Overview

Croup, an infectious lung disease occurring in children, can be a scary experience for a parent and the affected child. A diet that boosts the immune system can reduce a child’s risk from developing croup. Immune-boosting diets can support overall health, wellness, and disease prevention, not just croup.

What is croup?

As alluded to above, croup is an infectious disease of the respiratory tract. The upper airway constricts and makes breathing difficult, leading to a “barking” cough and noisy, “whistling” breaths. Treatment can usually be managed at home. However, since immune-boosting diets are known to help prevent croup, they are worth investigating and implementing.

Role of diet in immune health

Importance of boosting the immune system

Most cases of recurrent croup are caused by a virus. Since viruses cannot be easily treated with medication, parents can focus on the prevention of croup if they know their child is more likely to develop it. Increasing the immune system's ability to fight infections makes it more likely that the bacteria or virus will be eliminated before full-blown symptoms develop.

Key nutrients to support the immune system

Several different mechanisms can be identified when looking at foods and nutrients that boost the immune system. Some help generate and activate cells that take part in the immune response, some reduce inflammation, and some increase the health of the microbes in our guts.

Vitamins

Consuming an appropriate amount of vitamins every day has been shown to help boost immunity and ensure proper immune function.¹ Vitamin deficiencies can lead to a compromised immune system and increased illness. Several vitamins are crucial to a well-functioning immune system such as:

• Vitamin C - antimicrobial; helps regulate the immune system¹
• Vitamin D - decreases inflammation; increases activity of immune cells; slows replication of viruses¹
• Vitamin A - boosts the ability of the skin to protect against invaders¹
• Vitamin B6 - helps the immune system produce T-cells (a type of immune cell) and antibodies²
• Vitamin B12 - increases immune system clean-up¹
• Vitamin E - increases the action of another immune system cell (Natural Killer cells)¹
• Vitamin K - reduces inflammation and works with some proteins crucial to the immune response³
• Vitamin B9 (folate) - increases the number of T-cells in the immune system¹

Minerals

Like vitamins, minerals have a direct impact on the functioning of the immune system.

• Copper - optimises the immune response¹
• Iodine - increases production of antibodies; better “clean up” by the immune system
• Iron - regulation and proliferation of immune system cells especially in the gut
• Magnesium - anti-inflammatory; helps with cellular stress; boosts immune function¹
• Selenium - antioxidant; supports the development and function of T-cells and Natural Killer cells¹
• Zinc - anti-inflammatory; antimicrobial; necessary for cellular function

Omega-3 fatty acids

These compounds are present in fish oil and flaxseed. Omega-3 fatty acids come in several different varieties, but they all help build and preserve cell membranes and produce important molecules involved in cell signaling of the immune system. Inflammation can also be down-regulated if an individual takes in enough omega-3. There are three key types of omega-3. Typically, people consume more than enough alpha-linoleic acid but not enough docosahexaenoic acid and eicosapentaenoic acid.¹ In this case, it is recommended to take a supplement to ensure adequate amounts.

Probiotics and prebiotics

Probiotics and prebiotics relate directly to the microbial population found in the intestines. Since 70-80% of the immune system is in the gut, gut health is critical to have an optimally functioning immune system.⁵ Prebiotics provide  fibres and simple sugars to feed the gut bacteria while probiotics contain healthy bacteria, and by eating probiotic-rich foods, the gut microbiome can be improved therefore improving overall immune health, in addition to other bodily systems. 

What is an immune-boosting diet?

Food is full of nutrients. In addition to protein, fat, and carbohydrates, vitamins and minerals are found in differing amounts depending on the type of food. While some people may first reach for a vitamin supplement, the immune-boosting nutrients found in food are typically more available to the body and more effective. In addition, if someone is getting their vitamins and minerals through healthy whole foods, such as fruits and vegetables, they do not need to worry about the extra nutrients that may be in a supplement. There may not necessarily be a specific formula for an immune-boosting diet; however, there are specific food items that should be increased and items that should be decreased to help the immune system be more active. Water is also a key part of an immune-boosting diet.

