6 Common Immune-Boosting Supplements

Boost or bust? The truth about common supplements taken during flu season 

Written by Liana Greenshields, Student in the Dietetics Specialization program at the University of Alberta and reviewed by our Health Stand Nutrition Dietitian Team.

As the cold and flu season approaches, many of us may turn to various remedies in hopes of warding off illness or shortening the duration of our symptoms. Among these remedies include supplements, which are popular for their potential to boost our immune systems and provide relief. However, despite their popularity, these supplements are not always the go-to choice for preventing and treating the cold and flu. 

In this blog post, we’ll explore six common immune boosting supplements that many people rely on during flu season to, discuss their effectiveness based on current research, and explore why they might not be as reliable as we hope. Understanding the limitations of these supplements can help us make more informed decisions about staying healthy during the flu season. 

Vitamin C

What is it? 

Vitamin C is a water-soluble vitamin found in many fruits and vegetables, such as oranges, peppers, grapefruit, and kiwis. It is required for the body to synthesize collagen, the main protein in connective tissue, as well as bone formation and wound healing. The reason vitamin C is marketed as an immune-enhancing supplement is because of its role as an antioxidant, which helps protect cells from free radicals that can cause damage. 

Vitamin C was first proposed as a treatment and prevention for the common cold in the 1970s by chemist and biochemist Linus Pauling. He suggested that its antioxidant activity helped to protect and strengthen the immune system to reduce the incidence of the common cold. Since then, there have been numerous studies looking at these effects.

Can vitamin C help strengthen the immune system? 

The consensus is that taking a vitamin C supplement every day does not prevent colds, and only slightly shortens the amount of time that one is ill. In addition, taking a vitamin C supplement after cold symptoms have already started does not treat or manage cold symptoms. 

Should I take a vitamin C supplement? 

It is recommended that adult men and women consume 90 mg and 75 mg per day, respectively. This is the equivalent to eating one red pepper or one orange, so it’s quite easy to meet the recommended intake. If you consume more than this amount, your kidneys will filter it out and get rid of the extra in the urine. Most supplements provide 500-1000 mg of vitamin C, so the majority of it will leave your body through urine. 

Therefore, if you are okay with having “expensive pee” or don’t consume vitamin C-rich foods often, a supplement may help you meet your needs. But, it’s not necessarily recommended to help prevent a cold, as the evidence is lacking. 

Echinacea 

What is it? 

Echinacea, also known as coneflower, is a flower in the daisy family found in eastern and central North America. It is commonly marketed as a supplement to prevent colds and flu with the idea that it stimulates the immune system to fight infections more effectively. 

Can it help strengthen the immune system? 

There have been many studies looking at the effects of Echinacea in preventing and treating colds. However, the main findings suggest that Echinacea products do not treat or prevent colds. 

Should I take an Echinacea supplement? 

Taking an Echinacea supplement is up to you, however, before taking any herbal supplement, you should consult with a healthcare professional. Herbal supplements can interact with other medications, compromising their effectiveness and, therefore, your health. They can also cause some direct effects, such as nausea, diarrhea, constipation, and vomiting. 

Zinc Lozenges 

What is it? 

Zinc lozenges are said to help shorten colds and make symptoms less severe. Instructions suggest taking up to 5 a day at the first signs of a cold. They are also marketed as immune-enhancing supplements. 

Can it help strengthen the immune system? 

This seems to be a common trend so far in this post, but zinc lozenges have not been proven to be effective in treating or preventing the common cold in everyone. While some studies have shown that taking zinc lozenges may shorten cold symptoms by about one 1 day, the evidence is very inconsistent across studies, meaning there is no definitive evidence to suggest that zinc lozenges are effective immune-boosting supplements or to prevent a cold. A randomised, double-blinded, placebo-controlled trial looked at 87 individuals who contracted the cold and took a zinc lozenge 6 times per day for 5 days. In this study, they found no evidence that the lozenges had any effect on their cold. This seems to be a common trend among other studies.

Should I take a zinc lozenge? 

The recommended amount of zinc for adult men and women is 11 mg and 8 mg per day, respectively. Zinc lozenges provide 10-14 mg of zinc, but are instructed to be taken 5 times a day, giving much more than the recommended daily amount. Some side effects are heartburn, upset stomach, and metallic taste in the mouth. They may also interact with other medications. Therefore, it is recommended to talk to your healthcare provider before choosing to take a zinc lozenge. 

Ginseng 

What is it? 

Ginseng is a plant that is commonly sold as an immune-boosting supplement. It has been used as an herbal medicine in Asia and North America for many centuries and is also marketed to treat and prevent the common cold.

Can it help strengthen the immune system? 

While some studies have shown that it can prevent the onset of a cold, the results are inconsistent, meaning the evidence is not strong and it cannot be definitively suggested as a supplement to prevent colds and flu.

Should I take a ginseng supplement? 

Much like Echinacea, ginseng is an herbal supplement that can interact with other medications and compromise their effectiveness. They can also cause headaches, dizziness, upset stomach, and allergic reactions. Therefore, before taking a ginseng supplement, talk with your healthcare provider. 

Elderberry 

What is it? 

Elderberry is a plant, and is one of the most commonly used medicinal plants in the world as a possible supplement to enhance the immune system and prevent colds and flu.

Can it help strengthen the immune system? 

There have been only a small number of studies on elderberry as a supplement to prevent colds and flu, in which the evidence is inconclusive. Altogether, there is not enough evidence to support elderberry as a treatment or preventative measure for colds and flu.

Should I take an elderberry supplement? 

A common trend amongst these supplements, is that elderberry is also an herbal supplement that can interact with other medications and cause the symptoms already listed above. Therefore, before taking a ginseng supplement, talk with your healthcare provider. 

Probiotics 

What is it? 

Probiotics are live bacteria that can have beneficial effects on the body, especially the gut. They can be found in the form of a pill, but certain foods such as yogurt and kimchi also contain live beneficial bacteria. They can help defend against the bad bacteria, which may entice those suffering from a cold or wishing to prevent a cold.

Can it help strengthen the immune system? 

While some studies show that probiotic supplements can help reduce the severity and frequency of colds and flu, this evidence is inconsistent among all studies. Unfortunately, there is weak evidence to support that probiotics can help prevent or treat a cold or flu.

Should I take a probiotic supplement? 

Probiotics can help play a role in maintaining gastrointestinal health, such as helping manage symptoms caused by lactose intolerance, antibiotic-associated diarrhea, and infectious diarrhea, therefore they can be beneficial for health. Always talk with your healthcare provider before taking a supplement, but consider adding some fermented foods to your diet if you want to increase your intake of probiotics. 

Most immune boosting supplements on the market are not supported with strong evidence, and are also relatively expensive. That being said, if you are okay with spending the extra money on supplements, they likely won’t do much harm if you consult with a healthcare professional beforehand. 

Ultimately, the best protection against the seasonal flu is to eat well, get sufficient sleep and get the flu shot every year. As my mom, a pharmacist, always told me: a cold without medication or supplements lasts 2 weeks, while a cold WITH medication or supplements lasts 14 days! 

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