Acute Effects of Nuts (Pecans and Walnuts) Ingestion on Plasma Level of Nutrients, Polyphenols and Biomarkers of Antioxidant Status

6 June 2016

The research was conducted for the reason that the researcher wanted to inform the audience on the effects of nuts ingestion to the plasma level of nutrients, polyphenols and biomarkers of antioxidant status.  Pecan nuts and walnuts are very popular nuts all over the world; however, these nuts are not sufficiently studied on the issues of the effect of ingestion on the plasma level of nutrients, polyphenols and biomarkers of the antioxidant status, all at the same time. It may have been studied but the effects on these nuts on the plasma level of nutrients, polyphenols and biomarkers of antioxidant status need more in-depth and expanded research.

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The postprandial effect of pecan nut and walnut ingestion to the plasma level of nutrients, polyphenolic compounds and biomarkers of the antioxidant status will also be explained. With this in-depth study, the audience will be able to understand the ingestion effects of the said nuts to their bodily functions. Evaluation on the effects of pecan nut and walnut consumption to the bioavailability of the polyphenols and antioxidant status in decreasing or lowering incidence of cardiovascular disease, neurodegenerative diseases and others, will help in the understanding the researched topic.

This will also include the role in maintaining oxidative balance which protects the body against diseases on in vivo changes in lipid peroxidation and antioxidant markers. Addtionally, the time trend of plasma total polyphenol level before and after pecan nuts and walnuts consumption in obtaining plasma peak concentration will also be tackled. Consequently, the audience will have a better understanding on these that will lead to healthier and happier living conditions. The benefits of these may be of good or bad, but with an in-depth learning process and understanding the audience will be able to maximize the good benefits of pecan nuts and walnuts and probably to other foods that are being ingested.


Pecan nuts or carya illinoences are very popular and are abundant since 8,000 years ago. Fossils of the nuts are found in streams and irrigations along Texas and some part of Mexico (Products-Pecans, 2004). Among the other nuts, pecans are the most valuable and the only nut that is naturally grown in North America. Pecan nuts are moniceous. The tree is self-fertilizing and hermaphrodite. It is closely related to hickories.

This nut contains allelopathic juglone which is toxic or poisonous to other plants (Ball, 2001). There are also several varieties of pecans according to their color, size and quantity of meat. Example of these varieties are; Cape Fear, Stuart, Mahan, Elliot, Mohawk, Gloria Grande, etc. Pecan nut sizes depend on the variety, age of tree, size of the crop and moisture condition. They thrive healthier in conditions on the southern part wherein there are long and warm days and nights. Pecans are said to be mature if the shuck loosens and the nut shell splits up and opens. They also get diseases.

Of the most common disease for pecan nuts is the scab that causes black spots in the leaves and nuts and malformation of the nuts (Pecan Trees, 2006). Its nutrition information indicates that pecan nuts are rich in fat, calories, potassium, magnesium, phosphorus, folate and other proximate, vitamins and minerals (Pecans, 2007).

Walnuts or juglans regia, on the other hand, are believed to originate in Persia which is cultivated in Europe, North America, North Africa and East Asia. Walnuts are deciduous trees and like pecans are also moniceous. There are several varieties of walnuts, example of these are; Hartley, Franquette, Payne and Eureka (Walnuts, 2007). Walnuts best thrive in

California wherein there are warm summers and cold winters. They are usually free from diseases and insects. Walnut nutritional information indicates that it is rich in calories, fat, potassium, magnesium, phosphorus, folate and other proximate, vitamins and minerals.

Pecan nuts and walnuts are said to be good sources of nutritional supplement needed by the body. Pecan nuts are rich source of oleic acid, a monosaturated fatty acid that helps in reducing bad cholesterol or LDL. It is also a good source of 19 vitamins and minerals, vitamin E, 18 essential amino acids, and fiber (Products-Pecans, 2004). It contains antioxidant properties which slows the oxidation of bad cholesterol. Pecans help in increasing vitamin E level that helps in the health of prostate and intestines. On the other hand, walnuts are rich in linoleic acid which contributes to the level of polyunsaturated fat in the body.

