Health News of Tuesday, 15 November 2022

Source: College of Holistic Medicine

Yams enhance brain function, ease symptoms of menopause

Yam Yam

One study by (Chandrasekara and Kumar, 2016) explained that yams (Dioscorea) are a type of tuber vegetable that originated in Asia, Africa, and the Caribbean. About 95% of yams today are grown in Africa. History has it that yams got their name from the Fulani (a language spoken in Guinea, West Africa) word nyami, which means “to eat.”

Yams come in white, yellow, purple, or pink flesh. In Ghana, there are many varieties of white yam, but the most important ones include Puna, Lariboko, Denteh (Punjo), Asana, and Araba.

The color depends on the maturity of the yam. White yams are high in potassium, while yellow, orange, and purple flesh yams are full of antioxidants, complex carbohydrates, and vitamins. They have a ton of health benefits. For example, they are a source of resistant fiber, which makes them an ideal food option for digestion and weight loss. Yams help prevent spikes in blood sugar after a hearty meal. In addition, they have several other qualities that make them nutritious.

Types of yams grown:

Indian yam (D. trifida)
Winged or water yam (D. alata)
Guinea yam (D. rotundata)
Yellow Guinea yam (D. cayenensis)
Lesser yam (D. esculenta)
Chinese yam (D. polystachya), also known as cinnamon vine

Yam Nutrition Facts

Indian yam (D. trifida)
Winged or water yam (D. alata)
Guinea yam (D. rotundata)
Yellow Guinea yam (D. cayenensis)
Lesser yam (D. esculenta)
Chinese yam (D. polystachya), also known as cinnamon vine

Yam Nutrition Facts

Two studies (Weaver, C.M, 2013; Aschner and Dorman, 2006) also found that apart from the rich fiber content in yam, it is also high in potassium and manganese, which play an important role in aiding bone health, growth, metabolism, and heart function. Yams also provide good amounts of other micronutrients, such as copper and vitamin C.

For instance, four studies (Collins and Klevay, 2011; National Academy of Sciences (US) and National Research Council (US) Division of Medical Sciences.

Conference on Hemoglobin: 2–3 May 1957. Washington (DC): National Academies Press (US); 1958; Padayatty et al, 2003; Chambial et al. 2013) found that Copper plays a significant role in red blood cell production and iron absorption, on the other hand, vitamin C acts as a strong antioxidant that can boost your immune system.

Yams, Science

Support brain function


Studies have linked the consumption of yams to brain support. For instance, Tohda et al.(2017) 12-week study, used respondents who took a yam extract supplement and found that they recorded advanced brain function tests as compared to the placebo group.

The reason why the participants experienced such a higher brain function was attributed to the specific compound in yam called diosgenin, which has been found to promote neuron growth and boost brain function.

In animal studies (Chiu et al, 2011) diosgenin has been found to enhance memory and learning abilities in mice in various maze tests. Studies are still ongoing to examine how the consumption of yams improves brain health.

Yams, menopause
Studies have also been conducted on yams and found that it aids some symptoms of menopause. For instance, (Wu et al. 2015), employed a 30-day study, where 24 postmenopausal women shifted from their normal rice consumption and focused on eating yams in 2 out of 3 meals (390 grams total) per day. The study found that their blood levels of estrone and estradiol increased by 26% and 27%, respectively.

Two studies (Santoro et al. 2015; Peacock et al. 2022) found that during menopause, blood levels of estrone and estradiol — two estrogen hormones — naturally decrease. Hence, anything that helps in restoring estrogen levels may ease menopause symptoms and yams do exactly that.

An earlier clinical trial by Komesaroff et al. (2011) conducted over a six-month found that topically applied wild yam cream had very little effect on menopause symptoms, such as flushing and night sweats, compared with a placebo. Still, more studies are ongoing to establish the role that yams could play in aiding menopause symptoms.

Yams, cancer-fighting properties

Studies have also been conducted to establish the cancer-fighting abilities of yams. For example, two studies (Hou et al. 2002; Son et al. 2014) found that yams are loaded with many antioxidants that could have anticancer properties.
For instance, two animal studies (Son et al. 2014; Shin et al. 2012) found that eating a yam-rich diet significantly decreased colon tumor growth.

