Reboot the Immune System

Is it really possible to boost our immune system? What if we make lifestyle choices like improving our diet or take certain vitamins or herbals? We’ve discussed how incredibly complex the immune system is, and how in order for it to function well, it requires balance in all of its intricate systems. Stress reduction and healthy living strategies such as eating nutritiously, maintaining a healthy weight, exercising regularly, drinking alcohol in moderation, stopping smoking, and getting adequate sleep are all natural ways to keep our immune system healthy.

At the first signs of cold symptoms such as a sore throat or generalized achiness, many people reach for well known items such as Vitamin C, echinacea, and zinc lozenges. While it’s important to follow a healthy diet rich in nutrients, even those whom we might think eats a clean diet may not be consuming a proper balance, or someone with a GI issue may not be absorbing the nutrients properly.  Demonstrating whether a substance actually enhances immunity is a very complicated matter, but there is much research that links many substances and their benefits for overall immunity.

Let’s discuss a few of the most common substances in deeper detail to get into the science behind how they work to bolster our immune system.

Zinc

Zinc is one of the most abundant minerals in our body, second only to iron. It is an essential trace element that is needed to support normal growth such as dividing cells, making proteins and DNA, as well as supporting healthy skin by healing wounds and assisting to keep our immune system strong.^[1]

Zinc is called “essential” because we need to get enough of it daily through our diet as our body can’t store it. The Recommended Dietary Allowance (RDA) for adults is 8 mg/ day for women and 11 mg/day for men.^[2] The Tolerable Upper Intake Level (UL) for adults is 40 mg/day. While most North American diets provide the recommended dietary allowance via foods like red meat, poultry and seafood, some demographics may have subclinical zinc deficiency that they are not aware of. Individuals with digestive malabsorption disorders such as Ulcerative Colitis, Crohn’s Disease and untreated or unknown Celiac Disease can have decreased zinc absorption.^[3] Many alcoholics are fundamentally malnourished with micronutrient deficiencies as they tend to decrease their food intake or quality of food intake in lieu of alcohol. It should be noted that while legumes and whole grains are foods that contain zinc, the zinc is less bioavailable to the body, so vegetarians and vegans can be susceptible to zinc deficiency.^[4]

So how does zinc actually work to bolster our immune system? Here’s some info for you science geeks.😉

The body needs zinc to develop and activate T-cells, and even mild zinc deficiency can weaken some white blood cell functions.^[6] Zinc not only helps produce these substances that help in the immune response but also stops their production when they’re no longer needed.^[7] In this way zinc acts with a feedback loop, or “on-off” switch in the immune system by slowing down the immune response and limiting the amount of inflammation once the initial response has been mounted. While we want a robust inflammatory response to defend us against an invading pathogen, too much inflammation attacks not only the pathogen but can also cause much more collateral damage. Zinc deficiency then, impairs not only the first responder functions, but also decreases the ability of the body to stop the inflammatory pathway once it has begun.^[8]

While recent research is showing that there are many benefits to zinc supplementation to boost our immune system, too much zinc can be detrimental, and supplementation should be carried out with caution. Reciprocally, an overabundance of zinc has been found to depress immune function, potentially reducing the number of T-cells with resultant decreased ability of the body to fight infections.^[9] High zinc intake can also inhibit copper absorption, which in turn can alter iron function, resulting in anemia.^[10]

Vitamin D

Vitamin D is a fat-soluble vitamin that plays an enormous role in numerous processes in our body. One of its main roles is to help absorption of calcium to occur and also regulate our blood calcium and phosphate concentrations^[11] This is key for bone mineralization as well as growth and remodeling by osteoblasts and osteoclasts. Vitamin D is also involved in other things such as cell growth, neuromuscular function, and immune function.^[12]

Vitamin D is often called “the sunshine vitamin” because we produce it when we expose our skin to sunlight (UVB). We can make all of the vitamin D we need if exposure to sunlight is optimal and liver and kidney function are normal.^[13] Because Vitamin D is “activated” in our body by our kidneys and liver, if we have kidney or liver disease our activation will be impaired. Vitamin D is actually classified as a hormone because it’s synthesized in our skin and has function elsewhere. We actually have Vitamin D receptors in our bones, small and large intestines, our brain, and our immune cells.^[14]

