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Colds and flu

08 June 2018

How to protect your immune system – straight from a dietitian

Looking to boost your immune system? Here are some tips from a dietitian.

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There are so many health myths out there. Linda Drummond, a registered dietitian and spokesperson for the Association for Dietetics in South Africa, says she believes myths are a result of mixed messages given to the public by a number of sources that are not necessarily experts in the field of nutrition – for example, family members, friends, non-nutrition professionals and supplement companies.

“Because food and nutrition are so much a part of everyone’s life and people have their own experiences in this area, many may feel that they can provide an opinion and that theirs is the truth.”

Here are two common opinions (that you should stop believing):

Myth 1: ‘I just need to take a multivitamin or more vitamin C to boost my immune system during winter’

“While vitamin C does play an important immune-boosting role, research has shown that supplementing with Vitamin C does not actually help you to avoid developing colds and flu," says Drummond. "Studies have found that in some, but not all cases, vitamin C, as an isolated strategy, may help to reduce the duration of the illness, but not protect you from it.”

She adds that nutritional supplements can play an important role in supporting improved health for vulnerable people, such as children, the elderly, pregnant women and those with health conditions that compromise their immunity. For the rest of us, however, we should aim to get our daily intake of immune-boosting micronutrients from our food. Foods like vegetables, fruit, wholegrains, dairy, meat, chicken, beans and lentils provide vitamin C, immune-boosting vitamins like A, D and B, plus trace elements such as zinc and selenium.

“You cannot expect that if you eat poorly, but take a supplement, your immune system will still be highly effective. What you eat, not what you supplement with, is what is most important to build your defences against winter germs. Supplements are not an antidote to unhealthy eating. They can help to fill in gaps in an otherwise healthy eating plan, and you should get your dietitian’s advice on this. However, we should all be clear that when it comes to what we consume and our immune systems and our health, there is simply no substitute that we know of at this time that beats the effectiveness of eating a variety of quality, minimally processed foods, which are mostly plant-based, every day.”

Fresh orange juice

Myth 2: ‘To improve my immunity in winter, all I have to do is focus on the food I eat and the supplements I consume’

“This is false,” says Drummond. “While healthy eating is a vital immune boosting strategy, and nutritional supplementation may be necessary for you if you have a compromised immune system, it remains one critical aspect of having an effective immune system during the challenging winter months. But, it is a complex system and other factors are at play.”

Foods to focus on

Our bodies need a number of nutrients to support the normal function of our immune systems but lifestyle factors also play an important role. “Eating foods in season is a good strategy to follow, as these foods tend to contain nutrients you need to be sure you are getting enough of during the months they are grown in,” says Drummond.

“They are also more affordable, as they tend to be grown locally at that time and not imported. Although vitamin C is only one key nutrient for normal immunity, more vitamin C-rich foods tend to be available during the winter months, such as guavas, grapefruit and oranges.”

When to supplement

Drummond says supplements should be reserved for cases when you know your diet is lacking certain nutrients. “That is when you are taking in less of or avoiding certain foods known to be key sources of nutrients.” She says a registered dietitian is a nutrition expert and would be able to advise you when a supplement may be necessary due to poor intake or exclusion of foods.      

“You can have blood tests done to determine whether you are suffering from a deficiency of a particular nutrient such as iron or vitamin D. In these cases, supplements are prescribed to address the deficiency. Supplementation is stopped after the deficiency is addressed, as confirmed by follow up test results.”

But she also adds that it’s often better to get your nutrients through food rather than supplements, for two reasons:

1. Food generally contains nutrients in the correct amount and form for absorption by your body. There are some exceptions, however, as some foods are better sources of a particular nutrient than others e.g. iron from animal vs. plant foods.

2. Plant foods contain phytonutrients (not generally found in supplements) that are key for health, but not as well understood.

A dietitian’s top tips for boosting immunity

As a mother of two young children, Drummond says it’s not that she doesn't get sick during winter. “Young children just don’t allow moms time to just go to bed and get better,” she says. “And, on top of that, young children tend to get sick more frequently due to being around other children all the time – so the risk of getting ill is higher for me."

Her personal strategy is:      

  • To eat a wide variety of nutritious foods including plenty of vegetables – which she gets through homemade soups and by adding extra to dishes whenever possible.
  • To increase her phytonutrient intake and maintain her fluid intake through teas with herbs and spices.
  • To continue exercising for its health benefits, as well as stress relief, but keep warm afterwards.
  • To control her body temperature through clothing instead of artificial heating, thereby not reducing her supply of fresh air.
  • To get a little extra sleep by going to bed slightly earlier whenever possible.

 Image credit: iStock

 

Ask the Expert

Flu expert

Dr Heidi van Deventer completed her MBChB (Bachelor of Medicine and Bachelor of Surgery) degree in 2004 at the University of Stellenbosch.
She has additional training in ACLS (Advanced Cardiac Life Support) and PALS (Paediatric Advanced Life Support) as well as biostatistics and epidemiology.

Dr Van Deventer is currently working as a researcher at the Desmond Tutu Tuberculosis Centre at the University of Stellenbosch.

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