How yams were found to decrease colon tumor growth was linked to antioxidants. This means, the more frequently we eat a yam diet, the more we are protected from cancer.

Apart from animal studies, two test-tube studies (Liu et al. 2016; Chiu et al. 2013) also found that extracts from Chinese yam, precisely the peel, inhibited liver tumor growth and aided antioxidant properties. More studies are needed to establish its effects on humans.

Yams, inflammation

Studies have also confirmed that the antioxidants in yams could decrease inflammation. For instance, three studies (Kolb and Mandrup-Poulsen, 2010; Pearson et al. 2003; Gregor and Hotamisligil, 2011) found that chronic inflammation is the foundation for increased risk of many illnesses, including heart disease, diabetes, and obesity.

Hence, human studies established that the consumption of yams as an anti-inflammatory food, could help avert chronic inflammation (Casas et al. 2014; Koloverou et al. 2012).

Also, four rat studies (Son et al. 2014; Chiu et al. 2013; Park et al. 2013; Chen et al. 2017) found that yam powder decreased inflammation linked to numerous illnesses, such as colon cancer, irritable bowel syndrome (IBS), and stomach ulcers.

Yams, blood sugar control

Studies have also confirmed that yam consumption could support blood sugar levels.

For instance, in one study (Go et al. 2015), rats were given yam powder or yam water extract and they had reduced fasting blood sugar and hemoglobin A1C (HbA1c) levels, juxtaposed with the control groups. HbA1c is a measure of long-term blood sugar control.

Another study (Helen et al. 2013) found that rats given higher amounts of purple yam extract experienced decreased appetites, greater weight loss, and better blood sugar control, juxtaposed with a control group.

Additionally, another study in rats (Harijono and Endang, 2016) found that complementing with yam flour, reduced the rate of blood sugar absorption, which led to better blood sugar control. These effects have been credited to the resistant starch and fiber in yams.

Birt et al. ( 2013) explained that resistant starch passes through your gut undigested. This type of starch is linked to various health benefits, including decreased appetite, as well as improved blood sugar levels, and insulin sensitivity.

Other benefits

Yams are associated with several other health benefits, including:

Digestive health.

Two studies (Li et al. 2019; Chen et al. 2003) found that the resistant
starch in yams may enhance digestion.
enzymes that help break down food and increase the number of good bacteria
in your gut.

Weight loss.

One animal study (Harijono and Endang, 2016) found that yam extract decreased food intake, signifying that these tubers could aid in reducing appetite and increasing weight loss. The fiber in yams could aid weight
loss.

Antimicrobial effects.

Two studies (Kelmanson et al. 2000; Kuete et al. 2012) found that yam extract may protect against certain drug-resistant bacteria.

Improved cholesterol levels.

In one study (Wu et al. 2005), women who ate 18 ounces (390 grams) of yams per day for 30 days had a 6% decrease in blood cholesterol levels.

Warnings

Yams contain compounds that are potentially toxic when eaten raw. Always cook yams before eating them, which also makes their starch easier to break down. If you’re following a low-glycemic diet or low-carb diet, limit the number of root veggies you consume.

Deep-frying yams or eating with them lots of added sugar is not advisable. Boiling, roasting, or baking them with a bit of avocado oil, herbs and spices are good for consumption.

Take home

Studies have confirmed the numerous benefits of eating yam specifically on brain function and menopausal health. Compared to refined grains, most root vegetables are also lower in calories and lower on the glycemic index, which means they won’t spike your blood sugar as much. The fiber in starchy veggies slows down the release of glucose (sugar), which is important for energy and insulin balance.

Additionally, plant foods that contain fiber have been shown to promote gut health and exhibit other beneficial activities, including anti-carcinogenic, anticoagulant, and immune-stimulating and antioxidant effects. A high-fiber diet not only helps prevent inflammation and disease formation, but it also works wonders for helping with digestion and preventing IBS or naturally relieving constipation.


