Pretend you eat a perfect diet every single day. I say “pretend” because I don’t think it’s truly possible for anyone to eat perfectly all the time, but for argument’s sake, let’s say you eat exactly as top nutritional experts recommend: You get all the nutrients you’re supposed to and avoid every ingredient on the “no” list, plus you take in just the right amount of calories for your personal needs.
Well, I’m here to tell you that even then — even if you’re doing everything right — there’s still something crucial missing from your diet that used to be there. That something is phytochemicals.
Phytochemicals are specialized, bioactive compounds found in plants and herbs that come with a huge list of known health benefits — and we’re only just beginning to scratch the surface of what they can do for us. But unfortunately, phytochemicals have become increasingly less prevalent in the plant foods we eat today, especially compared to those consumed by the generations before us.
In fact, the plant foods you find at your grocery store or local farmer’s market are almost unrecognizable from what was available even just 100 or so years ago in how they look, taste, and especially their phytochemical and nutrient composition, according to a paper in the journal HortScience. In the study, author Donald R. Davis completed and reviewed research comparing modern fruits and vegetables with those from 50 to 70 years prior.
What Davis found: A “dilution effect” or decline of nutrients over the decades, with median declines of 5% to 40% or even more of some nutrients. Davis noted that, although more research is necessary, it’s likely there’s been a decline or dilution in the hundreds of phytochemicals found in plant foods as well. It makes sense when you consider that modern farming and cultivation of crops over the years has favored foods with increased carbohydrate and sugar content and that grew quickly and to large sizes — all at the expense of its phytochemicals.
Of course, it wasn’t necessarily the intention to breed out these beneficial compounds, but little attention was given to nutrition. Instead, as farmers made it easier for crops to grow by using pesticides and herbicides, for instance, the plants no longer had a reason to develop the same phytochemicals — which play a key role in protecting plants from outside threats — that their wild predecessors did. Modern agriculture also contributed to the depletion of nutrients in the soil over time.
Likewise, people naturally preferred the sweeter and milder flavors that came with higher sugar content and fewer phytochemicals, which tend to have a very bitter flavor. And up until the past 50+ years or so, people wanted the extra calories that came with those higher carbohydrate levels because food scarcity was a concern for everyone. And so, the mechanisms developed to process grains that we still use today strip away beneficial phytochemicals while concentrating sugar content.
Just how much fewer phytochemicals are we getting in our food today compared to in the past? In some cases we’re getting a tiny fraction of the original amount, according to Jo Robinson, an investigative journalist and author of the book Eating on the Wild Side. In an article in The New York Times, Robinson shared some of her research showing the stark nutritional differences in heirloom and wild varieties of similar types of foods. (Heirloom varieties are grown from old seeds — sometimes a hundred or more years old — and so the plants they grow haven’t been “messed with” or artificially changed or altered in any way.)
Robinson reported that heirloom purple Peruvian potatoes, for example, contain 28 times more of a type of phytochemical called anthocyanins as today’s russet potatoes. Likewise, the apples, corn, berries, and greens our ancestors consumed contained sometimes hundreds of times the phytochemicals and nutrients of today’s versions.
That’s not to say today’s plant foods are worthless. Quite the opposite: Fruits and vegetables still contain some phytochemicals, not to mention vital nutrients like fiber, vitamins, and minerals. What’s more, studies show that people who eat more plants are healthier by multiple different metrics and live longer than those who eat less.
But the truth remains that fruits and veggies simply can’t deliver all the phytochemicals your body could benefit from. And understanding how to get enough phytochemicals from sources beyond fresh produce can make all the difference in your well-being today and for decades to come.
Before we discuss the best ways to increase your intake of phytochemicals, it helps to first understand exactly what they are. The terms phytochemical and phytonutrient are often used interchangeably to mean compounds found in plants (phyto means plant in Greek) that serve a useful purpose for the plant and, by extension, the humans or animals who consume it. However, when you think about what these compounds do — and what plants and humans are utilizing the compounds for — it makes sense to separately define them.
Technically, a nutrient is something a living organism needs to survive. Nutrients are the raw materials organisms use to generate energy or perform other essential functions for life, such as produce hormones or repair cells. Phytonutrients would refer to any nutrients that are sourced from plants. The list includes carbohydrates (including fiber), fats, amino acids from proteins, vitamins, and minerals — plants are an adequate source for all of the above.
