 ’Tis the season…for the sniffles. Cold and flu viruses are all around us. If you do catch one of them, it’s helpful to understand your symptoms and know when you’re most contagious—so you can avoid sharing the bugs with those around you. Is it just a cold, or is it the flu? Sometimes it can be hard to tell. While both the common cold and the flu are respiratory illnesses, they are caused by different viruses.1 But because symptoms are similar, it may take a little detective work to determine which of these is ailing you. Cold Approximately one billion Americans catch colds each year.2 Symptoms show up gradually and often begin with a sore throat that is later accompanied by congestion (stuffy or runny nose), headaches, and general malaise. With rest and TLC, a cold may ease up within a week.3 Flu While the same feelings of stuffiness may occur, the flu is characterized by the sudden onset of fever, aches and chills, dry cough, and extreme fatigue.4 Unlike colds, the flu can give way to secondary bacterial infections, pneumonia, and other risks,1 so it’s important to take time off and get the rest your body needs to recover. Both children and elderly people are at an increased risk of catching the flu due to lower immunity.1  Stages of illness
Your body goes through several stages when you become ill with a respiratory virus. First, it undergoes a period of incubation (1-2 days) when it is first exposed to the organism. As the virus takes over, onset occurs and symptoms show up—letting you know that you’re unwell. While the flu may hit suddenly, you may detect less obvious signs that you’re coming down with a cold, such as a funny feeling in your throat or feeling tired. As the illness progresses, symptoms may worsen before your body recovers and begins to heal itself. When am I contagious? You are most contagious during the incubation period—before symptoms even start. For both cold and flu, this can persist for several days after you’ve begun to feel sick.4 That’s why allowing yourself adequate downtime early on is so necessary. Cold and flu germs can spread very easily. When you sneeze or cough, germs are expelled through the air and may land on other surfaces or objects, where they can survive for several hours. Touching objects or surfaces with germ-laden fingers carries a big risk for those around you, as they may pick up those germs and become infected.4 To spare friends, family, or coworkers of a similar fate, it’s best to stay home and give your body plenty of recovery time. Staying well No one likes getting sick. Whether there’s a cold or flu floating around your household or office, there are ways to be proactive about your health. If you catch something, do yourself and others a favor by staying home and getting some much-needed rest. If your illness persists or shows excessive symptoms, contact your healthcare practitioner. This information is for educational purposes only. This content is not intended as a substitute for professional medical advice, diagnosis, or treatment. Individuals should always consult with their healthcare professional for advice on medical issues. References:
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 by Erik Lundquist, MD
Looking for ways to support healthy immune function? Erik Lundquist, MD shared a variety of options to consider as ways to help support immune health. Here are some formula recommendations he gives to his patients: Vitamins:
Keeping clean & healthy Maintaining good hygiene helps keep the immune system healthy. Consider these simple preventative measures that should be followed routinely to ensure good hygiene practices.
References:
 By Molly Knudsen, MS, RDN There’s no doubt that antioxidants are good for health. Antioxidants have been in the public spotlight since the 1990s and have only gained attention over the years, basically reaching celebrity status. And that status has not wavered, especially as their role in immune health becomes increasingly known. Antioxidants and antioxidant-rich foods continue to trend and make headlines, most recently in the forms of matcha/green tea drinks, acai bowls, golden milk, or just good ol’ fashioned fresh fruits and vegetables. Antioxidants are here to stay not only because they’re found in delicious foods, but they also play a vital role in health by protecting the body against oxidative stress.1 What is oxidative stress? Everyone’s heard of oxidative stress, but what exactly does that refer to? Oxidative stress occurs from damage caused by free radicals. Free radicals are unstable molecules that have lost an electron from either normal body processes like metabolism, reactions due to exercise, or from external sources like cigarette smoke, pollutants, or radiation.1 Now electrons don’t like to be alone. They like to be in pairs. So do free radicals suck it up and leave one of their electrons unpaired? Nope. They steal an electron from another healthy molecule, turning that molecule into another free radical and, if excessive, wreak havoc in the body and its defense system. Immune cells are particularly vulnerable to oxidative stress because of the type of fat (polyunsaturated) that they have in their membrane.2 So high amounts of oxidative stress over time can be especially detrimental to immune system. What are antioxidants? Antioxidants are the heroes that can break this cycle. And there’s not just one antioxidant. Antioxidants refer to a whole class of molecules (including certain vitamins, minerals, compounds found in plants, and some compounds formed in the body) that share the same goal of protecting the body and the immune system against oxidative stress.2 But different foods contain different antioxidants, and each antioxidant has its own unique way of