Building Your Immune System: Daily Essentials
When we think about the nutrients necessary for immune support, it's helpful to consider the immune system as a whole. Strong antioxidant support not only benefits the immune system but also contributes to overall health in many ways. These key nutrients share the common goal of supporting antioxidant activity, but each one also has its specific role in enhancing immune function. Once this nutritional foundation is established, the introduction of targeted nutrients and botanicals can offer additional benefits.
Vitamin A plays a critical role in maintaining a healthy immune function. In fact, the World Health Organization (WHO) promotes vitamin A supplementation as a vital intervention for child survival in developing countries. Vitamin A is involved in regulating the growth and specialization of nearly all cells in the human body, including those of the immune system. It is crucial for the integrity of epithelial and mucosal barriers, which serve as the body's first line of defense against infections.
Research has revealed that infections can lead to a decrease in circulating vitamin A levels, as infection triggers an acute response that reduces the synthesis of retinol-binding protein in the liver. Moreover, infection and fever increase urinary excretion of vitamin A. Consequently, infections can diminish vitamin A status, which, in turn, affects the body's immune response, especially if initial vitamin A levels are inadequate.
The USDA Human Nutrition Research Center reports that nearly 46-50% of Americans do not consume enough vitamin A from their diets. While obtaining beta-carotene from fruits and vegetables is beneficial, the conversion of beta-carotene to vitamin A (retinol) can be unpredictable. Some of the beta-carotene serves as an antioxidant, and proper absorption and conversion to vitamin A require a healthy digestive system and sufficient fat consumption.
Maintaining adequate reserves of and a consistent dietary intake of vitamin A is crucial for supporting a healthy immune response. This partly explains the positive clinical and research outcomes associated with high-dose vitamin A supplementation at the onset of acute infections. However, it's important to note that high-dose vitamin A supplementation is not advisable during pregnancy or for individuals with compromised liver function and should only be administered under medical supervision after a thorough assessment. Daily supplementation with the recommended daily allowance (RDA) of 5000 IU (125 mcg) is considered safe.
There is little debate about the benefits of vitamin C supplementation for optimizing immune function. One key reason is that humans, unlike many animals, cannot synthesize their own vitamin C and must obtain it through their diet. Researchers have found that vitamin C helps increase glutathione levels by neutralizing free radicals, thereby preserving glutathione. Vitamin C also supports the production and function of white blood cells, especially neutrophils, lymphocytes, and phagocytes, which accumulate high concentrations of vitamin C to protect against oxidative damage.
Experts in the field of integrative medicine emphasize the importance of taking vitamin C supplements several times a day to ensure an adequate supply for various reasons, including supporting a healthy immune system. The dynamic flow model, published in the Journal of Orthomolecular Medicine in 2005, suggests that people should ideally maintain a state of dynamic flow by ingesting more vitamin C than they need, distributed in divided doses throughout the day. The excess ascorbate circulates through the body and is eventually excreted in the urine, acting as a reservoir when extra vitamin C is required. This approach aims to restore our physiology to a state similar to animals that still produce their own vitamin C. Integrative practitioners typically recommend a daily maintenance dosage of 500 mg, taken two or three times a day.
We now understand that vitamin D is essential for immune function, and ongoing research continues to shed light on its critical role. The most accurate way to assess an individual's vitamin D status is to measure the level of 25-hydroxyvitamin D in the blood.
Clinical practice has been slower to catch up with research findings when it comes to defining what constitutes an "adequate" vitamin D status. While most clinical laboratories define a wide "normal" range, typically from 30-100 ng/ml, it is now well-established that optimal immune function requires a higher vitamin D status, ideally between 60-100 ng/ml. As a result, many individuals now safely supplement with vitamin D, especially when they cannot spend enough time outdoors in the sun. Common supplementation doses range from 2000-5000 IU (50-125 mcg) of vitamin D daily.
Zinc is known to be crucial for proper immune function, but what many people may not realize is that zinc deficiency is prevalent worldwide and across all age groups. Even marginal zinc deficiency can have a negative impact on immune function, underscoring the importance of zinc repletion before and during illnesses. Despite the presence of sufficient zinc in our food, it is relatively challenging to absorb dietary zinc. Groups at higher risk of zinc deficiency include vegans, vegetarians, children (due to food choices), older adults, and individuals with gastrointestinal issues, which can hinder digestion and absorption. Factors such as fiber and phytates in whole grains, legumes, nuts, and seeds can interfere with zinc absorption, despite these foods being rich in essential nutrients. Soaking these foods before cooking can help reduce phytates and improve mineral absorption. Among meat sources, beef is the best provider of zinc, offering around 8 mg of zinc in a 6-ounce serving. Pork, turkey, and chicken provide roughly half of that amount. Considering that the minimum recommended daily allowance (RDA) for zinc in adults is 15 mg, and taking into account the interference caused by whole grains, legumes, nuts, and seeds, it's possible that many individuals have zinc deficiency. Infections can further deplete zinc levels, making appropriate supplementation important for maintaining robust immune function.
NAC and Glutathione
The importance of maintaining adequate antioxidant status for proper immune function has recently come to the forefront. This includes recognizing the critical role of the master antioxidant glutathione, which can be depleted, especially during illness. The significance of glutathione in preserving normal cell function cannot be overstated. Scientific research and clinical observations have highlighted the importance of replenishing and maintaining glutathione to support overall health.
Strategies for glutathione repletion include using glutathione precursors like N-acetyl cysteine (NAC) and whey protein, which also provide cysteine in the oxidized form known as cystine. Studies are ongoing to assess the absorption and impact of supplementation with liposomal glutathione.
