Disclaimer: This post does NOT address COVID 19 pandemic prevention strategies, such topics are beyond the scope of this post. For information on COVID 19 preparedness and prevention, I suggest you go to CDC.gov.
You eat clean, natural foods. Maybe you eat mostly or exclusively whole grains, fruits, nuts, beans, lentils, and veggies. You avoid sweets, refined breads/ pastas, sugary soft-drinks, fast or fatty foods, manage your sleep and recovery, and exercise with strength training and/ or cardiovascular training consistently. You do your best to manage your work, life, and stress balance.
You meditate, or pray, walk, or do other activities to help counter your stress response. (If you’re not doing these things, they’re a great place to start!) And yet…you get sick. Maybe once or twice a year, or maybe more frequently. What is going on? First of all, your experience with common respiratory infections may be well within the average range. Adults suffer on average 2 to 5 respiratory infections per year (Lenoir-Wijnkoop, Gerlier, Bresson, Le Pen, & Berdeaux, 2015).
Still, you are trying your best to live a more healthy lifestyle than the average adult. Relatable? I have practiced a number of lifestyle interventions over the years and still find myself susceptible to respiratory illnesses. Advice, solicited and unsolicited, abounds…
Take this herb or that herb, or this supplement or that supplement. Cold baths, hot baths. Exercise more, exercise less. Eat this way, no eat that way. As usual, I am curious–what does the best current research say? What are evidence-based practice guidelines a person already living an active, healthy lifestyle might follow to further reduce susceptibility to illness and boost immunity?
Impaired immunity and respiratory infections: Heavy Exercises/Athletes at increased risk
An article in the journal European Journal of Sport Science provides guidance to athletes (or non-athletes who still like to train like athletes!) for maintaining immunity in spite of heavy training / exercise regimens or ambitious fitness goals (Walsh, 2018). According to the article, at least 35 years worth of research has identified a pattern demonstrating athletes experience increased rates of upper respiratory infections such as colds, flu, etc. during times of intense training or times of competition. While recently the negative impact of heavy exercise on the immune system has been questioned, most resources recognize heavy/ intense exercise as a stimulus that taxes the body’s immune system and recovery abilities (Maggini, Pierre, & Calder, 2018).
Isn’t exercise good for you? This post is the first in a series exploring why people who live healthy lifestyles still may be getting sick. The first of the series will focus on nutritional factors and the immune system.
Nutrition factors that impact your immune system function & what you can do
Deficiencies in a variety of nutrients including a deficiency in calories necessary to meet the energy demands expended can dampen the immune system’s effectiveness (Walsh, 2018). As such optimized nutrition is essential to give your body the best chance possible to resist infections. The following are recommendations I found in the research for athletes/ heavy exercisers to resist infection/ optimize immune function.
Macro-nutrient factors (protein & carbohydrates)
- Low carbohydrate diets raise your risk of infection due to increasing the release of immuno-suppressive hormones (Walsh, 2018).
- High carbohydrate diets (greater than 50% of caloric intake) are encouraged (Walsh, 2018). Whole, natural (minimally processed) plant-based diets are naturally high in quality carbohydrates and micro-nutrients!!!
- Protein intake should be at least 1.2 grams/kg to 1.6 grams/kg daily for athletes /those who are physically active. Note: this amount is less than what is frequently advertised in popular magazines and articles (Walsh, 2018).
- To find out your weight in kilograms (kg), take your weight in lbs and DIVIDE it by 2.2. Then multiply such by the grams of protein to find your protein requirement ranges.
- For more info on athletics, training, goals, and research-based protein requirements (and risks to consider), see my post “Protein! Sources, Amounts, & Health: Current Evidence.”
Micro-nutrient factors (vitamins, minerals, etc)
Micro-nutrients play a crucial role in terms of proper immune function (Marcos, Nova, & Montero, 2003). Interestingly, however, supplementation of micro-nutrients through use of multivitamins and minerals (with exceptions outlined in a section below) remains controversial and frequently proves no better than supplementing with a placebo in terms of immune health following strenuous exercise (Walsh, Gleeson, Pyne, Nieman, Dhabhar, Shephard, Oliver, Bermon, & Kajeniene, 2011). The following micro-nutrients in adequate amounts are essential to optimal immune function (Maggini et al., 2018; Marcos, Nova, & Montero, 2003):
- Vitamin A
- Riboflavin (B2)
- Vitamin B6
- Folate (B9)
- Those following plant-based diets have superior levels (Harland & Garton, 2016)
- Vitamin B12
- Vegans especially and vegetarians need to supplement with B12 (Skerrett, 2013)
- Vitamin C
- Omnivores/ meat eaters tend to have lower levels, those following plant-based diets have superior levels (Harland & Garton, 2016)
- Vitamin D
- Deficiency is common in persons following both plant-based diets and omnivores world wide (Magginie et al., 2018)
- Vitamin E
- Omnivores/ meat eaters tend to have lower levels, those following plant-based diets have superior levels (Harland & Garton, 2016)
- Vegans and vegetarians are at higher risk for deficiency (Pilis, Stec, Zych, & Pilis, 2014); Fortified cereals may be a good option for vegans
- Vegans are at higher risk for deficiency (Fuhrman & Ferreri, 2010)
Should i take a multivitamin/ mineral complex?
