Nut Priorities

[Guest guest]

Hi All,

The pdf-available paper posted that follows this preamble

describes other nut goodies that might require consideration in the

relative value of our nuts for our best nutrition.

The Tables 1-5 came up all scrambled and are doctored roughly.

For background definition, there is:

vitamin E: Functions as an antioxidant, binds oxygen free radicals

that can cause tissue damage, may also play a protective role in the

coronary arteries from the damaging effects of cholesterol.

vitamin e deficiency: A nutritional condition produced by a

deficiency of vitamin e in the diet, characterised by posterior

column and spinocerebellar tract abnormalities, areflexia,

ophthalmoplegia, and disturbances of gait, proprioception, and

vibration. In premature infants vitamin e deficiency is associated

with haemolytic anaemia, thrombocytosis, oedema, intraventricular

haemorrhage, and increasing risk of retrolental fibroplasia and

bronchopulmonary dysplasia. An apparent inborn error of vitamin e

metabolism, named familial isolated vitamin e deficiency, has

recently been identified. (cecil textbook of medicine, 19th ed, p1181)

sitosterols: A family of sterols commonly found in plants and

plant oils. Alpha-, beta-, and gamma-isomers have been characterised.

sterol: Any steroid-based alcohol having a hydrocarbon

(aliphatic) side-chain of 8-10 carbons at the 17-beta position and a

hydroxyl group at the 3-beta position (therfore an alcohol).

stigmasterol is an unsaturated plant sterol occurring in plant

fats like such as calabar bean, soybean oil, rape seed and cocoa

butter. ...

Maguire LS, O'Sullivan SM, Galvin K, O'Connor TP, O'Brien NM.

Fatty acid profile, tocopherol, squalene and phytosterol content of

walnuts,

almonds, peanuts, hazelnuts and the macadamia nut.

Int J Food Sci Nutr. 2004 May;55(3):171-8.

PMID: 15223592 [PubMed - indexed for MEDLINE]

Nuts are high in fat but have a fatty acid profile that may be

beneficial in relation to risk of coronary heart disease. Nuts also

contain other potentially cardioprotective constituents including

phytosterols, tocopherols and squalene. In the present study, the

total oil content, peroxide value, composition of fatty acids,

tocopherols, phytosterols and squalene content were determined in the

oil extracted from freshly ground walnuts, almonds, peanuts,

hazelnuts and the macadamia nut. The total oil content of the nuts

ranged from 37.9 to 59.2%, while the peroxide values ranged from 0.19

to 0.43 meq O2/kg oil. The main monounsaturated fatty acid was oleic

acid (C18:1) with substantial levels of palmitoleic acid (C16:1)

present in the macadamia nut. The main polyunsaturated fatty acids

present were linoleic acid (C18:2) and linolenic acid (C18:3). alpha-

Tocopherol was the most prevalent tocopherol except in walnuts. The

levels of squalene detected ranged from 9.4 to 186.4 microg/g. beta-

Sitosterol was the most abundant sterol, ranging in concentration

from 991.2 to 2071.7 microg/g oil. Campesterol and stigmasterol were

also present in significant concentrations. Our data indicate that

all five nuts are a good source of monounsaturated fatty acid,

tocopherols, squalene and phytosterols.

Introduction

There is increasing evidence that diets that

include nuts may be beneficial in decreasing

the risk of coronary heart disease (CHD).

Nuts are high in fat; however, as greater than

75% of the fat present is unsaturated fat, nuts

are thought to have a fatty acid profile that

is cardioprotective. Monounsaturated fatty

acids (MUFA) are the predominant fatty

acids and contribute, on average, approxi-mately

62% of the energy in nuts from fat

(Kris-Etherton et al ., 1999a).

It is widely recognized that the type of

fat in the diet influences plasma cholesterol

levels to a greater extent than total fat intake.

Therefore, replacing saturated fat with un-saturated

fat may be more effective in

lowering the risk of CHD than reducing the

total fat intake (O'Byrne et al ., 1997; Kris-Etherton

et al ., 1999b). Kris-Etherton et al .

(1999b) reported that diets high in MUFA

have a favourable effect on the ratio of total

cholesterol:high-density lipoprotein (HDL)

cholesterol, which is a more accurate indica-tor

of risk for CHD than total cholesterol

level alone. Diets high in MUFA reduce

levels of low-density lipoproteins (LDLs)

without adversely affecting the HDL frac-tion,

thereby reducing risk of CHD.

Epidemiological evidence indicates that

frequent nut consumption lowers the risk of

CHD (Hu et al ., 1998; Rajaram et al ., 2001;

Albert et al ., 2002). However, there is emer-ging

evidence that the decreased risk is not

solely related to the fatty acid profile, but

may be due to the presence of other bioactive

trace components present in nuts. Kris-Etherton

et al . (2001) summarized the find-ings

from 11 clinical studies regarding the

total and lipoprotein-cholesterol response

following incorporation of nuts into various

diets. Using predictive equations, the actual

change in CHD risk was compared with the

estimated response based on fatty acid pro-files

(Kris-Etherton et al ., 2001). Results

indicate the actual change in CHD risk was

greater than the estimated response based on

fatty acid profiles in most instances across all

levels of nut consumption. These results,

therefore, suggest that other bioactive com-ponents,

in addition to fatty acids, are

present in nuts that further reduce CHD

risk. Current food databases contain little

compositional data for nuts, particularly with

respect to potentially bioactive compounds

including phytosterols, squalene and toco-pherols

(Holland et al ., 1992).

