Air Quality: House Plants that Can Improve Indoor Air

Globally, some seven million deaths each year are linked to the effects of air pollution, according to the World Health Organization, making it the biggest environmental killer. Pollution kills more people than car accidents, diabetes or dementia.^[16]

Health Effects of Air Pollution on Kids

Fourth and fifth graders in El Paso, Texas, are more likely to have lower grade point averages if heavily exposed to contaminated air at home, according to a new study which is the first to look at kids’ exposure to air toxics—such as benzene, arsenic, lead, mercury, hydrochloric acid, toluene, vinyl bromide, xylenes, and diesel particulate matter—at home and its impact on their school performance.^[3]


Scientists suggest that children’s developing bodies are more susceptible to air pollution, which can harm their respiratory systems and brain. They also surmise that air pollution might hamper kids’ grades via at least two ways: 

1. Illnesses (mostly respiratory)
• That would make them miss school
2. Developmental problems
• Which result from long-term exposure of air toxics

How to Fight Indoor Air Pollution

Sometimes pollution came from unexpected places — in [16], it discovered that restaurant kitchens and indoor chemicals were a big source of contaminants.
To improve indoor air, you could grow some house plants as listed below:

Common Name	Scientific Name	Notes
Bamboo palm	Chamaedorea seifritzii	Also known as the reed palm, this small palm thrives in shady indoor spaces and often produces flowers and small berries. It tops the list of plants best for filtering out both benzene and trichloroethylene. They’re also a good choice for placing around furniture that could be off-gassing formaldehyde. Also consider: Areca palm Lady palm
Chinese evergreen	Aglaonema modestum	This easy-to-care-for plant can help filter out a variety of air pollutants and begins to remove more toxins as time and exposure continues. Even with low light, it will produce blooms and red berries.
English Ivy	Hedera helix	A study found that the plant reduces airborne fecal-matter particles. It has also been shown to filter out formaldehyde found in some household cleaning products.
Gerbera daisy	Gerbera jamesonii	This bright, flowering plant is effective at removing trichloroethylene, which you may bring home with your dry cleaning. It’s also good for filtering out the benzene that comes with inks. Add one to your laundry room or bedroom — presuming you can give it lots of light.
Anita Cane	Dracaena reflexa 'Anita'	Dracaena Anita is a top choice for beginners with houseplants because the variety is so easy to care for. While it tolerates a range of conditions, including low light, dracaena Anita grows best in bright light and high humidity. Grow dracaena Anita inside unless you live in USDA zones 10b or 11. In other zones, you can place your plant outside in the summer provided the temperatures do not get below 60 degrees Fahrenheit at night.  The soil's pH should be between 6.0 and 6.5. Water dracaena Anita infrequently. Because dracaenas are sensitive to fluoride, using distilled water is better than tap water. Fluoride can cause yellowing leaf tips or margins or dead, scorched areas on the plant's leaves. As with most houseplants, Dracaena Anita will filter harmful volatile organic compounds (VOCs) from indoor air.
Janet Craig	Dracaena deremensis "Janet Craiq"	The Dracaena Janet Craig Lisa, a relatively new variety, is a little pricey but virtually indestructible. NASA lists the Dracaena Janet Craig among its top ten Clean Air Plants.
Marginata	Dracaena marqinata	The red edges of this easy dracaena bring a pop of color, and the shrub can grow to reach your ceiling. This plant is best for removing xylene, trichloroethylene and formaldehyde, which can be introduced to indoor air through lacquers, varnishes and gasoline. Light: Relatively bright light. Water: Allow the plants to dry between waterings, but not completely. These are more susceptible to root rot, so be very careful never to allow them to sit in water. Temperature: They thrive between 65ºF and 80ºF. They will suffer if it gets too cold and cannot tolerate freezing. Soil: Loose, well-drained potting mix. Fertilizer: They have a lower need for fertilizer, so fertilizer lightly at the beginning of spring or twice a year with controlled-release fertilizer.
Mass cane/Corn cane	Dracaena massanqeana	It does well in low light conditions and its wide leaves are long and arc gracefully from the stalk. The temperature requirements for fragrans is a comfortable 75 degrees and the water requirements are low. Dracaenas are one of the plants used in the NASA Clean Air Study and has shown to help remove Formaldehyde.
Mother-in-Law's tongue (or Snake Plant)	Sansevieria laurentii	This plant is one of the best for filtering out formaldehyde, which is common in cleaning products, toilet paper, tissues and personal care products. Put one in your bathroom — it’ll thrive with low light and steamy humid conditions while helping filter out air pollutants. Snake plant is a heat-loving plant, and thrives best at 55 to 75 degrees F.  It will not tolerate cold or frost, and is only suitable for outdoor growing in USDA zone 10+. Water sparingly no more than once or twice per week, or your snake plant will rot.
Pot mum	Chrysanthemum morifolium	The colorful flowers of a mum can do a lot more than brighten a home office or living room; the blooms also help filter out benzene, which is commonly found in glue, paint, plastics and detergent. This plant loves bright light, and to encourage buds to open, you’ll need to find a spot near an open window with direct sunlight. In general, the plant is best fertilized once a month and watered two to three times a week depending on climate.
Peace lily	Spathyphvllum "Mauna Loa"	Shade and weekly watering are all the peace lily needs to survive and produce blooms. It topped NASA’s list for removing all three of most common VOCs — formaldehyde, benzene and trichloroethylene. It can also combat toluene and xylene.
Warneckei	Dracaena deremensis "Warneckei"	Combat pollutants associated with varnishes and oils with this dracaena. The Warneckii grows inside easily, even without direct sunlight. With striped leaves forming clusters atop a thin stem, this houseplant can be striking, especially if it reaches its potential height of 12 feet.
Ficus	Ficus benjamina	It does best in bright, sunny conditions but will also tolerate considerable shade. It requires a moderate amount of watering in summer, and only enough to keep it from drying out in the winter. A ficus in your living room can help filter out pollutants that typically accompany carpeting and furniture such as formaldehyde,  benzene and trichloroethylene. Caring for a ficus can be tricky, but once you get the watering and light conditions right, they will last a  long time.
Golden pothos	Scindapsus aures	Another powerful plant for tackling formaldehyde, this fast-growing vine will create a cascade of green from a hanging basket. Consider it for your garage since car exhaust is filled with formaldehyde. (Bonus: Golden pothos, also know as devil’s ivy, stays green even when kept in the dark.) Warning: If you have pets, you should avoid them because they can be deadly for pets.[13]
Azalea	Rhododendron simsii	Bring this beautiful flowering shrub into your home to combat formaldehyde from sources such as plywood or foam insulation. Because azaleas do best in cool areas around 60 to 65 degrees, they’re a good option for improving indoor air in your basement if you can find a bright spot.
Heart leaf philodendron	Philodendron oxycardium	This climbing vine plant isn’t a good option if you have kids or pets — it's toxic when eaten, but it's a workhorse for removing all kinds of VOCs. Philodendrons are particularly good at battling formaldehyde from sources like particleboard.
Spider Plant	Chlorophytum comosum	Spider plants have also been shown to reduce indoor air pollution in the form of formaldehyde, and approximately 70 plants would neutralize formaldehyde production in a representative (ca. 160 m2) energy-efficient house.

