Peanut as a functional food(2),when to harvest peanuts

Peanut as a functional food(2)


Research has identified numerous compounds in peanuts and in their skins that may have added health benefits beyond basic nutrition. Peanuts have been touted as a functional food with numerous functional components like Coenzyme Q10 which protects the heart during the period of lack of oxygen example high altitudes and clogged arteries. peanuts are also a good source of dietary fiber and provide a wide range of essential nutrients, including several B group vitamins, vitamin E, minerals such as iron, zinc, potassium and magnesium, antioxidant minerals (selenium, manganese and copper), plus other antioxidant compounds (such as flavonoids and resveratrol) (Gulcin, 2010). These bioactive components have been recognized for having disease preventative properties and some are antioxidants while other is to promote longevity. The antioxidant capacity in peanut is due to the total biological matters in peanut seed such as vitamin E in oil or chlorogenic acid, caffeic acid, coumaric acid, ferulic acid, flavonoids and stilbene (resveratrol) (Yu et al, 2005). Fermented peanut meal (Zhang et al. 2011) has been used to study the antioxidant activity and free radical scavenging activity.

Bioactive components in Peanuts:


Arginine or L-arginine is an amino acid that is needed to keep the liver, skin, joints, and muscles healthy. Arginine helps to strengthen the body’s immune system, regulates hormones and blood sugar and promotes male fertility. In addition, research has shown that this amino acid may improve circulation and treat impotence and heart disease. Arginine is also considered as a semi-essential amino acid because, although the body manufactures its own supply, there are times when dietary supplementation may be required, such as in the case of severe wounds or illness. Food supplements rich in arginine (peanuts, equivalent to 1 g of arginine/day) or with a low arginine content (wheat crackers) to the smear positive pulmonary tuberculosis patients during four weeks was given, the primary outcome was cure rate according to the WHO classification and secondary outcomes were sputum smear conversion, weight gain, sedimentation rate, reduction of cough and chest X-ray improvement as well as levels of NO in urine (uNO) or exhaled air (eNO) at two months (T. Schön et al, 2011). In addition, newborns are not able to make their own supply of this substance, so arginine is considered essential in the first months of life.      Arginine stimulates the immune system by increasing the output of T lymphocytes (T- cells) from the thymus gland. Recent studies have focused on the potential of arginine in treatment of AIDS, cancer, and other diseases linked to a depressed immune system.  Arginine helps to detoxify the liver by neutralizing the effects of ammonia and other toxic substances in the body. Peanuts have the highest level of arginine among­­­ foods (USDA SR-21). Arginine is an amino acid that is a precursor to nitric oxide that helps to keep the arteries relaxed, improving blood flow and healing time in tissues in the body (Moncada and Higgs, 1993). In context of functional activity, Duggan et al. (2002) claimed arginine to be one of the protective nutrients for the gastro intestinal tract.



Resveratrol (3,4’,5-trihydroxystilbene) belongs to a class of polyphenolic compounds called stilbenes. Some types of plants produce resveratrol and other stilbenes in response to stress, injury, fungal infection, or ultraviolet (UV) radiation (Jeandet et al., 2002). Resveratrol is a fat-soluble compound that occurs in a trans and a cis configuration. Both cis- and trans-resveratrol also occur as glucosides (bound to a glucose molecule). Resveratrol-3-O-beta-glucoside is called piceid. Scientists became interested in exploring potential health benefits of resveratrol in 1992 when its presence was first reported in red wine, leading to speculation that resveratrol might help explain the “French Paradox”. More recently, reports on the potential for resveratrol to inhibit the development of cancer and extend lifespan in cell culture and animal models have continued to generate scientific interest (Linus Pauling Institute, micronutrient information center, 2008).

Peanuts are excellent source of resveratrol, a polyphenol antioxidant (Gulcin, 2010) which have been found to have protective function against cancers (Jang et al.,1997, Gagliano et al, 2000), heart disease (Goldberg,1995), degenerative nerve disease, Alzheimer’s disease (Chen, 2005),tumor (Bishayee et al., 2010) and inflammation (Kang et al. 2010)This bioflavonoid is believed to improve blood flow in the brain by much as 30%, thus reducing the risk of stroke (Athar, 2006). Besides theantioxidant properties that provide protection against cardiovascular diseases such as arteriosclerosis (Das et al., 1999), it has been demonstrated that resveratrol resveratrol acts as chemopreventive agent against several types of cancer by modulating tumour initiation, promotion and progression phases (Delmas, Lancon, Colin, Jannin, & Latruffe, 2006; Jannin et al., 2004). Moreover, resveratrol seems to extend the lifespan of diverse species including Saccharomyces cerevisiae, Drosophila melanogaster and mouse (Baur et al., 2006; Howitz et al., 2003; Valenzano et al., 2006).


