Immunity and diet: what you need to know

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Dubai Health Authority immunity diet
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In recent weeks, much attention has focused on the role of the immune system and its role in defending against disease-causing microorganisms. While the body has an impressive array of weapons to battle any invaders, there are moments when pathogens bypass these warriors, virus and bacteria sometimes do get through.

In such cases, your first port of call should be a medical professional who can advise on treatment routes.

That said, there are a number of ways to reduce your vulnerability, including enhanced hygiene and other everyday preventive measures. Of course, researchers still don’t know a lot about the intricacies of the immune response — and there really are few scientifically proven direct links between lifestyle and enhanced immune function — but evidence intimates that nutritional deficiencies can weaken our immunity and leave us more susceptible to infections.

The strength of the body’s immune system related to its overall nutritional status.

– Marlene Cornes Marsh, Senior Clinical Dietitian, DHA

“Diet and lifestyle are two of the most critical factors that influence immunity,” explains Mitun De Sarkar, a Dubai-based MD who is Clinical Dietitian at Simply Healthy Foods. “While environmental factors are often not in our control, so our best defence to give our bodies a fighting chance against various virus or bacterial infections is to ensure that we follow good hygiene practices and ensure our diets support our immune system’s health.”

A good thumb rule, she adds, is to get in plenty of fruits and vegetables, ensure proper hydration and stay moving. Exercise has a beneficial impact on the immune system and mobilises white blood cells.

But this is a nutrition column, so we’ll confine ourselves to food’s role in immune health. In particular, people underestimate the importance of good nutritional habits. Marlene Cornes Marsh, Senior Clinical Dietitian at Dubai Health Authority, says a balanced diet, coupled with a healthy lifestyle strengthens your body’s defences against infection. “The strength of the body’s immune system relates to its overall nutritional status,” she says, adding that stress, poor diet and inadequate sleep can also play their part.

“There is scientific evidence to support the adage ‘we are what we eat,’ and this process begins in early life. It is well established that nutritional inadequacy greatly impairs the functioning of immune system. Good nutrition plays an important role in the body’s immune system. It stimulates the formation of antibodies, and with healing and recovery.”

Avoiding undernutrition

On the other hand, undernutrition can have several harmful benefits. As an example, Marsh explains how the thymus, a small organ just beneath the breastbone, is impacted by malnutrition — even the kind caused by obesity.

“People who are on extreme calorie- and protein-restriction diets or who have an eating disorder may see changes in the activity of the thymus gland, which is responsible for the maturation of immune cells,” Marsh says. The thymus helps propagate and differentiate mature T-lymphocytes, cells that attack and kill viruses and bacteria.

Similarly, paying attention to the symbiotic relationship we share with the beneficial microbes that make up the human microbiome, can help fortify our bodies. This collection of microscopic organisms serve several functions. When they’re out of whack, as in older people, the result is stomach inflammation and increased intestinal permeability, which allows more bugs to overcome our defences. But when they’re singing in harmony, so to speak, these microbes function as barrier shields and help encode our immune systems.

Fermented foods and vegetables

The role of fermented foods such have been recognised for more than a century, thanks to the number of beneficial bacteria they contain, De Sarkar says. That’s why items such as yoghurt, sauerkraut, kombucha, kefir and khimchi should be high on your list, she explains.

Similarly, fibre-heavy carbohydrates such as whole grains improve digestion and fuel the body with energy. When it comes to overall health — including immune system function. “Carbs are not your enemy,” she says.

Finally, vegetables really are all they’re cracked up to be. Following a study on mice, Babraham Institute researchers proved how green vegetables such as bok choy and broccoli generate a chemical signal that is important to a fully functioning immune system. They do this by ensuring that immune cells in the gut and the skin known as intra-epithelial lymphocytes (IELs) function properly. When otherwise healthy mice were fed a vegetable-poor diet for two to three weeks, up to 80 per cent of these protective cells disappeared.

Separately, innumerable studies have demonstrated the benefit of antioxidants in vegetables, fruit and other plant-based foods. Nutrients such as beta-carotene, vitamin C and vitamin E not only boost immune health but also help reduce oxidative stress.

While much more research is needed to pinpoint specific interactions, eating healthy has a tremendous number of benefits for the immune system.

As Marsh says, “Almost all nutrients in the diet play a fundamental role in sustaining an optimal immune response, such that deficient and excessive intakes can have negative consequences on immune status and susceptibility to a variety of pathogens.

“Dietary components can regulate physiological functions of the body; interacting with the immune response is one of the most important functions of nutrition.”

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