supporting that goal. 6 antioxidants for oxidative stress protection + immune health 1. Vitamin C Vitamin C is a powerful antioxidant that also contributes to immunity. It works by readily giving up one of its electrons to free radicals, thereby protecting important molecules like proteins, fats, and carbohydrates from damage.3 Vitamin C is a water-soluble vitamin, which means storage in the body is limited, and consistent intake of this nutrient is vital. Research shows that not getting enough vitamin C can impact immunity by weakening the body’s defense system.3 Vitamin C is found in many fruits and vegetables, including strawberries, bell peppers, citrus, kiwi, and broccoli. The benefits of vitamin C’s antioxidant capabilities are more than just internal. Benefits are also seen when a concentrated source of this antioxidant is applied to the skin. For example, topical vitamin C serums are often recommended by dermatologists and estheticians to help protect the skin from sunlight and address hyperpigmentation.4 2. Epigallocatechin 3-gallate (EGCG)
3. Glutathione Glutathione is a powerful antioxidant that the body actually makes internally from three amino acids (AKA building blocks of protein): cysteine, glutamate, and glycine.6 Not only does this antioxidant protect the body against oxidative stress, it also supports healthy liver detoxification processes.7 Glutathione levels naturally decrease with age, and lower glutathione levels in the body are associated with poorer health.8 Since it takes all three of those amino acids to form glutathione, ensuring that the body has adequate levels of all three is vital. Cysteine is the difficult one. It’s considered the “rate-limiting” step in this equation, since it’s usually the one in short supply, and glutathione can’t be formed without it.6 Cysteine contains sulfur, so foods like unprocessed meat, garlic, and asparagus are great choices to support cysteine levels. Like cysteine, the compound N-acetylcysteine (found in supplements and often labeled NAC) can also be used to support the body’s glutathione levels.6
5. Vitamin E
Vitamin E is a fat-soluble vitamin, meaning it’s best absorbed with fat. It acts as an antioxidant by stopping the production of free radicals from forming when fat is oxidized, or burned.10 Vitamin E is found in nuts and seeds (almonds, sunflower seeds, and hazelnuts) as well as green leafy vegetables. Vitamin E also plays a role in heart, eye, and cognitive health.10 6. Quercetin Quercetin is one of the most well-studied flavonoids, or plant compounds, typically found in onions, kale, broccoli, apples, and tea. Quercetin acts as a free radical-scavenging antioxidant, helps inhibit oxidative stress, and supports a healthy immune response.11 What’s the bottom line? Antioxidants are a crucial part to any healthful diet. They help protect the body from damage caused by oxidative stress and support immune function. There are many more antioxidants that are beneficial to health than those listed here. The best way to ensure that you’re getting enough antioxidants from the diet and supporting the antioxidants the body makes on its own is to consume a diet high in plants like fruits, vegetables, nuts, seeds, and legumes. References
 by Cassie Story, RDN Abstract: Although it was not identified and isolated until the 1930s, vitamin C has been known to protect against and treat certain disease states since the 18th century. Ask any health care practitioner to recall the first nutrient deficiency they learned about, and vitamin C will likely top the list. Images of sailors in the 1700s returning to shore with bleeding gums, fatigue, and even death due to a deficiency in this potent, water-soluble, antioxidant micronutrient likely come to mind. Ask any consumers what nutrient they should take during cold and flu season to help minimize their risk of infection, and once again, vitamin C will typically be their reply. For these reasons, vitamin C is arguably one of the most famous micronutrients. This post will dive into the role of vitamin C within the body and the potential health benefits of optimal intake and review considerations for its impact on the immune and respiratory systems. Function of vitamin C in the body Unlike most animals, due to the result of random genetic mutations, humans have lost the ability to synthesize ascorbate in our livers, making vitamin C an essential micronutrient.1 This important antioxidant serves many functions in disease prevention and optimal health status. Vitamin C is involved in protein metabolism and is required for the biosynthesis of certain neurotransmitters, as well as L-carnitine and collagen. It also serves as a cofactor for several enzyme reactions.2 Mild insufficiency, or hypovitaminosis C, has been associated with low mood, and more severe deficiency can lead to the clinical syndrome of scurvy, a condition that remains diagnosed in individuals today—and has played a role in global public health outbreaks.3,4 As vitamin C is a regenerative antioxidant, research continues to evaluate the impact of vitamin C and its role in reducing the destructive effect of free radicals. This may assist in the prevention of or delay in certain cancers, cardiovascular disease, and other conditions where oxidative stress affects human health.5 Not only does vitamin C have biosynthetic and antioxidant functions, it plays an important role in immune function and assists in the absorption of nonheme iron. Vitamin C absorption and status Vitamin C concentrations are tightly controlled within the body. Despite this, studies indicate that hypovitaminosis C and deficiency exist worldwide. Hypovitaminosis C is prevalent within certain populations in developed countries, including individuals