References

1. 15 houseplants for improving indoor air quality
2. A Study of Interior Landscape Plants for Indoor Air Pollution Abatement
3. Dirty Air Correlates with Lower Grades in Texas Schoolchildren
4. KArma Video
5. Living near nature linked to longer lives, says study
• Researchers found that women in greener areas had a 41% lower death rate for kidney disease, a 34% lower death rate for respiratory disease and a 13% lower death rate for cancer than those living in areas with less greenery.
• The results of the study aren't suggesting that people need to move far out to the country in order to live a long life, simply that any increased vegetation seems to be linked to lower mortality.
6. Your Favorite Housewares Are Spewing Poison Dust Inside Your Home
• Furniture, bath curtains, and computers generate at least 45 toxic chemicals that may be endangering you and your family.
7. Every country has terrible air pollution, but these are the world’s worst
8. Air pollution leads to more drug resistant bacteria, study finds
9. Can Smog Raise Breast Cancer Risk?
• Women who live where the air is thick with pollutants may be more likely to have dense breasts, a known risk factor for breast cancer, new research suggests.
10. All Forms of Air Pollution Raise Your Dementia Risk
11. Drug-Free Strategies to Lower Your Blood Pressure
• Air pollution has been shown to increase your risk of high blood pressure to the same degree as having a body mass index (BMI) of 25 to 30.
12. Research Concludes That Houseplants Are More Vital To A Healthy Environment Than Ever
• “Buildings, whether new or old, can have high levels of VOCs in them, sometimes so high that you can smell them [and] inhaling large amounts of VOCs can lead some people to develop sick building syndrome, which reduces productivity and can even cause dizziness, asthma or allergies […] we must do something about VOCs in indoor
  air.” 
13. 6 Common Indoor Plants That Are Highly Toxic
14. These are the world's most polluted cities
15. Time spent in “green” places linked with longer life in women
16. How safe is the air we breathe?