Regarding immunity, Vitamin D research has shown that B-cells and T-cells have Vitamin D receptors that use Vitamin D to make enzymes that help to fight infection in a variety of ways^{[15] [16]}

To achieve optimal Vitamin D levels with the sun alone, one must have full sunlight exposure with minimal clothing and no sunscreen during the middle of the day for an extended period of time. Ultimately, many people can’t achieve therapeutic Vitamin D levels with the sun alone because of medical issues such as with the kidneys and liver as discussed, but also due to geographical location, lifestyle choices, or seasonal changes.^[17]

Melanin in the skin can reduce the effectiveness of sunlight producing Vitamin D, which is why people with darker skin have been documented to have lower Vitamin D levels, even if they live in temperate climates.^[19] In the Northern Hemisphere between the months of October and April, the suns rays are not strong enough to synthesize Vitamin D on our skin. Deficiency of Vitamin D can occur when sunlight exposure is decreased due to these environmental factors, as well as cultural clothing customs concealing our body, or the inability of older adults or people with disabilities to get outdoors. In addition, as we get older, we cannot synthesize as much Vitamin D due to aging skin changes.^[20] The fact that most people’s Vitamin D levels are lowest in the winter suggests a possible link to the increased occurrence of infections during wintertime. Vitamin D is widely researched, and there are many studies that show low Vitamin D levels are associated with respiratory tract infections such as cold and flu^[21], inflammatory conditions such as allergies and asthma,^[22] inflammatory bowel disease (IBD)^[23], chronic pain conditions^[24]and autoimmune disorders such as multiple sclerosis.^[25]

The most common form of Vitamin D in the diet and supplements is D3 (cholecalciferol). A wide “optimal” range for Vitamin D blood levels is reported (25-80 ng/mL), and differences of opinion exist as to what deficiencies are defined as.^[26] In general, scientific literature and health experts assert that 50 ng/ml is the optimal serum Vitamin D level we should all strive for to support our health and well-being.^[27]

While the maximum safe dosage of Vitamin D remains disputed, North America’s current tolerable upper intake level is 2000 IU (50 µg) per day in North America; however, some scientists recommend an increase to 5,000 IU per day.^{[28] [29]} It actually takes 100 IU of Vitamin D to increase a normal-weight adult’s serum D levels by about 10 ng/ml, so to achieve optimal levels of 50 ng/ml, a person would need 5000iu per day.^[30]

Not many foods naturally contain Vitamin D. The flesh of fatty fish such as trout and salmon are among the best sources. Small amounts of Vitamin D can be found in beef liver, cheese, and egg yolks. As a comparison, a serving of trout provides 645iu while 1.5 ounces of cheddar cheese provides 17iu.^[31] In general, fortified milk has 100iu per cup, and it can also be found in some orange juices and ready-to-eat cereals.^[32] Achieving high levels through diet alone would be very difficult. Research in 2017 illustrated that daily Vitamin D supplementation could help prevent colds and flu, especially in those people who were deficient in Vitamin D.^[33] A different study focused on Vitamin D-deficient participants, found that Vitamin D supplementation can decrease viral respiratory infection by 70%.^[34] Since Vitamin D is a fat soluble vitamin, it gets stored in our body, so extreme supplementation must be used with caution..

Vitamin C

Is Vitamin C your go-to when the sniffles come?

