Supporting your immune system through diet and nutrition

From achieving herd immunity through to promoting vaccine-based immunity, it's probably fair to say how best to boost our immune system to fight disease and promote good health and wellbeing has rarely been higher on the agenda.

This has made a recent 'vlog' (or video blog) by Clarissa Lenherr, Harley Street nutritional therapist, on ways to use diet and nutrition to support your immune system especially timely.

"Over the past however-many-months our immune systems have had a bit of a spotlight," highlights Clarissa. "There has been a lot of information circulating about the immune system: what we can do, what we shouldn't do, the things that can impact it, the things that can boost it."

That is where authoritative online information has real value in helping us to navigate what can be a complex and potentially confusing area, especially in terms of individual health and wellbeing.

Clarissa explains what the immune system is and the difference between an 'innate' immune system response and an 'acquired' immune system response.

"The innate immune system response is what we're born with. It is mostly cells and proteins, which work to protect us. They are like an army in the body that fights off viruses, bacteria and pathogens," she outlines.

"The acquired immune system is not something we are born with; it is activated by exposure to things. You are exposed to a virus, a pathogen, a foreign antigen, and you produce antibodies.

"These antibodies create an immunological library. We've been shown this foreign antigen, we've produced antibodies and an immune system response and we [our bodies] have remembered this. It means next time we are exposed, whatever this pathogen, virus or bacteria is, we have already dealt with it. Being exposed to certain things can give us a sense of immunity for however long a period of time."

Not many people realise that 70% of our immune system is located in our digestive system, digestive tract, she highlights. "So, making sure we are looking after our digestive health is really important for looking after our immune system and inflammation levels as well."

How, therefore, can nutrition and diet help to stimulate and protect our immune system? "We want to try to avoid a diet heavy in sugary foods," Clarissa recommends. "Those who consume lots of refined sugars unfortunately have a dampened immune system response. So, trying to make sure you're not having more than 30g of sugar, which is the recommended amount in the UK for adults per day."

Highly processed foods, such as burgers and pizzas, are very low in nutrients, she points out. While we do of course all need our comfort foods and the occasional 'bad' meal is not going to be the end of the world, the key is making sure your diet doesn't become dominated by less nutrient-rich foods.

It also stands to reason that not overdoing it on the alcohol will help. "Try to stay below 14 units of alcohol a week, because alcohol can affect our quality of sleep, our stress, our digestive system, our immune system and more," says Clarissa.

Taking vitamin C first, this is the vitamin everyone tends to associate with boosting our immune system vitamin. "What's important with vitamin C is the body cannot make it, unlike vitamins D and B. We rely solely on dietary intake," advises Clarissa.

"The good news is that if you're eating your minimum of five portions of fruit and vegetables a day you should be able to get enough vitamin C," she adds, though highlighting that broccoli and tomatoes are also good sources of vitamin C. "So, focusing on vegetables will also give you lots of other nutrients. Strawberries are also good, as are other citrus fruits like grapefruits, lemon juice and so on," Clarissa advises.

In the context of Covid-19, vitamin D has rarely been more in the spotlight. The fact there are indications it can help to prevent severe health outcomes from a Covid-19 infection means "it has received superstar status over the past year and a half.".

The best source of vitamin D is from sun exposure on our skin. The UK recommended daily intake of vitamin D is 400 'international units' or 10 micrograms per day. Therefore, Clarissa argues, it can be worth those who live in countries with less sunlight during the autumn and winter (such as the UK) taking a vitamin D supplement of 10 micrograms between October and April to prevent deficiency.

"Vitamin D is crucial when it comes to the immune system. It plays such an important role in enabling the cells and the proteins in our immune system. In addition, it plays a role in mood, energy production, bone health, gut health, and so much more," she says, though adding that you can get some vitamin D through dairy products and mushrooms.

Zinc, Clarissa explains, is important for wound healing as well as building general immunity to infection and illness. "The best source of zinc can be found in things like seafood, shellfish, red meat. Those on vegetarian and vegan diets might just need to be a little bit more organised in getting in more zinc," she advises.

"Eating things such as cashews, pumpkin seeds, beans, spinach. But if you do eat everything, then having a good amount of seafood is key, salmon, shellfish, red meat once a week, that should be good enough to get in zinc for your immune system.

"If you want to supplement with zinc, just be mindful. Try to have 15 milligrams or less because taking a lot of zinc can trigger nausea and affect our copper status as well. So we don't want to overdo it with zinc," she cautions.

Nic Paton is one of the country's foremost journalists on workplace health, safety and wellbeing, and is editor of Occupational Health & Wellbeing magazine. He also regularly writes on the health and employee benefits and health insurance markets.