The wonderful, often unknown fruits of nature
Many years ago, I have written a blog article on 'superfoods' that was later updated in 2018:
Even though, the term 'superfood' is not a legally-recognised word, and so is no longer in use, I still believe it is an amazing word to describe 'jewels' of nature. Untouched, fresh, ripe, antioxidant-rich plant foods have therapeutic effects on the body.
It is for this very reason that naturally growing foods (herbs, fruits and vegetables) are considered medicine, because of their direct on our body. It is evident that such foods play a key role in our health and energy. It is thus seen as calories, the power these foods hold to sustain our life.
But again, not all plant foods are equal. Not only in the way they are grown (e.g., conventionally, like GMOs, pesticide-drenched, grown with synthetic (man-made chemical) fertilisers, or organically, or even biodynamically), but also their molecular structure. For example, studies abound to show that some berries, including wild blueberries and açaí berries, and some fruits like citrus fruits and other nutrient-rich fruits like physalis, kiwi fruits, mangosteen, and a multitude more, as well as herbs have medicinal properties. This is in part due to their content in specific pigments (usually, stronger/darker the pigment, the higher the potency), compounds (naturally produced chemicals) or constituents (e.g., fibre).
There are 4 main families of pigments(1)
Each of these pigment categories englobes entire families of compounds within them, each with a unique name and colour, chemical structure and chemical properties, and unique effect on the body.(2)
Antioxidants and Health
Natural antioxidants are widely distributed in food and medicinal plants. These natural antioxidants, especially polyphenols and carotenoids, exhibit a wide range of biological effects, including anti-inflammatory, anti-aging, anti-atherosclerosis and anticancer. In biological system, reactive oxygen species (ROS) and reactive nitrogen species (RNS), such as superoxide, hydroxyl, and nitric oxide radicals, can damage the DNA and lead to the oxidation of lipid and proteins in cells. Normally, antioxidant system occurring in human body can scavenge these radicals, which would keep the balance between oxidation and anti-oxidation. Nonetheless, the exposure of cigarette smoking, alcohol, radiation, or environmental toxins induces the production of excessive ROS and RNS, which disrupt the balance between oxidation and anti-oxidation and result in some chronic and degenerative diseases.(3)
Oxygen is an essential chemical element in the metabolism of aerobic organisms. However, it may trigger unfavorable reactions, and there has been a growing interest in studying the role of its reactive species. Reactive oxygen species (ROS) include free radicals like the superoxide anion, singlet oxygen, lipid peroxides and the hydroxyl radical. These reactive species are by-products of the normal cellular energy production and functional activities, presenting an important role in cell signaling, apoptosis, gene expression and ion transportation. Nevertheless, if ROS levels increase intensely, it can result in damage of many molecules, including proteins, lipids, RNA and DNA, since they are highly reactive. Furthermore, the production of free radicals is not only associated with the normal metabolic processes in the human body (endogenous sources), but can also be due to environmental factors (exogenous sources) such as stress, ozone radiation, pollution, pesticides and industrial chemicals. When higher production of ROS in relation to their removal by biological systems (antioxidant defences) occurs, it is called oxidative stress. That has long been associated with increased risk for several diseases, such as cancer, diabetes, arthrosclerosis, arthritis, neurodegenerative diseases and premature ageing.(4)
Main families of antioxidants
Polyphenols are abundant in food and medicinal plants, including phenolic acids, flavonoids, lignans, and stilbenes.
Phenolic acids comprise of derivatives of cinnamic acid (e.g., p-coumaric, caffeic, and ferulic) and derivatives of benzoic acid (e.g., gallic acid and hydroxybenzoic acids).
Flavonoids are abundant in most edible fruits and vegetables. Its subclasses include flavonols, flavanones, catechins, flavones, anthocyanidins and isoflavonoids. The concentration and type of flavonoids vary in different dietary sources . Quercetin is usually the most abundant flavonol in edible plants. The richest dietary source of quercetin is onion.
Other flavonols include myricetin (berries), isorhamnetin (onion), and kaempferol (broccoli). Flavanones almost only exist in citrus fruits. Hesperidin and narirutin are the main flavonoids of oranges and mandarins, whereas, naringin and narirutin are the main flavonoids of grapefruit. Catechins usually exist in the form of aglycones or esterified with gallic acid. The richest dietary sources of catechins are tea and red wine. In addition, the major flavones are apigenin and luteolin. The major dietary sources are red pepper and celery. Anthocyanins, such as pelargonidin, cyanidin, and delphinidin, contribute to the red, blue, or violet color of edible plants, such as plums, eggplant, and many berries. The isoflavonoids, such as isoflavones genistein and daidzein, mainly exist in legumes. The richest dietary source are soybean and soy products.