NAC, in addition to supporting glutathione replenishment, exhibits antioxidant activity and mechanisms that support the immune system. Therefore, it's important to consider NAC as a foundational nutrient for immune support.
Probiotics and Prebiotics
We are aware that many types of Lactobacilli and Bifidobacteria positively impact the immune system, both directly and indirectly. A robust and balanced microbiome is key to a strong, healthy immune system, and probiotics are now considered just as essential as a multivitamin. Furthermore, prebiotics, often referred to as "microbiome-superfoods," can enhance the immune-supporting capabilities of the microbiome. Over the past two decades, research has consistently shown that arabinogalactan, a prebiotic fiber found in larch trees and echinacea, has a beneficial effect on the immune system. It enhances the activity of natural killer (NK) cells and macrophages, boosts the complement system, and promotes the production of inflammatory cytokines. While some of this effect is attributed to the production of healthy short-chain fatty acids through the fermentation of arabinogalactan by gut bacteria, ongoing research aims to uncover even more direct influences and mechanisms.
Botanical Support: Mushrooms, Beta Glucans, Olive Leaf, Astragalus, and Elderberry
For centuries, mushrooms have been utilized to bolster immune health. Their immune-supportive effects are, in part, attributed to the potent polysaccharides called beta glucans. Both mushroom and yeast-derived beta glucans, like Wellmune, are known to enhance the function of natural killer (NK) cells and macrophages, vital components of the immune system. Additionally, mushrooms are rich in antioxidant compounds, proteins, phenolics, and indolic compounds.
Numerous studies have highlighted mushrooms' potential to support immune function and maintain a healthy inflammatory response. Research has shown that mushrooms can positively influence cytokine production, as well as the functioning of T-cells and natural killer cells. Compounds found in mushrooms have also been observed to aid in the development and activity of lymphocytes and macrophages.
A 2018 review sheds light on the molecular impact of mushrooms on signaling pathways like PI3K/AKT, Wnt-CTNNB1, and NF-κB, with some mushroom compounds targeting specific nodes in these pathways.
According to a 2017 review in the International Journal of Medicinal Mushrooms, mushrooms contain various bioactive polysaccharides and polysaccharide-protein complexes that influence both innate and cell-mediated immune responses. Over 600 studies worldwide and numerous human clinical trials have provided substantial evidence of the benefits of medicinal mushrooms.
Immune-supporting mushroom extracts are available as standalone ingredients or as part of comprehensive immune system formulations, making them an indispensable component of immune support.
In April 2020, a study published in The Journal of the American College of Cardiology underscored the connection between higher olive oil intake and heart health, as well as a balanced inflammatory response. While the benefits of olive oil in daily nutrition are well known, botanical experts also recognize the significance of the polyphenols it contains.
Olive leaves, in fact, contain higher concentrations of polyphenols compared to the fruit and have been traditionally employed for cardiovascular and immune support. Olive Leaf Extract comprises oleuropeins, which exhibit antioxidant properties and offer support for vascular health and the immune system. Additionally, olive leaf extract contributes to the maintenance of a balanced cytokine profile, playing a crucial role in regulating the body's immune and inflammatory responses. Evidence suggests that olive leaf extract promotes the production of nitric oxide (NO)
, thereby benefiting blood vessels. Its multifaceted actions on both the immune and vascular systems make olive leaf extract a top choice for daily immune support.
Astragalus membranaceus, also known as Huang-qi, is highly regarded in Traditional Chinese Medicine and is widely recognized for its adaptogenic properties and immune support in western herbal traditions.
Research conducted on mice, chickens, and pigs has demonstrated astragalus' positive impact on immune function. Human clinical trials have revealed that the polysaccharides, flavonoids, and saponins in astragalus support immune health by activating toll-like receptor 4 (TLR4)-related mitogen-activated protein kinase (MAPK) activities.
A 2009 review and meta-analysis of 45 randomized clinical trials with active control groups indicated that astragalus has immunomodulatory properties that enhance T-cell function. A 2010 meta-analysis of 65 clinical trials with nearly 4,800 patients confirmed the effectiveness of astragalus in supporting immune health.
Elderberry syrup is a well-known remedy for immune support, and its effectiveness is supported by modern scientific research. Elderberry's high biological activity is attributed to phenolic compounds such as quercetin, rutin, kaempferol, and anthocyanins, the mechanisms of which are still being studied. Notably, quercetin, present in elderberry, acts as a zinc ionophore, facilitating the delivery of zinc into cells—an essential element for immune function.
Elderberry's rich color comes from anthocyanins, which become incorporated into cell membranes and cytosol, exerting potent antioxidant effects. These antioxidants counteract oxidative stress, boost the activity of antioxidant enzymes in the blood, and increase glutathione production—all crucial processes for optimal immune system function. Reducing oxidative DNA damage is another benefit of elderberry's high antioxidant activity.
Elderberries also support the immune complement system, enhancing its activity. Studies have shown that elderberry extracts have complement-fixating properties.
In February 2019, a meta-analysis of randomized controlled clinical trials, involving 180 participants, was published in Complementary Therapies in Medicine, concluding that elderberry substantially supports immune status. While elderberry syrup is popular, more concentrated forms are available in liquid extracts or capsules.
These nutrients and botanicals are valuable daily additions to any health regimen. As we delve deeper into their mechanisms of action, we discover that they not only offer immune system support and balance but also provide cellular support for the cardiovascular, circulatory, gastrointestinal, neurological, and dermatological systems, among others.