Health Benefits of Eating Fermented Foods

We're more microbe than we are person: Our bodies contain 10 times more bacteria than cells, meaning around 100 trillion microbes are crawling inside and on us. By far the largest collection—about 3 pounds' worth—hangs out in the stomach and intestines.

Video 1.  How Italian Gorgonzola Cheese Is Made | Regional Eats (YouTube link)

While historical evidence has linked harmful gut bacteria to everything from increasing diabetes risk to the formation of autoimmune diseases,^[24]  healthy gut bacteria are now being hailed as a possible solution in disease prevention.  One way to make your gut healthy is by consuming fermented foods—From Korean kimchi, Japanese tsukemono, Indian chutneys to the ubiquitous sauerkraut, yogurt and cheese, global cultures have crafted unique flavors and traditions around fermentation.

In this article, we will discuss the history of fermented foods and their potential health benefits.

History of Fermented Foods^[17]

The earliest record of fermentation dates back as far as 6000 B.C. in the Fertile Crescent—and nearly every civilization since has included at least one fermented food in its culinary heritage.  In some places they make up a 5% of daily intake, while in others their role can be as substantial as 40%. However, their global consumption is declining as traditional food systems give way to the influence of a western diet and fast foods.^[19]

Using locally available raw materials from plant or animal sources, people across the globe produce this type of food and drink either naturally or by adding starter cultures that contain micro-organisms. Micro-organisms transform these raw materials both biochemically (i.e., the nutrients) and organoleptically (i.e., the taste/texture/odor) into fermented foods. For example, sourdough belongs to the entire world. Until 160 years ago, everyone who was making bread was using sourdough.^[32]

Links between fermented foods and health can be traced as far back as ancient Rome and China, and remain an area of great interest for researchers in modern times. Asian civilizations in particular have a history of fermenting a wide variety of foods—Japanese natto (soybeans), Vietnamese mám (seafood), Chinese douchi (black beans), Lao pa daek (fish sauce), Korean banchan (side dishes)—that remain essential components of their everyday cuisine.

In some cases, fermentation is a critical component to food safety beyond preservation. In West African countries, garri is an important food source. It is made from the root vegetable cassava, which contains natural cyanides and, if not properly fermented, can be poisonous. Other foods, such as the Tanzanian fermented gruel togwa, have been found to protect against foodborne illnesses in regions that have poor sanitation.

Figure 1.  Putative mechanisms of fermented or Brassica vegetables against COVID-19. (A) Oxidative stress induced by SARS-CoV-2 after its binding to ACE2. (B) Preventive effects of cabbage and fermented vegetables through Nrf2 (Source: [40])

 

Health Benefits of Fermented Foods

"Let food be your medicine and your medicine be your food" – Hippocrates

"Fermented foods are potent chelators (detoxifiers) and contain much higher levels of probiotics than probiotic supplements, making them ideal for optimizing your gut flora." said Dr. Mercola.^[4,11] Because of their probiotic properties, including attachment to epithelial cells, immunomodulation, and competitive exclusion of pathogens, numerous probiotic microorganisms (e.g. Lactobacillus rhamnosus GG, L. reuteri, bifidobacteria and certain strains of L. casei or the L. acidophilus-group) are being intensively studied.^[25]

Potential health benefits of fermented foods include:

• Modulate intestinal microbiota 
• Peptides, bioactive compounds and strains occurring in kefir, can modulate gut microbiota composition, low-grade inflammation and intestinal permeability, which consequently may generate health benefits.^[37,38]
• Improve skin condition
• A study showed a significant improvement on all skin outcomes and suggest that atopical individuals may benefit from kefir intake, especially regarding their skin hydration.^[45]
• Help fight depression
• Consuming lactic acid bacteria may help fight depression and increase production of chemicals that control emotions, according to a researcher at National Yang Ming University.^[14]
• One type of sourdough bacteria, Lactobacillus reuteri, activates the gut-brain axis by stimulating the brain to release the social hormone oxytocin.^[35]
• Help immunity
• Cabbage contains precursors of sulforaphane, the most active natural activator of Nrf2. Fermented vegetables contain many lactobacilli, also potent Nrf2 activators. It is proposed that fermented cabbage may enhance Nrf2-associated antioxidant effects, which is helpful in mitigating COVID-19 severity.^[40]
• Among the numerous purported health benefits attributed to probiotic bacteria, the (transient) modulation of the intestinal microflora of the host and the capacity to interact with the immune system directly or mediated by the autochthonous microflora, are basic mechanisms.^[25,38]
• Enrich food with essential amino acids, vitamins, mineral and bioactive compounds
• During tempeh fermentation, vitamins like niacin and riboflavin are increased by using the starter culture Rhizopus oligosporus. 
• Thiamine and riboflavin increase during fermentation of idli, the fermented rice and black-gram (a type of legume) product of India and Sri Lanka.
• Pulque — one of the oldest alcoholic beverages prepared from the juices of cactus plants in Mexico — is rich in vitamins such as thiamine, riboflavin, niacin and biotin.^[1]
• Serum concentrations of MK-7 were significantly higher in frequent natto eaters, and natto intake resulted in a marked, sustained increase in serum MK-7 concentration.^[21,22]
• Help competitive exclusion of pathogens
• Help lower bone fracture risk
• A research in Japan has suggested the possibility that higher MK-7 level resulting from natto consumption may contribute to the relatively lower fracture risk in Japanese women.^[22]
• Meta-analysis of human studies indicated that probiotic consumption has significantly increased serum and urinary calcium levels and decreased PTH level.^[39]
• Note that increasing PTH level leads to more bone destruction by osteoclasts. 
• Help lower blood pressure 
• Research led by Jing Sun, PhD, of the Griffith Health Institute and School of Medicine at Griffith University in Australia, suggests that consuming probiotics from food sources and dietary supplements may improve blood pressure.^[16]
• Degrade anti-nutritive compounds
• Make foods edible
• In the fermentation process, micro-organisms can be coaxed into producing enzymes, which degrade anti-nutritive compounds and thereby make edible.
• Yogurt or Kefir (i.e., fermented milk) may help alleviate the symptoms of lactose malabsorption.^[1]
• The cultures used in making yoghurt and curds, contain substantial quantities of ß-D-galactosidase, something that is thought to help alleviate the symptoms of lactose malabsorption. 
• Yogurt, as a viscous food, may delay the stomach emptying and that way help lessen lactose intolerant symptoms.
• Bitter varieties of cassava tubers contain a potentially poisonous substance that can be detoxified via lactic acid bacteria, as in gari and fufu, fermented cassava root products from Africa.^[1]
• The fermentation process in soy beans removes the phytates, trypsin inhibitors and hemaglutinin.^[3]
• Make food with enhanced flavor and aroma
• Make foods more digestible
• The soy carbohydrates in tempeh become more digestible as a result of the fermentation process. In particular, the oligosaccharides associated with gas and indigestion are greatly reduced by the Rhizopus culture.
• Fermented soy products have more bioactive molecules than those that are non-fermented. This is because beta glucosidase from bacteria cleaves sugar off isoflavones in soy, converting them into the active compounds diadzein, genistein, and glycetein.