Should I take a multivitamin/ mineral complex? Experts repeatedly warn against mega-dosing vitamins (exceptions may be in cases where a medical provider has verified lab tested deficiencies of nutrients like vitamin B12 and D and where close monitoring via routine blood work plus dose adjusting occurs over time). Frequently, experts advise that multivitamins/ minerals have failed to consistently demonstrate various benefits such as reductions in heart disease, cancer, chronic illness, and dementia (National Institutes of Health, 2019).
However, the National Institutes of Health (NIH, 2019) acknowledge that a multivitamin and mineral may be beneficial for people that have a difficult time getting particular nutrients from their diet. In particular per the NIH, vegetarians and vegans may benefit from multivitamins and minerals to offset risks of deficiencies. As noted above, omnivores also have their own deficiencies, and research shows that (despite a common trend of animal product consumption), micro-nutrient deficiencies are common world-wide (Maggini et al., 2018). Further, researchers note that since absence or deficiency in a single micro-nutrient can undermine the immune system, and people commonly have more than one micro-nutrient deficiency, supplementation may not be a bad idea specifically for immune system purposes (Maggini et al., 2018).
Multivitamins/ minerals should be dosed as close to the daily intake requirements as possible. Excessive doses can lead to toxicity as found in various research studies (NIH, 2019). If using a multivitamin/ mineral, formulas from reputable companies tailored by sex and age are also suggested (NIH, 2019). More information on plant-based diets and avoidance of deficiencies can be found here.
My take after going through the research? Clearly, trying to get the nutrients naturally through whole foods is the best goal. During times of high infection transmission (or perhaps during heavy training), I’m feeling like a multivitamin / mineral meeting the above criterion is not necessarily a bad idea. I avoided such in the past, but i am feeling like during key times it may not be a bad idea. Being 99-100% plant-based most of the time, I already take vitamin B12 routinely and vitamin D (during winter/ if not getting sun). Harvard Medical School also takes a surprisingly positive stance on multivitamins/ minerals here.
Supplementation with the intent of improving immunity and avoiding infection in otherwise healthy adults remains very controversial and much of the research is of low quality, subject to bias, or hindered by small sample sizes (Walsh, 2018). However, there may be value in supplementing with:
- Blood levels can be checked by your health provider for the most accurate detection and treatment of vitamin D deficiency.
- The article in the journal European Journal of Sport Science recommends 1000 IU of D3 daily from Fall season to Spring season (Walsh, 2018)…however:
- I must reiterate that, for an individual, this is to an extent “guessing”…your health care provider can remove the guess work with a simple blood test and prescribe more or less vitamin D depending on your individual needs.
- Excess vitamin D is toxic, inadequate vitamin D poses numerous health risks–-this is definitely one that you want to have in the “just right” zone for your body. Your health care provider can help here (Marcinowska-Suchowierska, Kupisz-Urbańska, Łukaszkiewicz, Płudowski, & Jones, 2018).
Zinc acetate lozenges
The article in the journal European Journal of Sport Science suggests zinc acetate lozenges with totals of 75mg / day at the onset of symptoms of a cold (Walsh, 2018). Separate research shows optimal dosing ranges of 80-90 mg of zinc acetate per day (Hemilä & Chalker, 2015). Both research articles agree LESS THAN 75 mg/ day is insufficient per research. A study performed a meta-analysis on 3 randomized, double-blinded, placebo controlled trials combining results for 199 participants and found zinc acetate lozenges acted directly on the pharynx tissues and produced the following outcomes:
- Nasal discharge duration shortened by 34%
- Sneezing shortened by 22%
- Nasal congestion shortened by 37%
- Scratchy throat shortened by 33%
- Sore throat by 18%
- Hoarseness by 43%
- Cough by 46%
- Muscle aches by 54% (Hemilä & Chalker, 2015)
Zinc acetate lozenges are deemed superior to other zinc forms as the acetate readily releases the zinc molecules into the pharynx.
