source of zinc, a mineral which is absolutely essential to immune function. Zinc plays a key role in the ability of immune cells to divide and increase in number to deal with an active infection and also increases the effectiveness of these immune cells.
Vitamins and minerals
There are many other nutrients essential for immunity (e.g. vitamin A, selenium, vitamin D), as well as foods which may be beneficial (e.g. Manuka honey, oily fish).
If you suffer from many colds and infections, it would be worth consulting with a BCNH qualified nutritional therapist to help you identify and address underlying factors which may be suppressing your immune system. They can also advice you on the many good supplements on the market which can make a significant difference in terms of shortening the duration and severity of a cold.
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