with obesity, those who smoke, and people with low fruit and vegetable intake—and is the fourth leading micronutrient deficiency in the United States.6 Dietary intake is a primary factor in an individual’s vitamin C status. The amount consumed and frequency of consumption correlate well with plasma status and deficiency risk.6 Well absorbed in small quantities (i.e.: 200-400 mg at a time), through sodium-dependent vitamin C transporter-1 (SVCT-1), the enterocyte is rapidly saturated, and vitamin C is then transported, at varying concentrations, to several body tissues.7 Many organs have concentration-dependent mechanisms to retain vitamin C during situations where supply is low, namely brain tissue and adrenal glands.8 Plasma saturation occurs at a concentration between 70-80 µmol/L, although typical laboratory assessment methods prove highly susceptible to inaccuracies—leaving it challenging for many clinicians to assess accurate vitamin C status in their patients.8 Factors that impact vitamin C status6  Recommended intake and sources Population-based studies indicate that a majority of Americans meet the recommended dietary allowance (RDA), which is 90 milligrams (mg) per day for males and 75 mg per day for females, although ideal intake and serum concentrations have been a topic of debate for health experts around the world, and recommended values are not universal.9 A range of identified health benefits have been observed at higher intake levels. This has led a number of international agencies to increase their dietary recommendations, as the previous recommendations were based on the low level needed to prevent scurvy, which is estimated to be 10 mg per day.9 Despite its popularity among health care professionals and consumers, average US adult intakes are estimated to be 105 mg for males and 84 mg for females.10 While it is apparent that most individuals meet the RDA, many do not achieve the estimated optimal intake needed for its positive biological impact—which is speculated to be much higher, with many experts suggesting a daily intake of 200 mg for optimal health.11 Food sources Fresh fruit and vegetables are the main contributors of dietary vitamin C, with fruit intake correlating strongly with plasma vitamin C levels.6 Major contributors of vitamin C in the typical American diet are potatoes, citrus fruit, and tomatoes. Foods rich in vitamin C include oranges, kiwi, berries, papayas, mangos, melons, spinach, asparagus, and Brussels sprouts.12  Impact of vitamin C supplementation Supplemental use Five or more servings of fruits and vegetables per day can often lead to an optimal daily vitamin C intake of 200 mg, with special attention to one or two servings coming from a high-vitamin C source. This is not always possible, and taking supplements—in addition to dietary intake, can help to achieve and maintain optimal status.
Dietary supplement sources The majority of dietary supplements provide vitamin C in the form of ascorbic acid, which has an equivalent bioavailability to the naturally occurring ascorbic acid found in food sources.16 Other forms of supplemental vitamin C include mineral ascorbates, liposomal-encapsulated, or combination products. The upper limit has been set at 2,000 mg per day, due to the potential of diarrhea or other gastrointestinal (GI) effects, not due to a potential toxic impact. Buffered forms have been shown to help prevent GI distress and offer higher absorption than traditional ascorbic acid, possibly related to the presence of other minerals and amino acids. One study on 22 healthy subjects found that a buffered form of vitamin C improved absorption in healthy individuals by 18-25% when compared to ascorbic acid.17 Immune, inflammation, and respiratory impact Vitamin C appears to play a role in both prevention and treatment of respiratory and systemic infections by boosting several immune cell functions.18 Vitamin C status may be depleted by various disease states due to inflammatory processes and greater oxidative stress. During times of active infection, requirements for vitamin C increase with the severity of the infection—which requires significantly higher intakes to reach normal plasma status to make up for the added metabolic demands.6 Prophylactic prevention, on the other hand, advises that dietary intake is, at minimum, adequate. However, in order to achieve plasma saturation and optimize cell and tissue levels, doses of 100-200 mg per day are suggested.18 The role of vitamin C in immune defense and inflammation is multifactorial. It plays a role in inflammatory mediators by modulating cytokine production, decreasing histamine levels, and offering protection of key immune enzymes. Apoptosis, the necessary programmed cellular death of neutrophils, supports the resolution of inflammation and helps to prevent extreme tissue damage. Caspases are oxidant-sensitive, thiol-dependent, key enzymes in the apoptotic process. Vitamin C is thought to protect the caspase-dependent apoptotic process following the activation of neutrophils. Numerous studies have found weakened neutrophil apoptosis in patients with severe infection when compared to control groups. Animal studies have shown that administration of vitamin C greatly reduced the numbers of neutrophils in the lungs of septic animals.18 Cytokines, cell-signaling molecules secreted by certain immune cells, respond to infection and inflammation and can elicit a pro- or anti-inflammatory response. Vitamin C has been found to regulate systemic and leukocyte-derived cytokines in a multifaceted way. Preclinical, in vitro and animal studies have shown both positive and unfavorable effects of incubation with vitamin C. The effect of vitamin C seems to depend on the cell type and/or