Any one plant source, however, doesn’t typically contain the full spectrum of all possible phytonutrients. For instance, broccoli and zucchini are a great source of vitamins, minerals, and fiber, but not amino acids and fats — beans are a better source of those phytonutrients. Technically, the starches and sugar found in cane sugar and white bread are phytonutrients, even though consuming processed carbohydrate phytonutrients is decidedly unhealthy.
Phytochemicals, on the other hand, refers to something completely different. Phytochemicals are chemical compounds that plants use to neutralize threats or provide protection against stress factors. All plants produce a wide array of different phytochemicals to counteract their own top threats.
Phytochemicals also give fruit, vegetables, and other plants and herbs their color, taste, and/or smell. They’re what make cruciferous vegetables like broccoli bitter, and what give certain fruits their intense color.
For the plants themselves, phytochemicals serve two primary functions:
1. Phytochemicals provide protection from environmental stressors and threats.
Because plants rely almost exclusively on phytochemicals for defense, they work really, really well. They have to in order for the plant to withstand outside threats such as insects, pathogenic microbes, and environmental stressors like harsh climates. Without successful protection, a plant species becomes extinct. So, while we humans fight infections from viruses, bacteria and other threats primarily through a cellular immune system, which uses the nutrients we eat (fats, carbohydrates, minerals, vitamins) to function properly, plants have evolved to make phytochemicals for that job.
Plants also have a microbiome — a collection of microbes it plays host to — just like we humans do, and it’s similarly important for growth, health, and survival. However, like our own microbes, a plant’s microbial balance can be thrown out of whack by an overgrowth of pathogenic organisms or an imbalance of some kind. Its natural phytochemicals help suppress those damaging microbes and maintain microbiome diversity and homeostasis (balance).
2. Phytochemicals promote cellular communications for survival.
The constant dialogue that happens between cells is vital for proper functioning and staying healthy and alive, and plants make the specific phytochemicals they need to keep communication flowing. Humans’ cellular communication, meanwhile, is enabled by nutrients, which help us make hormones and neurotransmitters that serve as messengers. Our body’s vast microbiome likewise plays an important role in cellular communication.
What has been clear to practitioners of ancient herbal medicine for centuries is that the phytochemicals plants make to protect themselves and facilitate cellular communication can also help humans in similar and additional ways. In fact, while they’re not absolutely essential for your survival, regularly consuming phytochemicals may be one of the most important things you can do to protect your health.
When you consume phytochemicals, you gain all the plant’s natural defenses. Because different plants produce different spectrums of phytochemicals, depending on the prevalence and types of stress factors where the plant evolved, consuming a variety of different plants provides a wide range of different benefits — the greater the variety, the better.
Fortunately, modern scientists are also now recognizing this connection, and learning more and more about what’s happening on a cellular level to help our bodies function more optimally and efficiently, especially under conditions that might otherwise cause us problems.
Phytochemicals are Multi-Talented Team Players
Thousands of individual phytochemicals exist in nature, and only relatively recently have experts begun to identify and learn more about some of the various individual compounds and their families of chemicals. A few that have been widely studied and that are common in food include:
- Resveratrol and pterostilbene: Part of the polyphenol family, resveratrol and pterostilbene are prevalent in grape skin and berries, and they’re known to have cardio-protective benefits.
- Lutein and zeaxanthin: Both carotenoid phytochemicals, lutein and zeaxanthin are bright-colored pigments that show up in yellow, orange, and red produce like squash and red peppers as well as in dark, leafy greens like kale and spinach. (The chlorophyll content in greens mask the yellow/orange pigment.) Of the more than 600 different carotenoids, these two have been shown to be especially beneficial for eye health.
- Anthocyanins: A type of flavonoid that gives red, purple, and blue berries and other plants their rich pigment, anthocyanins help with blood pressure, among many other benefits.
- Sulforaphane and glucosinolates: They belong to the isothiocyanate class of phytochemicals. Common in cruciferous veggies such as broccoli, cabbage, and Brussels sprouts, they may help fight cancer.
These and the handful of other well-known phytochemicals are truly a drop in the bucket when you consider the sheer number of different plants, herbs, spices, and fungi that exist in nature, each of which contain hundreds or even thousands of unique phytochemical compounds. What’s more, while it’s beneficial for scientists to study individual phytochemicals and the one or two main ways they keep us healthy, it can be a mistake to think in such narrow terms.