NB:

Prof. Nyarkotey has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations to justify his write-ups. My articles are for educational purposes and do not serve as Medical advice for Treatment. I aim to educate the public about evidence-based scientific Naturopathic Therapies.

The writer is a Professor of Naturopathic Healthcare, President, of Nyarkotey College of Holistic Medicine & Technology (NUCHMT)/African Naturopathic Foundation. E-mail: collegeofholisticmedicine@gmail.com.

References


Weaver CM. Potassium and health. Adv Nutr. 2013 May 1;4(3):368S-77S. doi: 10.3945/an.112.003533. PMID: 23674806; PMCID: PMC3650509.
Aschner M, Dorman DC. Manganese: pharmacokinetics and molecular mechanisms of brain uptake. Toxicol Rev. 2006;25(3):147-54. doi: 10.2165/00139709-200625030-00002. PMID: 17192121.
Collins JF, Klevay LM. Copper. Adv Nutr. 2011 Nov;2(6):520-2. doi: 10.3945/an.111.001222. Epub 2011 Nov 3. PMID: 22332094; PMCID: PMC3226389.
National Academy of Sciences (US) and National Research Council (US) Division of Medical Sciences. Conference on Hemoglobin: 2–3 May 1957. Washington (DC): National Academies Press (US); 1958. THE ROLE OF COPPER IN ERYTHROPOIESIS. Available from: https://www.ncbi.nlm.nih.gov/books/NBK224294
Padayatty SJ, Katz A, Wang Y, Eck P, Kwon O, Lee JH, Chen S, Corpe C, Dutta A, Dutta SK, Levine M. Vitamin C as an antioxidant: evaluation of its role in disease prevention. J Am Coll Nutr. 2003 Feb;22(1):18-35. doi: 10.1080/07315724.2003.10719272. PMID: 12569111.
Chambial S, Dwivedi S, Shukla KK, John PJ, Sharma P. Vitamin C in disease prevention and cure: an overview. Indian J Clin Biochem. 2013 Oct;28(4):314-28. doi: 10.1007/s12291-013-0375-3. Epub 2013 Sep 1. PMID: 24426232; PMCID: PMC3783921.
Tohda C, Yang X, Matsui M, Inada Y, Kadomoto E, Nakada S, Watari H, Shibahara N. Diosgenin-Rich Yam Extract Enhances Cognitive Function: A Placebo-Controlled, Randomized, Double-Blind, Crossover Study of Healthy Adults. Nutrients. 2017 Oct 24;9(10):1160. doi: 10.3390/nu9101160. PMID: 29064406; PMCID: PMC5691776.
Chiu CS, Chiu YJ, Wu LY, Lu TC, Huang TH, Hsieh MT, Lu CY, Peng WH. Diosgenin ameliorates cognition deficit and attenuates oxidative damage in senescent mice induced by D-galactose. Am J Chin Med. 2011;39(3):551-63. doi: 10.1142/S0192415X11009020. PMID: 21598421.
Wu WH, Liu LY, Chung CJ, Jou HJ, Wang TA. Estrogenic effect of yam ingestion in healthy postmenopausal women. J Am Coll Nutr. 2005 Aug;24(4):235-43. doi: 10.1080/07315724.2005.10719470. PMID: 16093400.
Santoro N, Epperson CN, Mathews SB. Menopausal Symptoms and Their Management. Endocrinol Metab Clin North Am. 2015 Sep;44(3):497-515. doi: 10.1016/j.ecl.2015.05.001. PMID: 26316239; PMCID: PMC4890704.
Peacock K, Ketvertis KM. Menopause. [Updated 2022 Feb 2]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK507826/
Komesaroff PA, Black CV, Cable V, Sudhir K. Effects of wild yam extract on menopausal symptoms, lipids and sex hormones in healthy menopausal women. Climacteric. 2001 Jun;4(2):144-50. PMID: 11428178.
