COVID-19 has proven to be challenging and have introduced a “new normal” to life as we know it. Although it would appear that the virus outbreak In Canada is somewhat in control at this point, health authorities suggest that second and even third waves may be coming in the fall and winter. One encouraging outcome of this crisis is that many consumers are seeking ways to improve their overall health. The stress around COVID-19 has also led to an increasing interest in the role that diet can play in a strong immune system.
The “COVID-19: Economy Report” published in early April by IRi found that total mass multi-outlet and convenience store dollar sales of immunity products jumped over 200% in Canada and the U.S. (1). The number of immunity product buyers in the U.S. increased by 125%.
In order to build immune, “wellness” consumers are focusing on managing stress, ensuring adequate rest/sleep, and eating a healthy diet (2). The Hartman Group’s March 2020 podcast, “The Coronavirus Crisis: How the Core Wellness Consumer Thinks About Immunity Through Proactive Resilience”, reported that these consumers have increased their intakes of omega-3 foods and oils while reducing omega-6 oils and sugar/carbohydrates.
The role nutrition plays in supporting the immune system is well-established. A wealth of mechanistic and clinical data show that vitamins, including vitamins A, B6, B12, C, D, E, and folate; trace elements, including zinc, iron, selenium, magnesium, and copper; and omega-3 fatty acids play important and complementary roles in supporting the immune system. Inadequate intake and status of these nutrients are widespread, leading to a decrease in resistance to infections and as a consequence an increase in disease burden (3).
The immune system protects the body from invading pathogens, such as viruses or bacteria. It comprises a unique group of immune cells as well as cell-independent mechanisms. Immune cells include a wide array of compounds such as macrophages, neutrophils, eosinophils, basophils, mast cells, natural killer cells, and dendritic cells which are the first cellular line of defense. B cells and T cells have a higher level of specificity which delay activation (4).
The positive effects of omega-3 fatty acids on the immune system have been described for over 30 years. In a recent review highlighted in flaxresearch.com (4), Gutiérrez et al (2019) confirmed the importance of the role of omega-3 fatty acids in the functioning of the immune system. The review considers the effects of omega-3 fatty acids on the immune cells listed in the previous paragraph.
Omega-3 alpha-linolenic acid (ALA) impacts the immune system by changing the fatty acid composition of membrane phospholipids, and therefore regulate cellular membrane properties such as membrane fluidity or complex assembly in lipid rafts. Gutiérrez et al (2019) note a new role for omega-3 fatty acids and their derivatives as signaling molecules acting to disrupt pro-inflammatory cascades, alter cell signaling, cytokines and pro-inflammatory mediators.
Flaxseed has a unique mix of fatty acids being low in saturates (less than 9% of total fatty acids) and containing the essential polyunsaturated fatty acids, omega-3 ALA and omega-6 linoleic acid (LA). Approximately 57% of the fatty acids are ALA, making flaxseed the richest plant source of this important omega-3.
ALA may decrease inflammation and strengthen the immune systems via its influence on eicosanoids – hormone-like substances that play a role in controlling inflammation. When omega-3 ALA intake is low and omega-6 LA intake is high, pro-inflammatory eicosanoid production from LA is favoured. The opposite occurs when diets are both higher in ALA and lower in LA. A pro-inflammatory environment is associated with chronic disease risk and is a serious symptom of a COVID-19 illness. Increased ALA intake may thus offer protection against viruses such as COVID-19. Key research is briefly reviewed here.
In a randomized crossover design, 10 healthy males age 21-37 years consumed either basal diet or basal diet + 31.7 g/day flaxseed oil for 56 days. The flaxseed oil supplement suppressed the proliferation of peripheral blood mononuclear cells cultured with T-cell mitogen. The authors concluded that the flaxseed oil tended to suppress unfavorable indices of cell-mediated immune function (5).
In another study, eight systemic lupus erythematosus (SLE) patients (2 males and 6 females aged 32 to 72 years, mean = 44.5 years) consumed 15 g/day milled flaxseed for 4 weeks, then 15 g twice a day (30 g/day) for the ensuing 4 weeks, and finally 15 g three times a day (45 g/day) for the next 4 weeks, followed by a 5-week washout period. Measures of serum immunology were assessed. Pro-inflammatory CD11b expression on neutrophils was significantly reduced with the 30 g dose (6).
Faintuch et al. (2007) administered 30 g/day of flaxseed or manioc flour (placebo) to 24 morbidly obese outpatients, 4 males and 20 females with a mean age of 40.8 years, in a randomized double-blind placebo-controlled crossover study. Each treatment period was 2 weeks with a 24-hour wash-out period. Flaxseed significantly reduced the inflammatory markers C-reactive protein, serum amyloid A, and fibronectin, but not complement fraction C3, or complement fraction C4. The investigators attributed the immune-modulatory effect to the ALA content of the flaxseed (7).