Foods that increase immune system activity

• Fruits
• Vegetables
• Whole grains
• Probiotic foods (like kefir, yoghourt, sauerkraut, and other fermented foods)
• Prebiotic foods (found in garlic, onion, bananas, seaweed, and several other foods)

Foods that decrease immune system activity

• Added sugars
• Ultra-processed foods - added flavours, colours, preservatives, sweeteners, etc which are commonly found in packaged chips, cookies, sugary drinks, lunch meats, etc.

Implementing an immune-boosting diet for croup

Incorporating immune-boosting foods

Based on the information above, foods that help to optimise the functioning of the immune system can be separated into a few key categories. These include fruits and vegetables, lean protein, whole grain products (breads, pastas, cereals, etc), Omega-3 fats, probiotic foods, and foods containing prebiotics. Several specific ways of eating include these various food groups, including the Mediterranean diet, whole food diets, and even vegetarian or vegan diets. These specific eating patterns also discourage added sugars and other ingredients found in ultra-processed foods. Designing a meal plan to boost immunity for either an adult or child, which would be more relevant in the case of croup, can be accomplished by putting together the information listed above.

Sample meal plan

Breakfast

• Scrambled eggs - protein, vitamin D, and Omega-3
• Side of sauteed greens (kale or spinach) - vitamin A and E
• Orange - vitamin C
• Green tea/ green tea latte - antioxidants

Lunch

• Tempeh - probiotic
• Avocado - vitamin E
• Sweet potato - vitamin A
• Black beans - zinc

Supper

• Turkey cooked in garlic - zinc and vitamin B6
• Stir-fried red peppers - vitamin C
• Cantaloupe - vitamin A
• Yoghourt with some added flaxseeds and chia seeds - probiotics and omega-3

Snacks

If you choose to have a snack during the day,  the best options would be whole foods such as fruits, vegetables, or legumes. Items with added sugars or those that are highly processed are known to lessen the immune response. Additionally, overall health can be improved by opting for a healthy, natural choice when a snack is needed.

The importance of hydration

Water is important to sustain life. In fact, the human body is approximately 50-60 percent water and adequate daily intake is important for many reasons including immune function. Water is utilised in many ways throughout the body. The main method by which we take in water is through our digestive tract. 

Regarding the immune system, the main way in which water increases the immune system’s function is by creating more lymphatic fluid which transports immune cells throughout the body. With an appropriate water intake, adequate amounts of lymph can be made and cells of the immune system can travel to where they need to go. This means that the immune system may find viruses, bacteria, fungi, or other microbes sooner than if the lymph fluid was at a lower level. 

Water should be consumed throughout the day, with a  recommended daily intake  of at least 11.5 cups (2.72 litres) for a biological adult female and 15.5 cups (3.67 litres) for a biological adult male. In addition to drinking water, water-rich foods can also increase total water intake. These include watermelon, cucumbers, and celery. Not only do these increase water content in the body, but they each contain key vitamins which are beneficial for immune functioning. 

Since croup is typically more often seen in childhood, it is important to note that the recommended daily water intake differs for children. The amount is based on age.

• 0.5-1 cup per day (0.12-0.24 litres): six months to one-year-old
• 1-4 cups per day (0.24-0.95 litres): one to two years old
• 1-5 cups per day (0.24- 1.18 litres): two to five years old

Summary

Immune-boosting diets are a relatively new concept in the worlds of nutrition and health but they can be incredibly beneficial to anyone who follows this style of eating. Taking in adequate foods containing necessary vitamins and minerals decreases the need for supplements which typically cannot be guaranteed for their concentration and effectiveness. Prebiotics and probiotics help to colonise and feed the gut’s microbiome with healthy gut flora, which in turn leads to better gut health, immunity, and overall well-being. Simple whole foods and adequate water can have a great impact on immune function. They can be a valuable tool to prevent infection and preserve health.