Polyunsaturated fat helps in reducing bad cholesterol in the body. However, large consumption of polyunsaturated fat can also reduce good cholesterol which consequently will lead to the reduction of the bad cholesterol (LDL) (Alberich, 2007, p. 2). Another good benefit of pecan nuts and walnuts is that they contain phytochemical called ellagic acid. Ellagic acids help in the triggering certain process, apoptosis, that helps in killing cancer cells by themselves (Ten Healthy Foods, 2002).

Nut consumption reduces the risk of cardiovascular disorders. Life expectancy is also prolonged without bouts of coronary problems (Alberich, 2007, p. 3). Pecan nuts is the best source of antioxidants, which in effect lowers the risk of heart diseases and certain cancers due to the presence of phytochemicals (Pecans and Your Health, 2007).

Research Questions

Are there any increase in plasma polyphenol concentration after consumption of pecan nuts and walnuts?
When is the peak concentration of polyphenols in plasma after consumption of pecan nuts and walnuts?
Is there an increase in plasma antioxidant capacity after consumption?

Literature Review

Pecan nuts and walnuts are the types of nuts that are prominent in America. These nuts are used in varied nut-containing meals. The pecan nut in particular, is an endemic tree in America. These nuts contain more than enough proximate, vitamins and minerals and other chemicals that in effect give good boost to the bodily functions. They are considered good food that helps reduce the risk of cardiovascular diseases, neurological diseases and certain cancers. Nuts like macadamia nuts, almonds, hazel nuts and peanuts are rich in monounsaturated fats while walnuts are rich in polyunsaturated fats.

Essentially, walnuts are rich in either N-3 and N-6 polyunsaturated fatty acids or PUFAs. Walnut consumption is said to reduce the plasma triglycerol and bad cholesterol (LDL) in the body (Almario, et al., 2001). Pecan nuts on the other hand, contain 60% polyunsaturated fatty acid and 30% monounsaturated fatty acids (Pecan Offers Good Nutrition, 2002).

Antioxidant is a substance that reduce oxidative damage that are caused by free radicals which are highly reactive that attacks molecules by capturing electrons that modifies chemical structure in the body (Medterms, 2007).

Pecan nuts and walnuts are said to be rich in antioxidants. According to the USDA Arkansas Children’s Nutrition Center, pecan nut has the highest antioxidant capacity among the nuts due to its significant content of vitamin E (Pecans FAQ, 2007). Pecan nut is rich in a particular vitamin E which is the gamma tocopherol. The vitamin E content of the pecan nut is said to have reduce the incidence of heart diseases. A study was conducted by the Loma

Linda University in California that had attested to the said proposition. It was conducted through a series of test involving 23 men and women ages 25 to 55. After the conduct of the study, it was confirmed that cholesterol-adjusted plasma gamma-tocopherol increased by 10.1% after eating pecan nut diet. The vitamin E content helps in the protection of fat content from oxidation of lipids by 7.4%.

Gamma-tocopherol and alpha-tocopherol have the same functions. They both affects low density lipoprotein oxidation, superoxide activity, platelet aggregation ox-LDL-mediated activation of nuclear factor-kappaB, apoptosis and arterial thrombogenesis. They also increase nitric oxide (NO) generation and activity of the enzyme NO synthase. Nevertheless, gamma tocopherol is more potent in all its functions and increases the cNOS protein expression (The Vitamin E Factor, 2007).

According to Dr. Ella Haddad (August 2006), lead author of the study, pecan consumption increases the gamma-tocopherol concentration in the blood, therefore, reduce lipid oxidation marker (Douaud, 2007). Another test result established in the observation is that certain phytochemicals found in pecan nuts protect the high level of unsaturated fats. It is self-protective due to high vitamin E or tocopherol content and complex phytonutrients with its ability to slow down oxidation process. Oxidation in the blood is harmful to one’s health because when the bad cholesterol was oxidized, it will build up and may result to arteriosclerosis (Pecan Nut-enriched Diet…, 2007).