Hou WC, Hsu FL, Lee MH. Yam (Dioscorea batatas) tuber mucilage exhibited antioxidant activities in vitro. Planta Med. 2002 Dec;68(12):1072-6. doi: 10.1055/s-2002-36356. PMID: 12494332.
Son IS, Lee JS, Lee JY, Kwon CS. Antioxidant and Anti-inflammatory Effects of Yam (Dioscorea batatas Decne.) on Azoxymethane-induced Colonic Aberrant Crypt Foci in F344 Rats. Prev Nutr Food Sci. 2014 Jun;19(2):82-8. doi: 10.3746/pnf.2014.19.2.082. PMID: 25054106; PMCID: PMC4103732.
Shin MY, Cho YE, Park C, Sohn HY, Lim JH, Kwun IS. The supplementation of yam powder products can give the nutritional benefits of the antioxidant mineral (cu, zn, mn, fe and se) intakes. Prev Nutr Food Sci. 2012 Dec;17(4):299-305. doi: 10.3746/pnf.2012.17.4.299. PMID: 24471100; PMCID: PMC3866735.
Liu Y, Li H, Fan Y, Man S, Liu Z, Gao W, Wang T. Antioxidant and Antitumor Activities of the Extracts from Chinese Yam (Dioscorea opposite Thunb.) Flesh and Peel and the Effective Compounds. J Food Sci. 2016 Jun;81(6):H1553-64. doi: 10.1111/1750-3841.13322. Epub 2016 Apr 27. PMID: 27122252.
Chiu CS, Deng JS, Chang HY, Chen YC, Lee MM, Hou WC, Lee CY, Huang SS, Huang GJ. Antioxidant and anti-inflammatory properties of Taiwanese yam (Dioscorea japonica Thunb. var. pseudojaponica (Hayata) Yamam.) and its reference compounds. Food Chem. 2013 Nov 15;141(2):1087-96. doi: 10.1016/j.foodchem.2013.04.031. Epub 2013 Apr 18. PMID: 23790890.
Pearson TA, Mensah GA, Alexander RW, Anderson JL, Cannon RO 3rd, Criqui M, Fadl YY, Fortmann SP, Hong Y, Myers GL, Rifai N, Smith SC Jr, Taubert K, Tracy RP, Vinicor F; Centers for Disease Control and Prevention; American Heart Association. Markers of inflammation and cardiovascular disease: application to clinical and public health practice: A statement for healthcare professionals from the Centers for Disease Control and Prevention and the American Heart Association. Circulation. 2003 Jan 28;107(3):499-511. doi: 10.1161/01.cir.0000052939.59093.45. PMID: 12551878.
Gregor MF, Hotamisligil GS. Inflammatory mechanisms in obesity. Annu Rev Immunol. 2011;29:415-45. doi: 10.1146/annurev-immunol-031210-101322. PMID: 21219177.
Casas R, Sacanella E, Urpí-Sardà M, Chiva-Blanch G, Ros E, Martínez-González MA, Covas MI; Rosa Ma Lamuela-Raventos, Salas-Salvadó J, Fiol M, Arós F, Estruch R. The effects of the mediterranean diet on biomarkers of vascular wall inflammation and plaque vulnerability in subjects with high risk for cardiovascular disease. A randomized trial. PLoS One. 2014 Jun 12;9(6):e100084. doi: 10.1371/journal.pone.0100084. PMID: 24925270; PMCID: PMC4055759.
Koloverou E, Panagiotakos DB, Pitsavos C, Chrysohoou C, Georgousopoulou EN, Grekas A, Christou A, Chatzigeorgiou M, Skoumas I, Tousoulis D, Stefanadis C; ATTICA Study Group. Adherence to Mediterranean diet and 10-year incidence (2002-2012) of diabetes: correlations with inflammatory and oxidative stress biomarkers in the ATTICA cohort study. Diabetes Metab Res Rev. 2016 Jan;32(1):73-81. doi: 10.1002/dmrr.2672. Epub 2015 Jul 27. PMID: 26104243.
