Winter is on its way...
...bringing the increased potential for colds and flu. Now is the time to start building up your immune system so you can stay well for winter. There are some key nutrients that you need to build your immune system, and interestingly they are in many of the seasonal vegetables that are around at the moment. All nutrients play a part in keeping us healthy and well, but with regards to building the immune system we will look at vitamins A and C, the mineral zinc, and some herbal remedies.
Vitamin A
This vitamin is important for keeping the mucus membranes in the nasal cavity healthy, to provide good defensive barriers against inhaled germs. Vitamin A also boosts the production of white blood cells, which help us fight infection, and stops virus replication, so in a way stops them in their tracks. Low vitamin A is linked with poor wound healing, repeat infections and night blindness.
Vitamin A is found in many yellow, orange and red foods, in the form of beta-carotene, which is converted to vitamin A in the digestive system. At the moment there are an abundance of root vegetables this colour such as carrots, pumpkin and golden kumara - so your mum was not lying when she said carrots could help you see in the dark. Persimmons are also a good source, and there are a number of green vegetables high in vitamin A too - they would be orange if they did not contain chlorophyll. Good sources around at the moment are spinach, cabbage, kale and other green leafy vegetables, along with brussels sprouts, broccoli, capsicum and celery. High sources available all year round are eggs and oily fish.
Vitamin C
Most people are aware that vitamin C can help prevent colds. It is used in every cell in the body and is important for the immune system. If we become ill it is quickly depleted, as it is a major component of white blood cells and also stimulates white blood cell production. Vitamin C is depleted by alcohol, certain medications (for example the oral contraceptive pill) and most significantly by smoking - so people taking medicines, or who smoke and drink regularly, will need more vitamin C than others.
Vitamin C can be found in most green vegetables, so we have double the reason to be enjoying the green leafy vegetables mentioned previously. Kiwifruit are an excellent source, as are feijoas and persimmons, and the other major fruit category is citrus fruits - so start enjoying those tangerines, oranges and lemons. It is worth noting that vitamin C is easily destroyed by heat, so eat some fruit and vegetables raw, and try to steam rather than boil when cooking.
Zinc
Zinc has antiviral properties and is released into the saliva to help kill any ingested bacteria and viruses. Like vitamin A it strengthens the barriers in the mucous membranes and is used extensively by the immune system. Studies show a 50% reduction in cold duration when taking zinc.
When you are enjoying those pumpkins for their vitamin A, don't throw away the seeds, as they are a rich source of zinc. Most nuts and seeds are a good source, as are beans, lentils and grains, so start making those hearty winter soups.
Herbal immune boosters
Garlic is a fantastic food with so many excellent properties. With regards to immunity it is anti-microbial, antiviral and anti-fungal - meaning it helps kill bacteria and viruses and boosts the immune system by increasing Natural Killer Cells. Many of these actions are due to the compound called allicin, which has been proven to induce an antibiotic action over the Staphylococcus aureus strain of bacteria and many other strains. Staphylococcus aureus is one of the bacteria causing respiratory infection, and as garlic is excreted through the lungs it is in the right place to kill it. Garlic can also help loosen a cough and with expectoration - so make sure you start adding it (and onions, which have similar antimicrobial properties) to your soups and stews.
Echinacea is a well known immune booster that can be taken to enhance the immune system or, if you fall sick, to help get rid of bacterial and viral infections quickly. One way it does this is by inhibiting an enzyme that invaders in the body use to enter the tissues, helping prevent a hostile takeover, as well as boosting production of the white blood cells that patrol the body and fight infection. There are 2 species of Echinacea, angustifolia and purpurea, and for immune boosting purposes a blend of both seems to work best. I also like this herb for sore throats, as it has local anaesthetic properties that help relieve the pain.
Astragalus is a herb used extensively in Traditional Chinese Medicine and is effective for exhaustion. It is a great immune system booster and also great for helping to support the stress response - so for those people who get completely over stressed and seem to fall sick all the time, this is a great herb. It can also help to support high blood pressure.
The digestive system
Since 70% of the immune system is in the digestive tract it is very important to start the winter with a healthy digestive system, and make sure you have plenty of good bacteria. Good bacteria look after the mucous membranes, help to increase T Cells for immunity and help us absorb our nutrients - this is why taking a probiotic at the start of the cold and flu season can be helpful.
I have also come across many people, especially children, who keep getting sick and being put on courses of antibiotics. These antibiotics kill the bad bacteria well enough (they do nothing for viruses), but they also kill the good bacteria - if probiotics are not taken alongside or afterwards the immune system is already at a disadvantage, and before you know it they are back on the antibiotics again.
Above all, look after yourself this winter - stay warm, get plenty of sleep, exercise, drink lots of fresh water and eat wholesome, nutritious and delicious foods.