Another study conducted by Wanda Morgan (March 2000) explains that the bad cholesterol (LDL), as well as the total cholesterol level decreases by 6% after consumption of pecan nuts. The outcome was concluded after the experimentation was conducted to 19 men and women with normal blood lipids level. The result showed that those who ingested pecan nuts – although consumed food with monounsaturated fats and polyunsaturated fats – did not gain weight and lowers the bad cholesterol and total cholesterol level in the body. Pecan nuts also increase the fiber nutrient intake in the body.

Heart–healthy diets with pecan nuts are said to help control specific biomarkers of the heart diseases effectively. It also increases level of dietary fiber, thiamine, magnesium, copper and manganese. Essentially, it transforms inadequate copper and magnesium intake to adequate. This observation and conclusion was presented by the Texas A&M University to the American Heart Association Conference on Arteriosclerosis, Thrombosis and Vascular Biology last May 2001.

Another research conducted by the University of Georgia concluded that plant sterols are natural in pecans, 90% of which are in the form of beta-sitosterol. Beta-sitosterol competes with the absorption of cholesterol in the body, therefore, lowers the blood

cholesterol level. Other health benefits of pecans are as follows; serving of 30g pecan nuts provide 25% more of oleic acid; it is cholesterol free; it is sodium-free; it is fiber-rich; it contains concentrated amount of sterols; and contains phytochemicals (Pecans Offer Good Nutrition, 2002). Furthermore, pecans are rich with vitamins and minerals including vitamin A, folic acid, calcium, phosphorus, potassium, vitamin B and zinc. It is also rich in high-quality protein that contains very few carbohydrates and no cholesterol.

In addition, pecan nuts aid in weight loss and maintenance due to increase metabolic rates and enhance satiety, according to the American Journal of Clinical Nutrition published in September 2003 (Pecans and Your Health, 2007). On the study based on the step I and II diets wherein the respondents are on a pecan-diet and control diet group, showed that the pecan-enriched group had lowered the thiobarbituric substance (TBARS) by 7.4% which indicates a non-plasma antioxidant effect (Nuts and Antioxidants, 2007).

Walnuts, on the other hand, contain sufficient substance that helps boost a healthy body, one of which is the presence of antioxidants. Many substances also contributed to the antioxidant activity brought about by the walnuts, these are the following: melatonin, ellagic acid, gamma tocopherol, carotenoids and polyphenolic compounds. (California Walnuts…, 2007).

Melatonin is a hormones in humans in the pineal glands. It is associated in inducing and regulating sleep. Amount of melatonin in walnut is said to be 2.5 to 45 nanograms per gram. In theory, melatonin in walnuts may reduce the incidence of cancer, delay or lessen severity of neurodegenerative diseases, and reduce severity of cardiovascular diseases (cited in Reiter, 2007).

With the high content of melatonin in walnuts, it was said that the level of resistance for oxidative stress caused by toxic molecules increases. Presence of antioxidants in walnuts reduces the oxidation level of bad cholesterol (LDL) and arteriosclerotic process. Because of walnut consumption, the risk of cardiovascular disease decreases due to the lowering of the cholesterol level (Salvado, 2002) and it also reduce several molecules that promotes arteriosclerosis. There are several positive effects that may be attributed to this. It lowers the  level of C-reactive protein, a marker of inflammation; it increases the level of protective omega 3 fatty acid eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA); and  decreases level of ICAM-1, VCAM-1 and E-selectin that are the components in the adhesion of the endothelium (Walnuts, 2007).

A study was conducted to prove that the walnuts are beneficial to the heart. On this study – comparing effects between Mediterranian diet to adjusted Mediterranian diet – it was proven that consuming monounsaturated-dense walnuts has favorable effects to the high cholesterol level and cardiovascular risks. It was also proven that the walnuts are rich in omega 3 essential fatty acids, and, walnuts are the only nut containing this health benefit. Omega 3 is beneficial to health because it prevents erratic heart rhythm, less susciptability to blood clots in the arteries, improves ratio of good cholesterol (HDL) against bad cholesterol (LDL) and reduce inflammation helpful in asthma, rheumatoid arthritis, and skin diseases

like eczema and psoriasis. Omega 3 is said to be a brain food . The brain contains 60% structural fats and this particular fat is actually found in the omega 3 of the walnuts. Some neurodegenerative diseases like Alzhiemer’s can be prevented by walnut intake, since this disease is caused by increasing inability of aging organism to protect from inflammation and oxidative stress. Walnut extract restrains amyloid-beta protein aggregation and breaks apart preformed aggregates. Two other components of walnuts, the ellagic acids and the gallic acids act as a dual-inhibitor of the enzyme acytelcholinesterase. Acytelcholine is a chemical in the brain responsible for the memory and learning. With Alzhiemer’s disease, acytelcholine is depleted (James, 2007).

