The world is still grappling with Covid-19 pandemic. Along with the rest of the globe, vaccination drive continues across India but with a possibility of the third wave of Covid-19 pandemic in the country. As such, strengthening our immune system naturally is the need of the hour to prevent severe disease outcome.
The body’s immune system is a complex mechanism that depends on delicate interplay between multiple factors, diet being one of the most crucial part of that mechanism. A single food or supplement can never boost immunity overnight. Consuming a nutritious balanced diet for long term can strengthen the immunity gradually.
However, there are unhealthy dietary habits that can certainly weaken your immunity. Here’s what we need to know about those habits and take suitable initiative to modify them.
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Eating too much sugar
Most of us already know the negative impact of sugar on our health, leading to weight gain and uncontrolled blood glucose. But many of us are yet to understand the connection between eating high amount of table sugar and effect on our immune system.
People living with type 2 diabetes are more susceptible to catch infections and take more time to recover.
In a large review, Nagham Jafar and colleagues have concluded that high blood glucose level inhibited function of neutrophil and phagocytes, two major components of innate immune system.
Not only refined white sugar but other forms of sugar also have direct impact on immune system. A study by Albert S and colleagues reported an oral consumption of 100 g carbohydrate from glucose, fructose, sucrose, honey, or orange juice all significantly decreased the capacity of neutrophils, a white blood cell to engulf bacteria up to 50% for 1 to 2 hours that lasted up to 5 hours.
Furthermore, high sugary diet has been found to be associated with hampering gut-microbiota function that made the body more vulnerable to infection.
An average Indian consumes approximately 10 spoons of sugar per day, which is equivalent to 18 kg of sugar per year. These numbers are alarming and resonate with the growing prevalence of type 2 diabetes, cardiovascular disease and other lifestyle disorders among Indians.
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Excess salt intake and immunity
Salty snacks like chips, instant noodles, crackers, processed, and junk foods affect the immune system by causing cellular inflammation and creating an autoimmune response to manage the inflammation.
An experimental study in 2017 found that reduction in salt intake per day from 12 g to 6 g was associated to decreased production of inflammatory markers such as interleukin (IL)-6 and IL-23, along with increased production of anti-inflammatory cytokine IL-10.
In a comprehensive review in 2015, authors commented that high salt levels interrupt normal function of macrophage cells, which function in adjusting tissue inflammation and help in wound healing.
Indians consume more salt per day than advised as reported by a 24-dietary recall-based survey in 2019 by Claire Johnson and colleagues involving 1,283 participants from north and south India. This study reported regular consumption of salt is 11 g/day in the country, higher than the World Health Organization’s standard recommendation of no more than 5 g salt intake/day. Authors also reported most of the salt intake was attributed by added salt in both part of the country.
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Consuming too much alcohol
National Institute on Alcohol Abuse and Alcoholism defines heavy drinking “for men consuming more than 4 drinks on any day or more than 14 drinks per week” and “for women, consuming more than 3 drinks on any day or more than 7 drinks per week.”
Excessive alcohol consumption makes you more vulnerable to respiratory diseases like Covid-19.
Alcohol affects both innate and adaptive immunity, drastically decreases host defenses, exposing chronic drinkers to an array of health problems, including pathogenic infections and systemic inflammation.
Ambrosia, a leading magazine for the alcohol beverage industry mentioned India is world’s 9th largest consumer of all alcohol by volume; one in every two bottles of whiskey bought around the world is now sold in India. Andhra Pradesh, Telangana, Tamil Nadu, Karnataka, and Kerala sell more than 45% of total liquor sold in India.
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Not eating enough fruits and vegetables
Fruits and vegetables are the rich source of vitamins, minerals, antioxidants, and other bioactive compounds that support overall health, prevent chronic illnesses, and reduce inflammation.
A 2018 review of 71 clinical trials, 12 observational studies found fruits and vegetables’ intake was associated with reduced inflammatory markers and enhanced immune cell profile.
Increased intake of fruits and vegetables improved antibody response of Pneumovax II vaccination in 83 older individuals aged between 65 to 85 years as reported in a randomized control trial by Andrew Gibson and colleagues.
India is the second-largest producer of fruits and vegetables in the world but an ICMR-National Institute of Nutrition report revealed that green leafy vegetables is the least consumed food groups in both rural and urban India.
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Eating higher omega 6 diet
Omega 3 fatty acid containing foods such as industrial seed oils are found to cause inflammation according to multiple research studies. Experts recommend a ratio of omega-6 to omega-3 fats as 1:1 to 4:1 to promote overall health.
Consuming ultra-processed, fried, fast, artificial sweetener, high fat, additive enriched foods also affect body’s immune system, according to Healthline.
A versatile, whole foods-based nutritious diet is crucial to maintain optimal function of immune system. Avoiding white foods like salt, sugar, refined flour, white polished rice can prevent inflammation, prevent cell damage.
Along with a balanced diet plate, regular physical activity, sound sleep, sound mental health are also important determinants. Remember, immunity boosting is a collective, ongoing process and can’t be achieved overnight.
Subhasree Ray is Doctoral Scholar (Ketogenic Diet), certified diabetes educator, and a clinical and public health nutritionist. She tweets @DrSubhasree. Views are personal.
(Edited by Prashant Dixit)