the inflammatory stimulant but overall appears to assist in normalizing cytokine generation.18 Following chemical exposure, natural killer (NK) cell function, as well as T and B cell function, decreases and can remain low for several weeks to months.17 Studies have shown enhanced immune function and improvement in NK cell function after oral doses of buffered vitamin C, as well as T and B cell function improvement following toxic chemical exposure. One study, of 55 subjects, used individualized dosing (60 mg/kg of body weight) of buffered vitamin C to evaluate the impact of high-dose vitamin C following a toxic chemical exposure and found that functional immune abnormalities can be restored following such an event.19 Allergies and the common cold Histamine, an immune mediator, is produced in response to pathogens and stress. Vitamin C depletion is associated with higher circulating levels of histamine. Intervention studies with supplemental oral vitamin C (range 125 mg–2 g/day) have found a decrease in histamine levels; however, they have been more impactful in patients with allergic symptoms compared to infectious diseases.18 The impact of vitamin C intake on common cold incidence has been an area of interest for the last 50 years.20 Meta-analyses have indicated that supplementation with 200 mg or more per day is effective in reducing the severity and duration of the common cold, and in individuals who have inadequate vitamin C status, vitamin C supplementation may decrease the incidence of the common cold. Thus, it appears that taking high-dose supplemental vitamin C daily during cold and flu season may reduce the risk of cold duration and severity.21 Respiratory impact Exposure to air pollution oxidants and tobacco smoke can alter the oxidant-antioxidant balance in the body and lead to oxidative stress.22 When vitamin C levels are insufficient, antioxidant defenses are impaired and can further compound the impact of oxidative stress within the body. Environmental oxidants can damage the respiratory tract lining fluid and increase the risk of respiratory disease. Vitamin C acts as a free-radical scavenger that can scavenge superoxide radicals and oxidant air pollutants—and its antioxidant properties offer protection to lung cells exposed to oxidants caused by various pollutants, heavy metals, pesticides, and xenobiotics.23 Vitamin C also plays a role in proper endothelial function, and deficiency has been associated in pulmonary arterial hypertension.24 Patients with acute respiratory infections have been found to have low plasma levels of vitamin C, and supplementation has been found to return plasma levels to normal and decrease the severity of respiratory symptoms. Beneficial effects of vitamin C supplementation on recovery of respiratory infections, including pneumonia, have been identified. Studies on hospitalized patients with pneumonia have found that supplemental vitamin C at a low dose (250-800 mg/day) reduced length of stay by 19% compared to those without vitamin C supplementation. Those that were given higher doses (500 mg–1.6 g per day) had an even greater reduction at 36%.18 It appears that low vitamin C levels seen during respiratory infections are both a source and a result of the disease. Respiratory health case study10 In a recent case study, a man in his 60s experienced shortness of breath and swelling of the legs associated with a frank vitamin C deficiency, which was attributed to a diet low in vitamin C and no supplemental intake. He was treated with supplemental vitamin C at 1,000 mg twice daily; his symptoms resolved after five months on this treatment plan.
Genetic variants Recent discoveries in genetic variants’ influence on vitamin C status have been found. Several single-nucleotide variants have been identified in the SLC23A1 gene, which encodes SVCT-1 and is responsible for the active uptake of dietary vitamin C and the reuptake of filtered vitamin C in the kidneys. In vitro data for this variant indicates a 40-75% decrease in vitamin C absorption from the gut and has been shown to present in 6-16% in those of African descent.25 A common variant of the hemoglobin-binding protein haptoglobin (Hp2-2) influences the metabolism of vitamin C. In vitro studies have found that this alters the ability to bind to hemoglobin and leads to an increase in oxidation of vitamin C.26 The Hp2-2 variant seems to have a greater impact on individuals with dietary intakes of less than 90 mg of vitamin C per day.27 Individuals with genetic variants that influence vitamin C status may require even higher dietary intakes. Luckily, high-dose vitamin supplementation has been found to amend certain gene-variant defects.28 Conclusion A majority of individuals would benefit from increasing fruit and vegetable intake to improve overall nutrition status, including vitamin C. Ensuring adequate intake of vitamin C through diet and with the use of supplementation is important for proper immune function and resistance to infections. This is especially critical for individuals with certain genetic SNPs or other lifestyle factors that may lead to a decline in vitamin C status. Citations
Cassie I. Story is a Registered Dietitian Nutritionist with 17 years of experience in treating metabolic and bariatric surgery and medical weight loss patients. She spent the first decade of her career as the lead dietitian for a large volume clinic in Scottsdale, Arizona. For the past seven years, she has been working with industry partners in order to improve nutrition education within the field. She is a national speaker, published author, and enjoys spending time with her two daughters hiking and creating new recipes in the kitchen! |
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