- Research suggests the zinc ions may interfere with viral replication (Hemilä & Chalker, 2015).
- High doses of zinc supplementation such as occurs when following this regimen are viewed as safe for healthy adults over the short term (such as a matter of two weeks).
- If continued at high doses over a period of months, zinc supplementation can interfere with other nutrients in the body and become potentially harmful (Hemilä & Chalker, 2015).
For those that travel or find themselves prone to sickness, a probiotic containing greater than 10 to the 10th power of live bacteria may be of benefit (Walsh, 2018). Several meta-analyses of probiotics have demonstrated efficacy of probiotics in protecting against either contraction or helping reduce the duration of a variety of respiratory illnesses (Lenoir-Wijnkoop et al., 2015).
- A Cochrane systematic review of 12 randomized controlled trials consisting of 3,720 participants of all ages noted probiotics to be superior to placebo in preventing upper respiratory infection frequencies (Hao, Dong, & Wu, 2015). The researchers cautioned however that the studies were small in size and there was potential for funding bias. Findings noted:
- Risk of having a respiratory infection when using probiotics dropped by 47% (Hao et al., 2015).
- Duration of a respiratory infection was reduced by approximately 2 days (Hau et al., 2015).
- Various Lactobacillus and Bifidobacterium species are the strains that have demonstrated efficacy in the cited research (Lenoir-Wijnkoop et al., 2015).
- Research suggests that either oral supplementation or consumption of fermented dairy products containing these live strains are effective means of supplementation (Lenoir-Wijnkoop et al., 2015).
I saved vitamin C for last. Supplementation with vitamin C remains controversial in terms of preventing or reducing upper respiratory infection frequency and severity. A systematic review by the esteemed Cochrane Database of Systematic Reviews noted that vitamin C supplementation does NOT reduce frequency of upper respiratory infections among the general population (Hemilä, & Chalker, 2013). There WERE interesting findings of the same review which included the following (as quoted directly):
“However, regular supplementation had a modest but consistent effect in reducing the duration of common cold symptoms, which is based on 31 study comparisons with 9745 common cold episodes ” (Hemilä, & Chalker, 2013, para 3). So according to the review, vitamin C supplementation did appear to reduce the duration of the common cold. Another quote from the review found the following:
“In five trials with 598 participants exposed to short periods of extreme physical stress (including marathon runners and skiers) vitamin C halved the common cold risk. The published trials have not reported adverse effects of vitamin C” (Hemilä, & Chalker, 2013, para 3). In a more recent research review, routine intake of vitamin C including prior to onset of symptoms and ongoing proved superior in reducing duration versus only administering vitamin C after onset of symptoms of respiratory illness (Hemilä, 2017).
It is noted that even a mild deficiency in vitamin C can lead to increased duration, frequency, and severity of respiratory symptoms when infected with a common respiratory virus (Hemilä, 2017). Some of the positive research findings concerning vitamin C therefore may be explained when the vitamin C was administered to persons with a generally lower dietary intake of vitamin C. As such, striving for a diet rich in vitamin C appears to have protective effects in terms of frequency, duration, and severity of respiratory illness (Hemilä, 2017). Persons following a plant-dominant diet tend to have higher vitamin C dietary intake (Harland & Garton, 2016).
Summary & my take moving forward
A healthy lifestyle that includes intense or prolonged bouts of exercise may expose our immune systems to unique challenges. These challenges may manifest as an increased susceptibility to respiratory infections. There is controversy about the relationship of intense exercise and immune function.
However, considering the average rate of upper respiratory infections per year for adults runs around 2-5 episodes annually, finding ways to reduce respiratory infection frequency seems reasonable regardless. High carbohydrate diets based predominantly on plants while assuring adequate protein intake and adequate micro-nutrient intake appear to be a research-backed strategy for reducing a person’s risk for common infections.
Strategic use of supplements to bolster the immune system during times of acute illness or even as a preventive appear to have some foundation in the research. For myself, eating a plant-based diet, adding now a multivitamin and mineral tab during intense training cycles or cold/ flu season, along with zinc acetate supplementation during times of acute cold onset will definitely be part of my strategy moving forward. I’m on the fence about supplementing with probiotics specifically for the Lactobacillus and Bifidobacterium species. Finally, I have never been tested for my personal vitamin D levels, but think I will be changing that this year!! Hope you learned some useful strategies!!!
Thanks for reading, hope you found this informative!!! Feel free to leave a comment, sign-up to receive email alerts of new articles, and share with a friend!
Healthy Lifestyle & Still Getting Sick? Part 2: Training Approaches
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