All parts of the peanut contain resveratrol from the roots to the skin and even the shell (Chen, 2002; Francisco, 2008). Resveratrol content in peanut butter is very close to grape juice with about three times more resveratrol than roasted peanut with skins (Sobolev, 1999; Ibern-Gomez, 2000). Studies are now showing that stressing peanut in various ways, resveratrol content can be increased (Rudolf, 2006).



Phytosterols (referred to as plant sterol and stanol esters) are a group of naturally occurring compounds found in plant cell membranes. Because phytosterols are structurally similar to the body’s cholesterol, when they are consumed they compete with cholesterol for absorption in the digestive system. As a result, cholesterol absorption is blocked, and blood cholesterol levels reduced.

As part of a heart-healthy eating plan, consuming phytosterols in recommended quantities has been shown to lower total cholesterol up to 10 percent and LDL or “bad” cholesterol up to 14 percent. There is increasing evidence that the reintroduction of plant foods providing phytosterols into the modern diet can improve serum lipid (cholesterol) profiles and reduce the risk of cardiovascular disease.

Peanuts, peanut butter, peanut flour, and peanut oil are all filled with phytosterols (beta sitosterol, campesterols and stigmasterol) that block the absorption of cholesterol from the diet. (Lopes et al, 2011). Emerging evidence is showing that they also decrease the inflammation and reduce the growth of various cancers i.e lung, stomach, ovarian, prostrate, colon and breast cancer (Woyengo, 2009).in addition to the healthy fats, proteins and fibers in peanuts, phytosterols may also be contributing to the decrease risk of heart disease that has been shown in population groups who eat a small amount of peanut daily (Awad, 2000)

Phenolic acids 

Research clearly shows that peanuts and their skin are exceptional sources of functional compounds, including phenolic acids (Francisco, 2008-2009). Research studies have been shown that peanuts contains high concentrations of poly- phenolic antioxidants, primarily in p-coumaric acid levels, boosting it .overall antioxidant content by as much as 22%(Duncan et al (2006).They further elaborated that roasted peanut skin has greater antioxidant capacity than the roasted whole peanut Lopes et al (2011) have also described the role of phenolic acids as antioxidants



Flavonoids are in all parts of the peanut plants. A high intake of flavonoids is thought to be protective against heart disease and cancer by various mechanisms. Research in emerging as to how these bioactive compounds are benefiting health Peanuts and peanut butter are considered a major food source of flavonoids and contain same types found in green and black tea, apples red wine, and soybeans(Francisco et al, 2008)

Diabetes and blood sugar

Jiang et al.(2002) have reported reduced risks of diabetes by a quarter when peanuts were incorporated in diet on a daily basis .Magnesium (King DE, et al ,2007;He ,et al ,2006;Larsson and wolk,2007) and dietary fibers (Gartside and Glueck ,1995)have been attributed as the main contributory factors for improved health status.

The Glycemic Index is a numerical Index that ranks carbohydrates based on their rate of glycemic response (i.e. their conversion to glucose within the human body). Glycemic Index uses a scale of 0 to 100, with higher values given to foods that cause the most rapid rise in blood sugar. Pure glucose serves as a reference point, and is given a Glycemic Index (GI) of 100.

Your body performs best when your blood sugar is kept relatively constant. If your blood sugar drops too low, you become lethargic and/or experience increased hunger. And if it goes too high, your brain signals your pancreas to secrete more insulin. Insulin brings your blood sugar back down, but primarily by converting the excess sugar to stored fat. Also, the greater the rate of increase in your blood sugar, the more chance that your body will release an excess amount of insulin, and drive your blood sugar back down too low.

Therefore, when you eat foods that cause a large and rapid glycemic response, you may feel an initial elevation in energy and mood as your blood sugar rises, but this is followed by a cycle of increased fat storage, lethargy, and more hunger, that is why diabetic people are recommended of low GI food.



Inflammatory factors in the blood like C-reactive proteins (CRP) have been identified as predictors of cardiovascular disease. Dietary factors may play a role in reducing inflammation (Nettleton,2006).Certain fats , antioxidants ,dietary fiber, arginine, and magnesium are components that have been showed to help regulate inflammation (Salas-Salvado, 2007). A relationship has also been observed between frequent peanut consumption and reduced inflammatory factors (Jiang, 2006)



Unsaturated fats, certain vitamins and minerals, and the bioactive components have shown to have cancer-preventative effects, which are all packaged into a peanut kernel (Gonzalez, 2006) In particulars, the phytosterols in peanuts that have been studied in regards to cancer (Woyengo, 2009).they have been reported to reduce prostrate tumor growth by over 40 % and cut the occurrences of cancer spreading to other parts of the body by almost 50%9Awad, 2000; 2001). Like phytosterols, resveratrol has also been shown to cut off the blood supply to growing cancers and to inhibit cancer cell growth (Athar, 2006)