Some epidemiological studies suggests that depression can be associated with the lowering of omega 3 content in the body and so with the association of ADHD in children to the low intake of omega 3 fatty acids.

This also help in the protection of the bones. Alpha-linolenic acid helps stabilize the ratio of omega 3 to omega 6 in the body which  prevents excessive bone turnover. Consuming omega 3-rich diet containing 17% polyunsaturated fatty acids, of which 10.5% is omega 6 and 6.5% is omega 3, resulted in the lower blood level of N-telopeptides, marker of bone breakdown, correlates with that of the marker of inflammation called necrosis factor-alpha (TNF-alpha).

Moreover, it was also proven that walnuts increases the artery elasticity by 64% and reduces the vascular cell adhesion molecules. Researchers also reported that consumption of walnuts increases flow in the bracial artery in the arm by 24%. Another substance beneficial  in the reduction in cardiovascular risk contributed by walnut consumption is the presence of L-arginine. L-arginine is an essential amino acid that is converted to nitric oxide (NO) which helps the inner walls of the arteries become smooth and allows it to relax (Walnuts, 2007).

Walnut consumption increases L-arginine 0.9 to 1.4 g/d. Endothelial functions increases without cardiovascular risks after L-arginine supplementation. It was explained that substituting walnuts for other monounsaturated fatty acids (MUFA) in the Mediterranian diet can be associated with the improved endothelial functions to people with hypercholesterolemia (Ros, et al, 2004). As to the hypocholesterolaemiant effect and increase in LDL-receptor activity, walnut is said to stabilizes the body weight and modifies the distribution of the  lipids between the various lipoproteins in the plasma without changes in the concentration of the plasmatic lipids (Alberich, 2007, p.6).

According to Cortes’s (2004) study, proving that walnuts which are rich in antioxidant, L-arginine, alpha-linolenic acid and omega 3, thus, has an acute favorable effect on vasoactivity and that postprandial endothelial function of the brachial artery and markers of oxidation and endothelial activiation. It was concluded that walnuts reverse the impairment of endothelial functions, positively affects postprandial vasoactivity and improved brachial artery vasoactivity. The experimentation also shows that vasoactivity can be attributed to the presence of other cardioprotective constituents of walnuts like the L-arginine, antioxidants and alpha-linolinec acid on the endothelial functions. Although walnuts are very rich in polyunsaturated fatty acids (PUFA), it does not promote lipid peroxidation.

Additionally, although walnuts are rich in vitamin E or gamma-tocopherol, it does not promote increase in plasma level after consumption. On the other hand, walnut consumption counteracted the detrimental changes in the flow mediated dilation (FMD) after consuming fatty foods. Increased in alpha-linolenic acid also improves the flow mediated dilation due to increased membrane fluidity of endothelial cells promoting enhanced synthesis and release of nitric oxide. Furthermore, unsaturated fatty acids and antioxidants in walnuts preserve the protective phenotype of the endothelial cells.

Ellagic acids which is present in both pecan nuts and walnuts play an important role in the antioxidation component of both nuts. Antioxidant mechanism of ellagic acids help in  scavenging of oxygen gas (O2), OH, peroxy radical, peroxynitrite, chemopreventive, antiviral,

and antibacterial. It enhances GSH-dependent protection. Additionally, it also decreases the activities of cytochrome P450 particularly CYP2E1, In vitro studies, ellagic acid is more potent than the alpha-tocopherol (Devipriya, et al. 2007, p.8). Ellagic acid is a polyphenolic compounds that prevents binding of carcinogens to DNA, strengthen connective tissues, it inhibits mutation within the cell’s DNA and ability to cause apoptosis or the self-annihilation of cancer cells (Ellagic Acid Cancer Treatment, 2007).