Vitamin C, or ascorbic acid, is an essential water-soluble vitamin, so it must be taken daily via food or supplements. Vitamin C is mostly found in fruits such as citrus fruits and strawberries, and vegetables such as red and green peppers, tomatoes, potatoes, broccoli, and other green leafy vegetables.^[35] At-risk groups for Vitamin C deficiency include chronic alcohol and drug users, smokers, those with some gastrointestinal diseases and some cancers, and of course individuals with inadequate dietary intakes of fruits and vegetables.^[36]

Vitamin C is necessary for collagen formation for our bone matrix, teeth, cartilage, skin, and connective tissue.^[37]Thus, Vitamin C is integral to wound healing as it is vital for the growth and repair of body tissues. ^[38]

Vitamin C acts as a powerful antioxidant with versatile anti-inflammatory properties.^[39] Antioxidants protect our cells from harmful free radicals that promote oxidative stress.^[40] Oxidative stress has been associated with many chronic diseases, and research has illustrated that ingesting Vitamin C can increase blood antioxidant levels, helping the body fight inflammation.^{[41] [42]}One study did an analysis of 9 different studies, indicating that over a 10 year period, people who took 700mg of Vitamin C daily had a 25% lower risk of heart disease than those didn’t take a supplement.^[43] Another research analysis showed that Vitamin C supplementation lowers low-density lipoproteins (LDL) – the “bad” cholesterol – and triglycerides.^[44]

Vitamin C is well known for its integral role in supporting a strong immune system.^[45] Vitamin C enhances epithelial barrier functions, thereby strengthening our first line of defense against invading pathogens.^[46] Vitamin C also appears to potentiate many important aspects of neutrophil function.^[47] Some research has shown that Vitamin C supplements might even shorten how long a person has the common cold in addition to decreasing the severity of symptoms.^{[48] [49]}

To provide antioxidant protection, 90 mg/day for adult men and 75 mg/day for adult women is recommended for those in optimal health.^[50] Others are recommended to increase their daily intake.

The Tolerable Upper Intake Level (UL) for adults is set at 2 g/day, as gastrointestinal disturbances such as diarrhea can occur for some people above these levels.^[51]

It is important to note that while Vitamin C deficiency results in impaired immunity and higher susceptibility to infections, when someone has an active infection, inflammation, or wounds, Vitamin C levels are significantly impacted due to increased metabolic requirements for healing.  Thus a person who has increased metabolic demand would need higher doses of Vitamin C overall.^[52]

Vitamin A

The effects of Vitamin A on our bodies aren’t generally well known by many people. Some people know that it’s imperative for your vision, or that if you use it topically (Retin-A) it can help acne and wrinkles, but did you know that it is crucial for the immune system? Vitamin A plays a critical role in enhancing immune function and helping the antibody response.^[53]  Vitamin A is also known as an anti-inflammatory vitamin, promoting cell growth and differentiation, and protecting epithelium and mucus integrity in the body.^[54] We know that the gut is the foundation of our immune system, so Vitamin A plays a huge part in maintaining its integrity and mucosal defenses as well as keeping inflammation in check.

Vitamin A is a fat-soluble vitamin, thus the body stores excess amounts, mostly in the liver. This means that excess Vitamin A supplementation can have significant toxic ramifications, most notably for the liver. Vitamin A deficiency is rarely seen in developed countries, but is common in developing countries.^[55] Vitamin A is found in many foods such as eggs, dairy products, and organ meats such as liver. Other sources are foods rich in beta-carotene (provitamin A), the nutrient that is converted to Vitamin A in our bodies, such as green leafy vegetables and orange and yellow vegetables and fruits.

Herbals

There are two herbals worth mentioning due to their significant antiviral and antibacterial properties that are well documented in science.

Black elderberry (sambucus nigra), is one of the most commonly used medicinal plants in the world, and traditionally, Indigenous people used it to treat colds, fever and rheumatism.^[56]  Elderberry has demonstrated potent antibacterial and antiviral potential against bacterial upper respiratory infections as well as the influenza virus.^{[57] [58] [59]}

Echinacea, mainly the E. purpurea species, has been used for centuries to treat respiratory tract infections and inflammatory conditions.^[60] Echinacea has been shown in research to reduce the duration and severity of cold symptoms.^[61] Research has also illustrated the anti-inflammatory, anti-viral and anti-bacterial effects of echinacea.^[62]

So there you have it! You’ve learned a lot about your immune system, it’s connection to stress, and your ability to bolster it through healthy living and natural means. Take this knowledge to heart, and tie it in with the information to follow. Your body will thank you!