The immune system helps protect the body against contagious diseases, such as colds and flu. Diet plays an important role in maintaining a strong immune system. Regular consumption of certain unhealthy foods can prevent the immune system from working properly. This can reduce its ability to perform as well as it could. Some research suggests that diets high in added sugar and excessive salt are associated with an increased risk of certain autoimmune diseases and other chronic diseases.
On the other hand, eating foods that contain certain nutrients, such as vitamin C, can help boost the immune system.

Not all inflammatory or immune diseases, including obesity and type 2 diabetes, are caused by diet alone. Environmental disturbances, medications and genetic predispositions also play a role. This article explores specific foods that can weaken the immune system and others that can help strengthen it.

What foods weaken the immune system?

Anyone looking to support their immune function may want to limit or avoid the following types of foods.

processed foods

Many processed foods contain unhealthy fats, sugars and additives. These can improve a product’s taste, texture and shelf life, but, as the studies below suggest, they can weaken the immune system.

Some processed foods that contain high amounts of additives include the following

– canned foods
– prepared meals
– the chips
– cakes and cookies

A 2017 study found that consuming foods containing additives may increase the risk of several chronic inflammatory or metabolic diseases. The study looked at additives such as sucralose, aspartame, carboxymethylcellulose, polysorbate-80, sodium, and carrageenan. The researchers also observed that people with a diet high in additives are more likely to suffer from obesity, immune system-related inflammation and insulin resistance.

Meanwhile, a 2014 review of studies noted that a high intake of salt, refined sugar, saturated fat, and omega-6 fatty acids, along with a shortage of omega-3 fatty acids , can damage the immune system. Consuming sugars and fats in processed foods could also lead to overconsumption of calories, which may increase the risk of obesity. Obesity can lead to inflammation, which can lead to insulin resistance, as well as immune system dysregulation.

Foods high in sugar

People whose diets are high in sugar are at increased risk for several chronic diseases, including coronary heart disease and type 2 diabetes.

Foods that tend to be high in sugar include:

– preserves, marmalades and sweets
– cookies and cakes
– sweet dairy products
– sugary cereals for breakfast
– sugary drinks, such as sodas

A diet high in sugar can also limit the immune system’s ability to fight disease. This can be done by reducing the efficiency of white blood cells and increasing inflammation.

Foods high in refined carbohydrates

Foods that are processed and high in refined carbohydrates, such as white flour and refined sugar, are associated with increased inflammation and oxidative stress, which can harm the immune system.

Foods that contain refined carbohydrates include the following

– white rice
– white bread
l- sweets, biscuits and cakes made with white flour.

Foods for a Healthy Immune System

A balanced, nutrient-dense diet can help maintain a moderate body weight, which is important for immune system function.

The following foods may provide more specific immune-boosting benefits.

– Citrus fruits

They are good sources of vitamin C, and a 2017 study found that vitamin C has several properties that can contribute to healthy immune function. Vitamin C is a powerful antioxidant. Antioxidants protect important molecules in the body, such as proteins and carbohydrates, from environmental and biological damage. Vitamin C also helps support metabolic energy and hormone regulation, and is necessary for collagen production. The same 2017 study reports that most people should aim to consume 100–200 milligrams (mg) of vitamin C daily.

– Foods that contain zinc

Zinc is an essential mineral that is a key trusted source for maintaining a healthy immune system. The recommended daily intake of zinc varies from 2 to 11 mg, depending on the age and sex of the person. Pregnant women need 11-13 mg.

Here are some food sources of zinc

– oysters
– beef
– beans
– fortified cereals
– chicken breast
– cheese
– peas

– Cruciferous vegetables

These vegetables, including broccoli and broccoli sprouts, are good sources of the compound sulforaphane, which can help boost the immune system. A 2016 study observed that sulforaphane has antioxidant, anti-inflammatory, and anti-cancer properties. A 2018 study looked at the effect of sulforaphane on colon cancer cells. She found that sulforaphane prevented inflammation of immune cells, which the researchers believe could help prevent the development of cancer.

– Ginger

People have been using ginger to add flavor for centuries. More recently, researchers have studied its effects on the immune system. A 2020 review of high-quality studies found that consuming ginger supplements combats inflammation associated with osteoarthritis and rheumatoid arthritis. The analysis also found that ginger supplements helped reduce body weight in people with obesity. This could mean that ginger also indirectly improves immune system health, as obesity is linked to chronic inflammation.


Anh, NH, et al. (2020). Ginger on human health: A comprehensive systemic review of 109 randomized controlled trials.

Arreola, R., et al. (2015). Immunomodulation and anti-inflammatory effects of garlic compounds.

Bessler, H., et al. (2018). Broccoli and human health: Immunomodulatory effect of sulforaphane in a model of colon cancer (Abstract).

Bhardwaj, B., et al. (2016). Death by carbs: Added sugars and refined carbohydrates cause diabetes and cardiovascular disease in Asian Indians.

Childs, CE, et al. (2019). Diet and immune function.

Garcia-Montero, C., et al. (2021). Nutritional components in Western diet versus Mediterranean diet at the gut microbiota-immune system interplay.

Greaney, AJ, et al. (2016). Sulforaphane inhibits multiple inflammasomes through an Nrf2-independent mechanism (Abstract).

Nutrition and immunity. (nd).

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