For one, a plant’s phytochemicals almost always work synergistically, or as part of a “team,” with the other chemicals and nutrients that naturally occur within the plant. In that way, phytochemicals are a bit like a baseball team: You have players who are individually skilled and talented, but in order for them to truly shine and the team to achieve its goal of winning, they must work together, and they need chemistry, great coaching, solid plays, the right gear, etc. Take any of those elements away, and no individual player performs as well.
Similarly, just as the best players aren’t only great at hitting or throwing or running, rather they tend to do many things really well and be great all-around athletes, so too do phytochemicals work in multiple different, beneficial ways. Because of that, phytochemicals offer several levels and avenues of protection and support, which provides a wide range of benefits that ultimately trigger a health-promoting ripple effect. So while you can live without phytochemicals, you’ll live better, healthier, and longer with them.
Phytochemicals in Action
Phytochemicals often share many of the same (and multiple) general benefits in humans, but how they work or their specific mechanisms of action may differ. For example:
In order to turn the nutrients you eat into usable energy, break down and dispose of damaged tissue and cellular debris, fight infections and perform other functions, your body makes what are called free radicals or reactive oxygen species. These unstable molecules steal electrons from other molecules (like carbs or fat or tissue or pathogenic microbes), which destabilizes them so your body can then properly deal with them.
This electron thievery is a good thing in that it can facilitate certain necessary functions, whether it’s making the carb or fat molecule easier to convert into energy or cleaning up damaged tissue, for example. Your mitochondria — the power plants that live within each cell and make energy — also produce free radicals; they’re a necessary byproduct of this important function, much like any production process creates some amount of “trash.”
Free radicals, however, have a dark side: They can attack and damage healthy tissue and cells just as readily. The good news is that your body has the ability to keep them in check with what are called antioxidants: Compounds that your body either makes or that it gets from what you consume (food or herbs). Antioxidants “donate” electrons to the free radicals, neutralizing them before they can do too much indiscriminate damage to healthy cells and tissue.
In a perfect world, your body maintains a good balance of free radicals and antioxidants, which allow the former to do their important work without causing too much collateral damage. Unfortunately, most of us don’t live in a perfect world. Psychological stress, a carb-heavy and plant-deficient diet, environmental toxins, lack of sleep, and other things can tip the scales, leading to an excess of free radicals.
That’s where phytochemicals come in. Most if not all phytochemicals are potent antioxidants. They differ in the mechanism or route they use to reduce free radicals, but in general, phytochemicals serve the function of neutralizing them or reducing their production. Pterostilbene, for example, is an uncoupling agent, meaning it can temporarily detach machinery in our mitochondria that can cause it to overproduce free radicals.
Inflammation in the body is often the result of free radical activity or tissue damage. It’s a normal and healthy function, however, as with free radicals, it can end up “burning” out of control and become chronic, causing significant damage and contributing to heart disease, diabetes and other conditions.
Phytochemicals are known to fight or reduce inflammation in a variety of ways. For example, they may help regulate inflammatory cytokines (proteins released by cells that promote inflammation) or the gene expressions involved in that response. Resveratrol, a known anti-inflammatory, works in several ways, including by helping regulate the activity of COX-1 and COX-2 (enzymes involved in inflammation and that are the targets of ibuprofen) and lowering levels of IL-6, a pro-inflammatory cytokine.
Just as a plant’s phytochemicals help suppress pathogenic microbes and work to maintain a balanced and healthy microbiome — the collection of microbes we house in our bodies — for the plant itself, it can do the same for us humans. For example, various phytochemicals may damage or change a bacteria’s protective membrane in some way.
That’s the case for phenyl isothiocyanate, a type of glucosinolate, which are found in plants like cabbage, mustard and broccoli. One study found that it has a direct effect on e.coli. Other phytochemicals, meanwhile, may directly attack a microbe’s cells or its ability to reproduce; or suppress or neutralize the toxic substances it releases, reducing its harmful activity.
Phytochemicals are also known to interfere with various stages of cancer development by, say, neutralizing cancer-causing agents or shutting down cancer cells before they develop into tumors. Some also help strengthen or augment your own immune system, helping it better fight against cancer cells.
Various phytochemicals in medicinal mushrooms, for example, including triterpenoids and polysaccharides found in reishi mushrooms, have been shown to be potent weapons in the fight against cancer. One study in patients with lung cancer found that polysaccharides in reishi bolstered their immune response by helping to maintain the activity of specialized cancer-fighting cells called lymphocytes.
Numerous phytochemicals have been shown to benefit heart health and keep blood vessels and arteries healthy. Aside from the protective effect their antioxidant power provides, they may reduce circulating levels of cholesterol or maintain smooth and flexible linings of vessels.
