March 25, 2019

 THE NUTRITIONAL STUDIESTHE DO 

Antioxidants and Asthma Antioxidants are a class of chemicals found primarily in high volumes in stressed plants as a defense mechanism against their predation. When we consume these foods, we presume that we garner the benefits of their function in our body. For our purposes, the definition of an antioxidant is a chemical that inhibits the damage to our cells from natural oxidation events that occur in the body during inflammation or infectious killing events*.

Essentially, they cool down inflammation post infectious or disease activity at the cellular level. The scholarly research data to date on this effect as it relates to asthma amelioration are very mixed and not inspiring. (Allen et. al. 2009)(Casino et. al. 2009)(Han et. al. 2014) Vitamins A, C and E are the principle antioxidants and chemicals involved in immune function and many other pathways. According to one large meta-analysis, their insufficiency is associated with worse asthma lung function and wheezing in asthmatic populations.(Allen et. al. 2009) The mechanism of action is plausible for vitamin A acting as a cofactor for correct innate immune function and immune dampening via T regulator cell function.(Raverdeau et. al. 2014) Vitamin C has a mechanism of action as a reducing agent to clear oxygen radicals and reduce oxidative damage to tissues. It has also been associated with reduced exercise induced bronchospasm. (Hemilia et. al. 2012) Vitamin E has the ability to bind up overloaded oxidative chemicals that are triggered by air pollution which in turn is known to worsen asthma. (Han et. al. 2014)

The balance point for antioxidants is important as they are critical for cellular induced pathogen killing when an infection is taking root in our lung tissue or other location. Taking too many supplemental antioxidants can paradoxically worsen asthma as infections are a major exacerbant of reactive airway issues. Mechanistically, this would occur when pathogen killing is weakened by too many vitamins blunting the oxygen radical killing mechanisms of of immune system.

Food sources of vitamin A are dairy, fish, liver, red/orange/green vegetables like carrots, sweet potatoes and green leafy spinach. Vitamin C is found primarily in citrus foods like oranges and grapefruits. Other good sources include brassica vegetables broccoli, cauliflower and brussel sprouts as well as leafy greens and peppers. Vitamin E food sources are nuts, nut butters, seeds, certain fish, avocados and fortified foods like cereals.

There are no good quality studies to warrant the use of high dose supplemental antioxidant vitamins in order to ameliorate asthma.

However, I think that it is prudent to consume antioxidant foods based on the mechanistic pathways of immune function even in the absence of quality data to support their consumption. In my mind, the only potential downside to antioxidant consumption would be to megadose vitamins where infection killing is needed via the reactive oxygen species pathways discussed above. In all of my reading, I cannot find a downside to the consumption of whole foods with antioxidants as part of high quality diet.

 

The story continues next week,
Dr. M

Allen Thorax Article
Cassano Thorax Article
Raverdeau Journal of Immunology Article
Hemilia British Medical Journal Open Article
Han Lancet Respiratory Medicine Article
Linus Pauling Micronutrient Center

*The antioxidant plays a role in cleaning up reactive oxygen species that are DNA damaging in high volume. Many things promote excessive amounts of reactive oxygen species (ROS) formation including exogenously ingested chemicals like smoke, toxins, drugs, as well as inflammatory food. We naturally make ROS during day to day cellular metabolism, intense exercise or to kill microbes.

ROS are chemically reactive molecules that have an unpaired electron. In the normal state, most electrons are paired off to keep them stable in the oxygen molecule. When they are unpaired they are unstable, dangerous and looking for an electron to steal. Imagine an amoral single guy being invited to a couple's party. He meanders around the crowd and doesn't care with whom he hooks up with as long as he does. In the cellular world the unpaired electron will attack any cell stealing its electron causing stress and damage. Cells suffer DNA and protein dysfunction, which in turn causes the cell to not perform properly or flat out die.

Antioxidants in this situation are your best friend watching your amoral guest meander around the party eyeing your wife or your friend's wife. Once he sees his true intent is damage, he grabs him by the arm and goes Bruce Lee on him taking him out of circulation.

Vitamin C is necessary to regenerate the cleaning capacity of vitamin E via a chemical called glutathione. Maintaining adequate volumes of vitamin C is critical.