Several new studies described on flaxresearch.com confirm and expand these early results. Bashir et al. (2019) evaluated the effect of flaxseed oil (FXO) supplementation on adipose tissue macrophages (ATM’s), E and D series resolvin (Rv) levels and adipose tissue inflammation. Male C57BL/6J mice were divided into five groups (n = 5): lean group (given standard chow diet), HFD group given high fat diet until they developed insulin resistance and 4, 8 or 16 mg/kg group (HFD group later orally supplemented with 4, 8 or 16 mg/kg body weight flaxseed oil) for 4 weeks (8).
In this study, FXO supplementation led to enhanced omega 3 fatty acids, DHA and EPA. Higher levels of immune stimulating resolvins, RvE1-E2, RvD2, RvD5- D6 were noted. Increased levels of IL-4, IL-10 and arginase 1 levels in ATMs together with altered immune cell infiltration and reduced NF-κB expression were found. The FXO supplementation suppressed immune cell infiltration into adipose tissue and altered adipose tissue macrophage phenotype towards the anti-inflammatory state via increases of E and D series resolvins, arginase 1 expression and anti-inflammatory cytokines level (IL-4 and IL-10) leading to an enhancement of the immune system in these mice (8).
The potential immune system effects of ALA on acute lung injury (ALI) showed protective effects in an animal model of ALI. Treatment with ALA significantly alleviated the infiltration of total cells and neutrophils into lung cells and increased the number of macrophages. ALA significantly inhibited the secretion of proinflammatory cytokines including tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1β (IL-1β) and increased anti-inflammatory cytokine. ALA also significantly inhibited the phosphorylation of IκBα and NF-κB (p65) activation in ALI. The authors speculated that NF-κB pathway may be involved in ALA mediated protective benefits (9).
The effects of ALA on the immune biomarkers, phospholipase A2 (PLA2), immunoglobulin E (IgE), interleukin 4 (IL-4), interferon gamma (INF-γ) level and INF-γ/IL4 ratio in bronchoalveolar lavage fluid (BALF) of sensitized rats has been examined. The effects of all concentrations of ALA on INF-γ, IL-4, INF-γ/IL4 ratio and IgE levels were significantly higher than control. The results showed an immune modulatory effect of ALA that increased INF-γ, INF-γ/IL4 ratio and decreased IL-4 in sensitized rats. ALA also showed preventive effect on inflammatory markers (10).
These findings support a positive immunomodulatory effect of ALA on different cells of the immune system. As consumers adapt to the COVID-19 crisis, buying habits have shifted and major trends have been upended, but a focus on a healthy immune system has been rising. Dietary flaxseed, already known for its strong antioxidant and anti-inflammatory properties, works as both a mitigator and protector of the various cells associated with immune responses to viruses. Numerous other studies describing the effects of ALA on the immune system can be reviewed at flaxresearch.com.
References
- “COVID-19: Economy Report”. IRi. April 2020. https://www.iriworldwide.com/iri/media/library/covid-19-thought-leadership-4-3-2020.pdf
- “The Coronavirus Crisis: How the Core Wellness Consumer Thinks About Immunity Through Proactive Resilience”. Hartman Group. March 2020. https://www.hartman-group.com/podcasts/1270084195/the-coronavirus-crisis-how-the-core-wellness-consumer-thinks-about-immunity-through-proactive-resilience
- Calder PC, Carr AC, Gombart AF, Eggersdorfer, M. 2020. Optimal Nutritional Status for a Well-Functioning Immune System Is an Important Factor to Protect against Viral Infections. Nutrients, 12, 1181.
- Gutiérrez S, Svah, SL, Johansson, ME. 2019. Effects of Omega-3 Fatty Acids on Immune Cells. J. Mol. Sci.20, 5028.
- Kelley DS, LB Branch, JE Love, PC Taylor, YM Rivera, JM Iacono. 1991. Dietary alpha-linolenic acid and immunocompetence in humans. Am J Clin Nutr 53:40-46.
- Clark WF, A Parbtani, MW Huff, E Spanner, H de Salis, I Chin-Yee, DJ Philbrick, BJ Holub. 1995. Flaxseed: a potential treatment for lupus nephritis. Kidney Inter 48:475-480.
- Faintuch J, LM Horie, HV Barbeiro, DF Barbeiro, FG Soriano, RK Ishida, I Cecconello. 2007. Systemic inflammation in morbidly obese subjects: response to oral supplementation with alpha-linolenic acid. Obesity Surg 17:341-347.
- Bashir S, Sharma Y, Jairajpuri D, et al. PLoS One. Alteration of adipose tissue immune cell milieu towards the suppression of inflammation in high fat diet fed mice by flaxseed oil supplementation. PLoS One. Oct 17;14(10):e0223070. doi: 10.1371/journal.pone.0223070.
- Zhu X, Wang B, Zhang X, et al. 2020. Alpha-linolenic acid protects against lipopolysaccharide-induced acute lung injury through anti-inflammatory and anti-oxidative pathways. Microb Pathog. Feb 18:104077. doi: 10.1016/j.micpath.2020.104077.
- Kavesh M, Eftekhar N, Boskabady MH. 2019. The effect of alpha linolenic acid on tracheal responsiveness, lung inflammation, and immune markers in sensitized rats. Iran J Basic Med Sci. Mar;22(3):255-261. doi: 10.22038/ijbms.2019.27381.6684.