Gallstone disease

Gallstone disease occurs when there is too much cholesterol or bilirubin in the bile or when the gallbladder doesn’t empty correctly. Peanuts are known to have beneficial effects on cholesterol, primarily due to their unsaturated fats .As a complex plant food, however, peanuts contain additional nutrients and bioactive compounds that are also likely to be contributing to this effect .It has been found that those who eat peanuts and peanut butter five times a week or more have a reduced risk of gallbladder disease by as much as 25%(Tsai, 2004)

Alzheimer‘s disease 

Research published in the Journal of Neurology, Neurosurgery and Psychiatry indicates regular consumption of niacin-rich foods like peanuts provides protection against Alzheimer’s disease and age-related cognitive decline.

Peanuts have a high content of niacin and are an excellent source of vitamin E (Table 2),both of which have been shown to protect against Alzheimer ‘s disease and age-related cognitive decline In almost 4000 people 65 years or older ,niacin from food slowed the rate of cognitive decline (Morris,2003).It has also been found that the consumption of vitamin E from supplements had no effect on the incidence of Alzheimer’s, vitamin E intake from food has been was protected (Morris,2002).In those who were in the top fifth of intake, incidence of Alzheimer’s disease was reduced by 70%. Resveratrol has also been recognized as beneficial in Alzheimer’s disease and other nerve degeneration disease (Chen, 2005).

Peanuts and Weight Management

Considerable evidences show that incorporating peanut and peanut butter into the diet does not lead to weight gain or higher body weight (Mattes, 2008). In the research related to the weight loss, diets incorporated with peanuts, peanut butter and peanut oil have more acceptability amongst the subjects of all age groups and have shown to provide long term weight maintenance (McManus, 2001). In another research exclusively on school children it was found that there was weight loss in peanut fed group whereas the control group gained weight in a span of 2 years(Johnston,2007:Johnston,2009). Similar data has been published in many more epidemiological studies where it was found that peanuts reduced the total and LDL cholesterol (Pelkman, 2004: Ob’Byrne, 1997: Shai, 2008).

Hunger maintenance

Research data show that peanut and peanut butter consumption improved the feeling of fullness and satisfied the consumers better than the carbohydrates snacks like rice cakes in equal quantities (Kirkmeyer, 2000).Another study showed that peanut consumption curbed the appetites of the subject due its fullness effect (Alpher, 2003).Emerging evidence is also showing that the type of healthy monounsaturated fat in peanuts may stimulate a hormone that helps to feel satisfied after consumption (Schwartz,2008).

Body mass index (BMI)

Peanut and peanut butter eaters tend to have a lower body mass index (BMI) (Sabate ,2007;Fraser ,1992;Hu,1998 ;USDA). Alpher and Mattes ,(2002)showed that despite being energy dense ,peanuts have a high satiety value and chronic ingestion evokes strong dietary compensation and little changes in energy balance .The mechanism behind this conversation could be enhanced satiety (Holt et al ,1995;Kirkmeyer and mattes 2000;Burton –Freeman,2000) the hunger and  energy  compensation (Kirkmeyer and Mattes ,2000)inefficient absorption of whole peanuts (Levine and Silvis , 1980) or increased resting energy expenditure (Mensink et al ,1997).


Peanut milk although not very popular is used extremely in cases of emergencies and malnutrition for rapid recovery and gain of health. In the past Peanut based product like “Plimpy-nut”, a RUTF (Ready-to-Use Therapeutic Food) has been formulated to overcome severe malnourishment in the African nations. It is a lipid based mix containing ground, roasted peanuts. In addition, vegetable oil, powdered milk, vitamins, minerals, and sugar are added. Peanuts as the basis for RUTF enable better delivery of a full range of balanced lipids, essential amino-acids, minerals and vitamins required by developing children. Peanuts are calorie and nutrient-dense, and protein-rich, ideal for small stomachs in malnourished children who can only take in small amounts. Their African nations like Malawi, Sudan and Haiti, treatment with RUTF in children has repeatedly shown superior recovery rates and shorter duration to reach weight-to-growth goals compared to standard World Health Organization (WHO) therapies for malnutrition rehabilitation (Patel et al.,2005) in 2003, Diop, et al.(2009) showed that moderately malnourished RUTF-users had higher intake of energy, fat, iron and zinc compared to a group consuming corn/soy therapy because the consumption of staple foods fell in the corn/soy group. Both therapies resulted in modest weight pain, but the effect lasted longer for the RUTF group.

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