The richest dietary source of lignans is linseed containing secoisolariciresinol and low quantities of matairesinol. Algae, leguminous plants (lentils), cereals (triticale and wheat), fruit (pears, prunes) and certain vegetables (garlic, asparagus, carrots) also have traces of these same lignans. Resveratrol is a stilbene, which has been extensively studied for its multiple bioactivities. Red wine is rich in resveratrol.
Carotenoids are natural pigments, including β-carotene, lycopene, lutein, and zeaxanthin . All colorful edible plants, especially dark green and yellow-orange leafy, are the good sources of carotenoids. Due to the lipid solubility of carotenoids, the absorption mainly depends on their preparation with oils or fats. Among the carotenoids, the β-carotene commonly occurs in edible plants that possesses the highest activity of provitamin A, such as acerola, mango, pumpkin, carrot, nuts, and oil palm. Lycopene is a kind of red pigment. It almost exists only in vegetables and algae.
A note on Synthetic (man-made) Antioxidants
Synthetic antioxidants have been used in place of natural ones, mainly because they present higher stability and performance, low costs and wide availability. The most referenced synthetic antioxidants in the food industry are butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), propyl gallate (PG) and tert-butyl hydroquinone (TBHQ). In addition, 2-naphthol (2NL), 4-phenylphenol (OPP) and 2,4-dichlorophenoxyacetic acid (2,4-DA) are the ones commonly used in fruits and vegetables.
Although synthetic antioxidants have been widely used, safety issues have been raised over time. There are several published studies indicating a relationship between the long-term intake of synthetic antioxidants and some health issues, such as skin allergies, gastrointestinal tract problems and in some cases increased the risk of cancer. High doses of synthetic antioxidants may cause DNA damage and induce premature senescence. BHA and BHT have already been found to be responsible for adverse effects on the liver and for carcinogenesis in animal studies. Additionally, very little is known about the environmental occurrence and fate of these compounds. (5,6,7,8,9)
Naturally-occurring antioxidants have been found to have a multitude of health benefits. (10)
It is, therefore, not surprising at all that some fruits and vegetables have been labelled 'superfoods' or nutrient-dense foods. The later, is the unanimously accepted term.
What nutrient-dense foods do you know?
Please, comment below...
Did you know that sprouted seeds are also considered nutrient powerhouses and so, qualify as nutrient-dense foods.
One of the most nutrient-dense food is purple broccoli sprout.
Another less-known nutrient powerhouse is Klamath Blue Green Algae. Contact me today for huge discount.
Look for our upcoming blogs on specific nutrient-dense, often unknown, plant foods.
Our first article is dedicated to jabuticaba.
Ever heard of it? Tasted it?
Personally, I haven't. But I can't wait to try it.
1. Chunxian C. (2015). Overview of Plant Pigments. In: Chunxian, C. Pigments in Fruits and Vegetables Genomics and Dietetics. New York : Springer Science+Business Media. ISBN 978-1-4939-2355-7.
3. Xu, DP. et al. (2017). Natural antioxidants in foods and medicinal plants: Extraction, assessment and resources. International journal of molecular sciences. 18(1), 96. https://doi.org/10.3390/ijms18010096
4. Lourenço, SC. Moldão-Martins, M. Alves, VD. (2019). Antioxidants of Natural Plant Origins: From Sources to Food Industry Applications. Molecules (Basel, Switzerland). 24(22): 4132. https://doi.org/10.3390/molecules24224132
5. Saad B. et al. (2007). Determination of synthetic phenolic antioxidants in food items using reversed-phase HPLC. Molecules. 105, pp. 389–394. doi:10.1016/j.foodchem.2006.12.025.
6. Xiu-Qin L. et al. (2009). Analysis of synthetic antioxidants and preservatives in edible vegetable oil by HPLC/TOF-MS. Food Chem. 113, pp. 692–700. doi:10.1016/j.foodchem.2008.07.072.
7. Jeong, SH. et al. (2005). Effects of butylated hydroxyanisole on the development and functions of reproductive system in rats. Toxicology. 208(1): pp. 49-62.
8. Botterweck, AA. et al. (2000). Intake of butylated hydroxyanisole and butylated hydroxytoluene and stomach cancer risk: results from analyses in the Netherlands Cohort Study. Food & Chemical Toxicology. 38(7): pp. 599-605.
9. Randhawa, S. Bahna, SL. (2009). Hypersensitivity reactions to food additives. Current Opinion in Allergy & Clinical Immunology. 9(3), pp. 278–283. doi:10.1097/aci.0b013e32832b2632
10. Chabert P. et al. (2014) Overview of Plant-Derived Antioxidants. In: Laher, I. (eds) Systems Biology of Free Radicals and Antioxidants. Springer, Berlin, Heidelberg. ISBN: 978-3-642-30017-2
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