Meanwhile, hawthorn, a flowering shrub in the rose family, is a well-known herbal remedy for cardiovascular health. It helps dilate coronary blood vessels, easing blood flow and lowering blood pressure. More specifically, it contains phytochemicals in the terpenoid and flavone families, as well as others, that help improve blood viscosity. One study suggests that its phytochemicals reduce platelets from clustering, allowing blood to flow more freely.
Phytochemicals are also known to work in many (many!) other ways to support our body’s functions and keep us healthy, including by sensitizing the body to insulin or controlling blood glucose, as well as by helping liver or cognitive function.
Consider anthocyanins: They’re known to do all of the above, as well as protect DNA, increase production of cytokines in ways that help regulate the immune system, and more. So it makes sense that they’ve been linked to positive outcomes or reduced risk for cardiovascular and neurodegenerative diseases, metabolic disorders like diabetes, obesity, cancer, and much more.
But, to go back to my point about phytochemicals being team players, one paper specifically noted that anthocyanins have been “notoriously difficult to study” in part because they frequently interact with other phytochemicals in ways that improve or increase their effects. What’s more, the mere act of trying to extract and isolate the compounds from their natural “bioactive mixture” can potentially degrade or interfere with their activity.
So while it can be useful to study individual phytochemicals in the lab to try to understand their specific activity or mechanisms of action, in practice, we may never fully understand or pinpoint their incredible power unless we consider the whole plant or plant extracts. Phytochemicals are not like drugs, where you can point to one molecule or pluck out one active compound in order to target one specific ailment or action.
Indeed, when using certain phytochemicals for our benefit, isolating may never work as well or provide the same benefits as consuming the whole food, plant, herb, or herbal extract. Beta carotene is a prime example: Research has widely shown that a diet rich in food sources that contain the carotenoid (along with other naturally synergistic phytochemicals) can lower your risk for heart problems (among other things). And yet taking supplements containing isolated beta carotene actually showed a small but significant increase in mortality and a slight increase in cardiovascular death, according to a report from the Cleveland Clinic.
Herbs Deliver Where Food Falls Short
Even as we learn just how beneficial phytochemicals are for our health — and how they’re most effective in their whole, natural forms — we can’t forget that fruits and vegetables don’t contain the levels and variety of phytochemicals they used to. And perhaps that wouldn’t be so concerning if it weren’t for the fact that we’re all now living in a world that’s taking us into uncharted territory in terms of health risks.
For instance, our exposure to new and different environmental toxins and chemicals and chemicals in foods tax or disrupt our systems in ways that may negatively impact our health. Between 1970 and 1995, the amount of synthetic chemicals in use tripled, and experts say it’s continued to rise since then. In fact, data suggest there may be as many as 84,000 different chemicals in use, and it’s estimated that 96% of all manufactured materials and products today contain chemicals.
Research has also shown we’re more stressed today than our parents were at our age. Plus, we’re getting less sleep and exercise than ever before, and we tend to have a less diverse array of beneficial microbes in our bodies.
As a result of all these modern-day stress factors, everything from digestion to mental state to immune system health are suffering, and rates of chronic disease are exploding. Six in 10 Americans currently have at least one chronic disease and four in 10 have two or more (including heart disease, cancer, diabetes and Alzheimer’s), according to the CDC. And trends and experts suggest the numbers are likely to increase as our population ages.
The point is, if ever there were a time when we absolutely could use the extra insurance, support, activity, and power that phytochemicals deliver, it’s now. And thankfully, therapeutic herbs and medicinal mushrooms are still as loaded with phytochemicals as ever.
Why have herbs retained their rich phytochemical stores? Because they haven’t been cultivated and bred for taste, carbohydrate content, or mass production. Which means herbs may get us closer to replicating the phytochemical-loaded diets — and the health-giving results that our ancestors enjoyed even as recently as a few generations ago.
In fact, herbal supplements could deliver more phytochemicals than even an ancient foraged-food diet did. The reason: New technologies enable us to separate the synergistic phytochemicals from the bulky fiber of the plant and concentrate them in greater amounts.
Do herbs deliver the same phytochemicals you get from food? Yes and no — which is a good thing. Just as you want to eat a range of different foods in order to get a range of different nutrients and phytochemicals, herbs provide a wide range of phytochemicals with different activity and actions than you’d get from food.