Park JM, Kim YJ, Kim JS, Han YM, Kangwan N, Hahm KB, Kim TS, Kwon O, Kim EH. Anti-inflammatory and carbonic anhydrase restoring actions of yam powder (Dioscorea spp) contribute to the prevention of cysteamine-induced duodenal ulcer in a rat model. Nutr Res. 2013 Aug;33(8):677-85. doi: 10.1016/j.nutres.2013.05.019. Epub 2013 Jul 8. PMID: 23890358.
Chen T, Hu S, Zhang H, Guan Q, Yang Y, Wang X. Anti-inflammatory effects of Dioscorea alata L. anthocyanins in a TNBS-induced colitis model. Food Funct. 2017 Feb 22;8(2):659-669. doi: 10.1039/c6fo01273f. PMID: 28121001.
Go HK, Rahman MM, Kim GB, Na CS, Song CH, Kim JS, Kim SJ, Kang HS. Antidiabetic Effects of Yam (Dioscorea batatas) and Its Active Constituent, Allantoin, in a Rat Model of Streptozotocin-Induced Diabetes. Nutrients. 2015 Oct 15;7(10):8532-44. doi: 10.3390/nu7105411. PMID: 26501316; PMCID: PMC4632431.
O. Helen, Aluko Esther Olusola(2013) Dioscorea alata L. Reduces Body Weight by Reducing Food Intake and Fasting Blood Glucose Level. British journal of medicine and medical research. DOI:10.9734/BJMMR/2013/3791Corpus ID: 52108022
Harijono and Endang, (2016) Hypoglycemic Effect of Modified Water Yam Flour ( Dioscorea alata ) on Diabetic Wistar Rats ( Rattus norvegicus ) Journal of Food and Nutrition Research. DOI:10.12691/JFNR-4-1-4Corpus ID: 53328610
Birt DF, Boylston T, Hendrich S, Jane JL, Hollis J, Li L, McClelland J, Moore S, Phillips GJ, Rowling M, Schalinske K, Scott MP, Whitley EM. Resistant starch: promise for improving human health. Adv Nutr. 2013 Nov 6;4(6):587-601. doi: 10.3945/an.113.004325. PMID: 24228189; PMCID: PMC3823506.
Li T , Teng H , An F , Huang Q , Chen L , Song H . The beneficial effects of purple yam (Dioscorea alata L.) resistant starch on hyperlipidemia in high-fat-fed hamsters. Food Funct. 2019 May 22;10(5):2642-2650. doi: 10.1039/c8fo02502a. PMID: 31025041.
Chen H, Wang C, Chang C-, Wang T. Effects of Taiwanese yam (Dioscorea japonica Thunb var. pseudojaponica Yamamoto) on upper gut function and lipid metabolism in Balb/c mice. Nutrition. 2003 Jul-Aug;19(7-8):646-51. doi: 10.1016/s0899-9007(03)00058-3. PMID: 12831952.
Kelmanson JE, Jäger AK, van Staden J. Zulu medicinal plants with antibacterial activity. J Ethnopharmacol. 2000 Mar;69(3):241-6. doi: 10.1016/s0378-8741(99)00147-6. PMID: 10722206.
Kuete V, Betrandteponno R, Mbaveng AT, Tapondjou LA, Meyer JJ, Barboni L, Lall N. Antibacterial activities of the extracts, fractions and compounds from Dioscorea bulbifera. BMC Complement Altern Med. 2012 Nov 23;12:228. doi: 10.1186/1472-6882-12-228. PMID: 23176193; PMCID: PMC3528471.
Chandrasekara A, Josheph Kumar T. Roots and Tuber Crops as Functional Foods: A Review on Phytochemical Constituents and Their Potential Health Benefits. Int J Food Sci. 2016;2016:3631647. doi: 10.1155/2016/3631647. Epub 2016 Apr 3. PMID: 27127779; PMCID: PMC4834168.
Kolb H, Mandrup-Poulsen T. The global diabetes epidemic as a consequence of lifestyle-induced low-grade inflammation. Diabetologia. 2010 Jan;53(1):10-20. doi: 10.1007/s00125-009-1573-7. Epub 2009 Nov 5. PMID: 19890624.