The highest or peak concentration of polyphenolic compounds in walnuts are found in the pellicle, the thin tan-brown skin that lines the meat of the nut.  Plasma polyphenols concentration in walnuts are basically rich in its kernel. It contains a number of nonflavaloid phenolics. English walnut pellicle extract contains at least ten plasma polyphenols, including ellagic acids, gallic acids, methyl gallate, etc. One serving of 50g of walnuts  extract contains 802 mg gallic acid equivalents (GEA) of phenols and 50g of pecan nuts extract contains 500 mg gallic acid equivalents (GEA). As per the assessment of Anderson, et al. (November 2001), walnut extract has more antioxidants than alpha-tocopherol and ellagic acid and gallic acid are more potent than alpha-tocopherol according to the trolox equivalent activity capacity (TEAC).

Difference between the extract and purified compounds can be explained by the presence phenolic compounds as complexes of hydrolyzable tannins that results in lower antioxidant activity and that it may contain compounds that do not have trolox equivalent activity capacity (TEAC) as high as purified ellagic acid or another thing is that antioxidant activity may be lost during extraction. Hydrolyzable tannins are metal complexing agents compared with simple ellagic acid. In some vivo studies, walnut consumptions reduces the bad cholesterol (LDL) and total cholesterol level, however, it does not change the LDL alpha-tocopherol level or resist oxidation when initiated ex vivo.

The favorable lipid profile pf walnuts had been propose as the mechanism for apparent antiatherogenic effect to humans. The fatty acids of walnuts are prone to oxidation where in fact the pellicle sorrounding the kernel is rich in antioxidant polyphenols and tocopherol in the kernel. Ten polyphenol is present in the pellicle extract including the monomers ellagic acids, gallic acids and methyl gallate. The in viro data on polyphenolic-rich walnut extract demonstrate potent antioxidant capacity with plasma and bad cholesterol (LDL) lipids. This contributes to the understanding of the dietary-derived polyphenolics participation in the complex antioxidant network (Anderson, 2001).

Other contribution of walnuts to one’s health is the prevention or control in the risk of having diseases aside from mentioned previously. The prevention and control of high blood pressure can be attributed to the consumption of walnuts. The International Study on Macro and Micro Nutrients and Blood Pressure conducted a study proving that polyunsaturated fatty acids and omega 3 present in walnuts decreases or stabilizes the blood pressure compare to those who do not eat it. Hirutsugu Ueshima, lead author, said:

With blood pressure, every millimeter counts. The effect of each nutrient is apprently small but independent, so together they can add up to a substantial impact on blood  pressure. If you can reduce blood pressure a few millimeters from eating less salt,           losing few pounds, avoid heavy drinking, eating more vegetables, whole grains and  fruits (for their fiber, minerals, vegetable protein and other nutrients) and getting more   omega 3 fatty acids, then you’ve made a big difference. (Walnuts, 2007).

Walnuts also improved cholesterol profile to those individuals with type 2 diabetes. This can be attributed to the presence of monounsaturated fats, omega 3 fatty acids, alpha-linolinec acids, 16 antioxidants phenols, vitamin E, ellagic and gallic acids.

Walnuts lowers risk of weight gain. According to a study conducted in Spain, consumption of walnuts reduces the risk of gaining weight by 31% than not eating walnut at all (Walnuts, 2007). Incorporating walnuts in the diet is less likely to gain weight than weight gain during withdrawing of walnuts in the diet (Sabate, et al, 2005).  Walnuts are energy-giving food but it does not contributes to weight gain. According to research in Harvard, healthy fat, fibers and proteins in walnuts are affective satiety during dieting (Walnuts and Weight, 2007). A possible explaination for this is because polyunsaturated fatty acids causes less weight gain than saturated fatty acids, instead, plasma linoeic acid and linolinec acid both increases.

The eicosapentaenoic acid, on the other hand, did not increase as well, therefore, the triacylglycerol concentration does not have any modifications. During experimentation, the lack of modifications or alteration of the triacylglycerol concentration may be attributed to several factors like; respondents may have combined hyperlipidemia, may be due to old age or that consumption may contain more polyunsaturated fats than monounsaturated fats (Almario, 2001).

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