Just consider one of the main reasons herbs contain the phytochemicals they do: For protection from the elements. So if you’re taking an herb like rhodiola, which grows in even the coldest climates (including Siberia), it’s going to contain specific phytochemicals, such as rosavin, salidroside, and others that help the plant withstand even the harshest environmental stressors, which many foods cannot endure.
And those are unique from what you get from, say, a fruit or plant native to tropical climates for which microbes are the biggest threat and whose phytochemicals then might excel at balancing your body’s microflora. Overall, getting a diverse range of phytochemicals from a wide variety of sources — both herbs and food — helps you get both enough and a broad spectrum of beneficial compounds and benefits.
Why Phytochemicals are Silent and Steady Superheroes
For all of their incredible health-promoting powers, phytochemicals — whether from food or herbs or both — are stealth in their actions. Again, they’re not like drugs, where you pop a pill and pretty quickly feel an effect or notice a difference or change.
Instead, change is usually gradual, and if you start out feeling relatively healthy, it can be subtle. But what I’ve found over the years, both in my own experience and from what I’ve heard from patients and others, is that you don’t realize all the good these phytochemicals are doing until you stop getting them — until you stop taking herbs or stop eating as many plant foods.
Good health tends to be something people take for granted until it’s gone. We don’t take notice until we start to feel a little off or more sluggish than usual. Or until even more blatant issues crop up, such as getting sick more often, allergies flaring more readily, or cholesterol or blood sugar ticking up over the years.
That’s where phytochemicals can play an integral role, acting as both an insurance policy and investment in your health and your future. They’ve been supporting human life since the beginning, and, particularly in the face of the new challenges and threats to our health that we all face. And they’ll do the same now — so long as you give them the opportunity and make up for what’s missing by adding phytochemical-rich herbs to your life.
For more information on wellness, Learn about
Dr. Rawls’ NEW book The Cellular Wellness Solution, at CellularWellness.com
1. Harvard University Medical School. “Fill up on phytochemicals.” Harvard Health Letter. 2019, February. Retrieved from https://www.health.harvard.edu/staying-healthy/fill-up-on-phytochemicals
2. Probst YC, Guan VX, Kent K. “Dietary phytochemical intake from foods and health outcomes: a systematic review protocol and preliminary scoping.” BMJ Open. 2017;7(2):e013337.
3. Salehi, Bahare et al. “Resveratrol: A Double-Edged Sword in Health Benefits.” Biomedicines. 2018 Sep; 6(3): 91.
4. Scripsema, Nicole K., Dan-Ning Hu and Richard B. Rosen. “Lutein, Zeaxanthin, and meso-Zeaxanthin in the Clinical Management of Eye Disease.” J Ophthalmol. 2015; 2015: 865179.
5. Kim, Jae Kwank and Sang Un Park. “Current potential health benefits of sulforaphane.” EXCLI Journal. 2016; 15: 571–577.
6. Lee, M.T., et al. “Antioxidant capacity of phytochemicals and their potential effects on oxidative status in animals — A review.” Asian-Australas J Anim Sci. 2017 Mar; 30(3): 299–308.
7. Lobo, V., A. Pati, A. Phatak, and N. Chandra. “Free radicals, antioxidants and functional foods: Impact on human health.” Pharmacogn Rev. 2010 Jul-Dec; 4(8): 118–126.
8. Zhu, Fengmei, Bin Du and Baojun Xu. “Anti-inflammatory effects of phytochemicals from fruits, vegetables, and food legumes: A review.” Critical Reviews in Food Science and Nutrition. 2018; 58(8): 1260-1270.
9. Barbieri, Ramona. “Phytochemicals for human disease: An update on plant-derived compounds antibacterial activity.” Microbiological Research. 2017, March; 196: 44-68.
10. Khameneh B, et al. “Review on plant antimicrobials: a mechanistic viewpoint.” Antimicrob Resist Infect Control. 2019;8:118.
11. Mickymaray, Suresh. “Efficacy and Mechanism of Traditional Medicinal Plants and Bioactive Compounds against Clinically Important Pathogens.” Antibiotics (Basel). 2019 Dec; 8(4): 257.
12. Abreu, Ana Cristina, Anabella Borges, Lucia Chaves Simoes, et al. “Antibacterial activity of phenyl isothiocyanate on Escherichia coli and Staphylococcus aureus. Med Chem. 2013 Aug; 9(5):756-61.
13. Upadhyay, Swapna and Madhulika Dixit. “Role of Polyphenols and Other Phytochemicals on Molecular Signaling.” Oxid Med Cell Longev. 2015; 504253.