Photo Credit

• 李金明人物油畫

References

1. Benefits of Traditional Fermented Foods
2. Fermented bean curd (Wikipedia)
3. Health Benefits of Soy Beans (Travel and Health)
4. Learn How to Make Cultured Veggies at Home to Boost Your Immune System (Dr. Mercola)
5. Doenjang
• In traditional Korean cuisine, jukyeom (죽염, 竹鹽), which means "bamboo salt", is prepared by roasting salt at temperatures between 800 and 2000 °C^[12] in a bamboo container plugged with mud at both ends. This product absorbs minerals from the bamboo and the mud, and has been shown to increase the anticlastogenic and antimutagenic properties of the fermented soybean paste known in Korea as doenjang.
6. How to make Korean Kimchi (home style; in Chinese)
7. How to make Korean Kimchi (Korean style; in Chinese)
8. Fermented skate (Korean foods)
9. [Star Kitchen with U-KISS] "How to Make Kimchi"
10. Here's why wine snobs should probably be called bacteria snobs
• Region, environmental conditions and grape varieties shape the microbial communities of the grapes that make it into the fermentation process and shape wine quality
11. How Your Gut Flora Influences Your Health (Dr. Mercola)
12. The Little-Known Vitamin Essential to Your Health
13. Vitamin K2 as a potential therapeutic candidate for the prevention of muscle cramps in hemodialysis patients: A prospective multicenter, randomized, controlled crossover pilot trial
14. Chinese pickle zha cai (Mustard Greens)
• 台湾客家福菜益生菌「PS128」可抗憂鬱
• Lactic acid bacteria helps relieve depression: study
• Serotonin, which eases agitation, fatigue and chronic pain, increased 20 percent in mice with depression and doubled in mice without, the researcher said.
15. Complete genome sequence of Lactobacillus johnsonii FI9785, a competitive exclusion agent against pathogens in poultry.
• Because of their probiotic properties, including attachment to epithelial cells, immunomodulation, and competitive exclusion of pathogens, representatives of this group are being intensively studied.
16. Could consuming probiotics help lower blood pressure?
17. The History and Health Benefits of Fermented Food
18. Traditional non-alcoholic beverage, Togwa, in East Africa, produced from maize flour and germinated finger millet
19. Western Diets and Western Diseases (Travel and Health)
20. An introduction to the traditional fermented foods and beverages of Turkey
• Traditional fermented foods in Turkey include fermented milks (yoghurt, torba yoghurt, kurut, ayran, kefir, koumiss), cereal-based fermented food (tarhana), and non-alcoholic beverage (boza), fermented fruits, and vegetables (turşu, şalgam, hardaliye), and fermented meat (sucuk). 
21. Building Strong Bones (Travel and Health)
22. Japanese fermented soybean food as the major determinant of the large geographic difference in circulating levels of vitamin K2: possible implications for hip-fracture risk.
23. THE OCCURRENCE, GROWTH AND CONTROL OF PATHOGENS IN AFRICAN FERMENTED FOODS
24. Leaky Gut Syndrome and Autoimmune Disease (Travel to Health)
25. Probiotics, prebiotics, and synbiotics
26. How Does the Gut Flora Influence Our Health? (Travel to Wellness)
27. 發酵食品：可以產生有益菌及維他命B12 (in Chinese)
28. Immune homeostasis, dysbiosis and therapeutic modulation of the gut microbiota
29. Cornucopia Yogurt Buyer's Guide
30. Parkinson's Disease Linked to Microbiome
31. Geypens B, Claus D, Evenepoel P, Hiele M, Maes B, Peeters M, Rutgeerts P, Ghoos Y. Influence of dietary protein supplements on the formation of bacterial metabolites in the colon. Gut. 1997 Jul;41(1):70-6.
• In general, fermentation of carbohydrates is considered to be beneficial, whereas fermentation of proteinaceous material (putrefaction) is considered to be detrimental.
32. Inside the World’s Only Sourdough Library
33. 9 Delicious Probiotic-Rich Foods (That Aren’t Yogurt)
34. Fermented or Unfermented Soy Foods for Prostate Cancer Prevention?
• The answer is unfermented soy foods.  So, for prostate cancer prevention, you want to go for unfermented soy foods.
35. Eat to Beat Disease: The New Science of How Your Body Can Heal Itself
• One type of sourdough bacteria, Lactobacillus reuteri, has remarkable health functions. It has been shown to improve immunity and suppress tumor development. L. reuteri also reduces weight gain and can speed wound healing.
36. Effect of Lactobacillus casei on lipid metabolism and intestinal microflora in patients with alcoholic liver injury
• Supplementation of Lactobacillus casei can improve lipid metabolism and regulate intestinal flora disorders in patients with alcoholic liver injury.
37. Kefir and Intestinal Microbiota Modulation: Implications in Human Health
38. Gut-microbiota-targeted diets modulate human immune status
• Fermented-food diet increases microbiome diversity and decreases markers of inflammation
39. Probiotics as a New Regulator for Bone Health: A Systematic Review and Meta-Analysis
40. Cabbage and fermented vegetables: From death rate heterogeneity in countries to candidates for mitigation strategies of severe COVID-19
41. Bouhnik Y et al. Effects of Bifidobacterium sp fermented milk ingested with or without inulin on colonic bifidobacteria and enzymatic activities in healthy humans. European Journal of Clinical Nutrition 1996 Apr; 50(4):269-73.
42. Gyawali R et al. The role of prebiotics in disease prevention and health promotion. Chapter 12 in Dietary Interventions in Gastrointestinal Diseases, 2019. Pages 151-67.
43. Mahboobi S et al. Effects of prebiotic and synbiotic supplementation on glycaemia and lipid profile in type 2 diabetes: A meta-analysis of randomized controlled trials. Advanced Pharmaceutical Bulletin 2018 Nov; 8(4):565-74.
44. Nowak A et al. Antigenotoxic activity of lactic acid bacteria, prebiotics, and products of their fermentation against selected mutagens. Regulatory Toxicology and Pharmacology 2015 Dec; 73(3):938-46.
45. Homemade Kefir Consumption Improves Skin Condition—A Study Conducted in Healthy and Atopic Volunteers (accessed on 11/14/2021)
46. Partial to Pickles? (Dr. Andrew Weil)
• I’m a big fan of pickled foods, but I prefer the ones that have been naturally fermented and contain live organisms.