Now more than ever we need to look after ourselves. Dietitian Orla Walsh on the essential nutrients that support our immune system and how to eat them
In the coming months, lots of us will be looking at all areas of our life to help protect our own bodies. The overall function of the immune system is to prevent or limit infection. The immune system is good at differentiating between normal healthy cells and unhealthy ones. Infectious microbes release signals that the immune system recognises causing a response to deal with the problem. Infection arises when the bugs get ahead of the immune system. When it comes to nutrition, there are some areas that you could focus on in a bid to better support your immune system.
First and foremost, it's important to eat enough. Calories are needed to feed all systems in the body, including our immune system. On average women need about 2,000 calories a day while men require about 2,500 calories a day. It's important to try and eat enough, which may be challenging if you are sick. If sick and off your food, the 'little and often' approach is advisable as well as eating foods that you feel you can eat. Trust your gut! You may find it helpful to eat dry, plain and cold foods. Additionally, consuming calories through fluids may be easier. However, if you are not sick, it's a good idea to avoid calorie-restricted diets, especially those with large calorie deficits. A healthy diet does support the immune system. Some nutrients are worth focusing on.
Vitamin A is an antioxidant vitamin with many roles including supporting normal immune function. Additionally, vitamin A helps to keep our skin healthy as well as the mucous membranes in our mouth, stomach, intestines, and our respiratory system healthy. As our skin and mucous membranes act as one of the first barriers to infection, it's important that we nourish them. A supplement is often not required. There are two types of vitamin A: vitamin A from animal produce such as meat, dairy and eggs, and vitamin A from plants such as oils, leafy greens and yellow/orange vegetables. Aim to eat these foods often.
Vitamin C is an antioxidant vitamin that plays an important role in immune function. Since the 1930s, vitamin C has been proposed for treating respiratory infections. It became particularly popular in the 1970s when it was suggested to prevent and treat the common cold. Lots of trials have been completed since. A review from 2013 which included 29 trials and over 11,000 people stated that vitamin C supplementation had no effect on the incidence of the common cold in the general public. A review of five trials and nearly 600 participants showed that a vitamin C supplement halved the risk of the common cold in athletes. However, a regular supplement had a modest and consistent effect in reducing the duration of common cold symptoms, with results being higher in children. This is based off results from 31 studies with nearly 10,000 episodes of common cold.
The trials within this review didn't support taking vitamin C once you got a cold as it didn't impact duration or severity. Like all supplements, and despite being a water soluble vitamin, vitamin C is not healthy in large doses. As fruit and vegetables are such great sources, it may be beneficial to focus on eating your seven-a-day instead. For example, requirements are easily met if you eat red peppers.
Vitamin E is another antioxidant vitamin that has a role in supporting immune function. Naturally occurring vitamin E occurs in eight different chemical forms with varying levels of biological activity. Alpha-tocopherol is the one us humans need to focus on. Generally, a supplement isn't needed. Nuts, seeds, and vegetable oils are among the best sources of alpha-tocopherol, as well as green leafy vegetables. For example, sunflower seeds, almonds, hazelnuts and peanut butter are rich sources.
Zinc has an important role in supporting immune function. Although zinc is an essential mineral that is naturally present in our foods, it is also found in many cold lozenges and some over-the-counter drugs.
This is because researchers suggest that zinc could reduce the severity and duration of the common cold by inhibiting rhinovirus in the nasal passage and by suppressing inflammation. Studies have provided conflicting results.
Nevertheless, zinc does appear to help in certain circumstances. Lozengers and zinc-containing syrups may be the preferred choice as they spend more time in the mouth. Oysters are an incredibly rich source of zinc. However, beef, pork, baked beans and pumpkin seeds are everyday foods that will help you meet your zinc requirements.
Vitamin D is a fat soluble vitamin that is naturally present in few foods. Researchers have suggested that taking Vitamin D supplements may enhance resistance to respiratory infections such as Covid-19, or limit the severity of the illness for those that do become infected.
The opinion of Dr Daniel McCartney and Dr Declan Byrne was published in the Irish Medical Journal last week. They recommended that adults living in this part of the world take 20-50 micrograms of vitamin D per day for the next three to six months as a short-term measure to specifically address the risk of COVID-19. Vitamin D deficiency is common here. Those at greater risk include older people, nursing home residents and hospital in-patients.
This level of supplementation should only be considered as a short-term measure which may potentially help those who are deficient in vitamin D or potentially deficient in vitamin D.
It is advisable that a person should only take this amount of vitamin D under the guidance and supervision of their doctor. The current recommended dose is 200-400 IU. Oily fish and eggs are sources.
Echinacea is widely used to reduce the risk and symptoms of a common cold, despite having limited evidence for it.
A big problem with the studies that have been conducted is that one echinacea product differs quite greatly to the next one. Like other supplements, sometimes other herbs are also added.
A review of the literature was done. However, due to all the differences in supplements being tested, it was difficult to draw any strong conclusions.
Nonetheless, it does seem that some echinacea products may be effective at treating colds. Although, the overall evidence is weak.
There have been a number of studies investigating the impact of particular strains of probiotics on upper respiratory tract infections and the immune system in athletic cohorts ranging from healthy active people to elite athletes.
Unfortunately, it's hard to draw guidelines from these studies, even though the evidence for use is building, as different types of probiotics are used within these studies. Additionally, differences in the effectiveness relate to the type of sport, the training history of the person, and the training load they're undertaking. For the general population, it's important to note that the gut appears to play an important role in immune function.
One of the most important areas to focus on when trying to improve your gut microbiome is to aim for a varied diet with lots of different types of plants. However, it's likely with time that more specific guidance will emerge.
Eating a healthy varied diet is the best way to support your immune system with food. Supplements can sometimes be referred to as the 'sprinkles on the icing of the cake'.
Covid-19 is new so no research has been completed on diet, nutrients and the likeliness of infection, severity of infection or duration of infection. Therefore, nutritional practices for the common cold are simply nutritional practices for the common cold. The most important steps with regards to Covid-19 remain hand hygiene and social distancing.
However, it will certainly do no harm to focus on eating lots of the foods mentioned above, taking your vitamin D supplement to prevent deficiency and eating a variety of plants to support a healthy gut microbiome.
Ingredients: 350g wholemeal flour;125g plain flour; 20g wheatgerm; 20g wheat bran; 1 tsp bread soda; 1 tsp salt; 500ml buttermilk.
1. Preheat your oven to 200°C.
2. Mix all the dry ingredients in a bowl.
3. Add the buttermilk & mix well. 4. Grease a bread tin. Spoon in the contents. Bake for 10 min then turn down the heat to 180°C and bake for another 40 mins.
BAKED EGGS IN RED PEPPER CUPS
Ingredients: 1 red pepper, oil spray, 2 eggs
1. Preheat the oven to 175°C.
2. Slice the pepper in half.
3. Place on a baking tray.
4. Crack an egg into each half.
5. Bake until your eggs are cooked to your preference.
POSH BAKED BEANS
Ingredients: 2 tbsp pumpkin seeds;
2 slices of brown bread; 200g baked beans; olive oil; half a garlic clove.
1. Heat a frying pan. Dry fry pumpkin seeds.
2. Toast brown bread.
3. Meanwhile heat your beans in a pan.
4. Brush your toast with olive oil and rub with garlic.
5. Place beans on top.
6. Sprinkle with pumpkin seeds.