14. PDQ Integrative, Alternative, and Complementary Therapies Editorial Board. Medicinal Mushrooms (PDQ®): Patient Version. 2020 Apr 21. In: PDQ Cancer Information Summaries [Internet]. Bethesda (MD): National Cancer Institute (US); 2002-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK424937/
15. Gao, Pinyi, Shuangshuang Li, Kechun Liu, et al. “ Antiplatelet aggregation and antithrombotic benefits of terpenes and flavones from hawthorn leaf extract isolated using the activity-guided method.” Food Funct. 2019 Feb 20;10(2):859-866.
16. Jamar, Giovana, Débora Estadella and Luciana Pellegrini Pisani. “Contribution of anthocyanin-rich foods in obesity control through gut microbiota interactions.” Biofactors. 2017 Jul 8;43(4):507-516.
17. Ferreira Reis, Jordano et al. “Action mechanism and cardiovascular effect of anthocyanins: a systematic review of animal and human studies.” Journal of Translational Medicine. 2016; 14: 315.
18. Medina dos Santos, Nathalia et al. “Current evidence on cognitive improvement and neuroprotection promoted by anthocyanins.” Current Opinion in Food Science. 2019, April. 26: 71-78
19. Lin, Bo-Wen et al. “Effects of anthocyanins on the prevention and treatment of cancer.” British Journal of Pharmacology. 2017 Jun; 174(11): 1226-1243.
20. Belwal, Tarun et al. “Dietary Anthocyanins and Insulin Resistance: When Food Becomes a Medicine.” Nutrients. 2017 Oct; 9(10): 1111.
21. Lila, Mary Ann. “Anthocyanins and Human Health: An In Vitro Investigative Approach.” J Biomed Biotechnol. 2004 Dec 1; 2004(5): 306–313.
22. Osganian, Stavroula K. et al. “Dietary carotenoids and risk of coronary artery disease in women.” The American Journal of Clinical Nutrition. 2003, June. 77(6): 1390–1399.
23. Lichtenstein, Alice H. “Nutrient supplements and cardiovascular disease: a heartbreaking story.” J Lipid Res. 2009 Apr; 50(Suppl): S429–S433.
24. Cleveland Clinic. “Antioxidants, Vitamin E, Beta Carotene, & Cardiovascular Disease.” April 22, 2019. Retrieved from: https://my.clevelandclinic.org/health/articles/16740-antioxidants-vitamin-e-beta-carotene–cardiovascular-disease
25. Davis, Donald R. “Declining Fruit and Vegetable Nutrient Composition: What Is the Evidence?” https://journals.ashs.org/hortsci/view/journals/hortsci/44/1/article-p15.xml. 2009. 44(1): 15–19
26. Robinson, Jo. “Breeding the Nutrition Out of Our Food.” The New York Times. May 25, 2013. Retrieved from: https://www.nytimes.com/2013/05/26/opinion/sunday/breeding-the-nutrition-out-of-our-food.html
27. Medawar, Evelyn, et al. “The effects of plant-based diets on the body and the brain: a systematic review.” Translational Psychiatry. 2019, September. 9, 226.
28. Wallace, Taylor C. et al. “Fruits, vegetables, and health: A comprehensive narrative, umbrella review of the science and recommendations for enhanced public policy to improve intake.” Critical Reviews in Food Science and Nutrition. 2020. 60(13): 2174-2211.
29. Roundtable on Environmental Health Sciences, Research, and Medicine; Board on Population Health and Public Health Practice; Institute of Medicine. Identifying and Reducing Environmental Health Risks of Chemicals in Our Society: Workshop Summary. Washington (DC): National Academies Press (US); 2014 Oct 2. 2, The Challenge: Chemicals in Today’s Society. Available from: https://www.ncbi.nlm.nih.gov/books/NBK268889/
30. Centers for Disease Control and Prevention. “Chronic Diseases in America.” Retrieved from: https://www.cdc.gov/chronicdisease/resources/infographic/chronic-diseases.htm
31. Raghupathi, Wullianallur and Viju Raghupathi. “An Empirical Study of Chronic Diseases in the United States: A Visual Analytics Approach to Public Health.” Int J Environ Res Public Health. 2018 Mar; 15(3): 431.
32. Grace, Mary H. et al. “Phytochemical Characterization of an Adaptogenic Preparation from Rhodiola heterodonta.” Nat Prod Commun. 2009 Aug; 4(8): 1053–1058.