Phytosterols are found in plant foods and

are structurally and functionally analogous

to cholesterol in vertebrate animals. b -Sitos-terol,

campesterol and stigmasterol are the

most commonly occurring phytosterols and

constitute 95% of total phytosterols in the

diet. In addition to nuts, phytosterols are

found in a range of seeds, legumes, vegetables

and unrefined vegetable oils (Weihrauch &

Gardner, 1978). The effects of dietary sup-plementation

with phytosterols on serum

cholesterol levels in humans have been re-viewed

comprehensively by several authors

(Gylling & Miettinen, 2000; Law, 2000;

Moreau et al ., 2002; Neil & Huxley, 2002).

In general, phytosterol supplementation

tends to decrease serum levels of total and

LDL cholesterol, and has little effect on

serum levels of HDL cholesterol and trigly-cerides.

Squalene is a 30-carbon, straight-chain

hydrocarbon steroid precursor that is pro-duced

by both animal and plant cells. Squa-lene

is converted to phytosterols in plant cells

(Goodwin, 1996). A number of reports

suggest squalene possesses antioxidant func-tions.

It has been demonstrated to be an

effective quencher of singlet oxygen and

prevents lipid peroxidation in model systems

(Kohno et al ., 1995). Fan et al. (1996)

reported that squalene inhibited sodium

arsenite-induced sister chromatid exchanges

in Chinese ovary-K1 cells and suggested that

the inhibitory effects may be due to its

antioxidant activity. More recently, O'Sulli-van

et al. (2002) demonstrated that squalene

was very effective in protecting against H2 O2 -induced

SCE in Chinese hamster V79 cells.

Tocopherols are powerful antioxidants and

in high doses have been shown to lower the

risk of CHD (Rimm & Stampfer, 1997). This

cardioprotective effect is thought to be due to

inhibition of LDL cholesterol oxidation, a

key step in the atherogenic process.

The aim of the present study was to

determine and compare the total oil content,

fatty acid composition, peroxide value (a

measure of oxidative stability), tocopherol,

phytosterol and squalene content of walnuts,

almonds, peanuts, hazelnuts and the maca-damia

nut.

...

Results

The total oil content of the five selected nuts

ranged from 37.9 to 59.2%, with the maca-damia

nut yielding the greatest percentage of

oil, and the peanut the least (Table 1). The

peroxide values ranged from 0.19 to 0.43 meq

O2/kg oil (Table 1).

The fatty acid profile of the five nuts

determined by capillary-column GC is pre-sented

in Table 2 and a summary of the

important fatty acid parameters is presented

in Table 3. The major MUFA present in all

five nuts was oleic acid (C18:1), with sub-stantial

levels of palmitoleic acid (C16:1)

present in the macadamia nut (Table 2).

The major polyunsaturated fatty acid

(PUFA) present was linoleic acid (C18:2),

with lesser amounts of linolenic acid (C18:3).

Walnut had a particularly high content of

linolenic acid (11.6% of total) compared with

the other nuts (Table 2). The main saturated

fatty acids (STA) present in all samples were

palmitic acid (C16) and stearic acid (C18)

(Table 2). The levels of total UFA in all five

nuts were similar, ranging from 84.5 to

91.6%. However, there were larger variations

between the PUFA and MUFA contents

(Table 3). The mean MUFA and PUFA

contents of the macadamia nut oil were

82.4 g/100 g and 2.4 g/100 g, respectively.

This is in contrast to walnut oil, which

contained 21.2 g/100 g MUFA and 69.0 g/

100 g PUFA. Peanut contained the lowest

levels of MUFA at 38.6 g/100 g (Table 3).

The tocopherol and squalene contents of

the five nuts were also measured (Table 4).

The levels of total tocopherols ranged from

122.3 to 452 microg/g and the order of decreasing

total tocopherol content was almond>

hazenut?walnut>peanut>macadamia nut.

a -Tocopherol was the most prevalent toco-pherol

for all nuts except walnut, ranging

from 21 to 440 microg/g, and was present in much

higher concentrations in almonds and hazel-nuts

than peanuts and the macadamia nut.

The level of a -tocopherol detected in walnuts

was particularly low at 20.6 microg/g. g -Toco-pherol

was measured in concentrations ran-ging

from trace amounts in the macadamia

nut to 300.5 microg/g in walnuts, while d -toco-pherol

was present in trace amounts in all nut

samples (data not shown). Squalene was

detected in all five nuts, with levels ranging

from 9.4 to 186.4 microg/g (Table 4).

The levels of total phytosterols ranged

from 1096 to 2178.4 microg/g oil and the order

of decreasing total phytosterol content

was almond>peanut>macadamia nut>

walnut>hazelnut. b -Sitosterol was the most

abundant sterol, ranging from 991.2 to

2071.7 microg/g, and was present in much higher

concentrations than campesterol and stig-masterol

in all five nuts. Campesterol and

stigmasterol were present at similar concen-trations

(Table 5). The concentrations of

campesterol and stigmasterol were higher in

peanuts, at 198.3 and 163.3 microg/g, respectively,

than in the remaining four nuts, the concen-trations

of which ranged from 51.0 to 73.3

microg/g (campesterol) and 38.1 to 55.5 microg/g

(stigmasterol).

Table 1. Total oil content and peroxide value of oil extracted

from five edible nuts

------------------------------------------------

Oil sample Total oil (g/100 g) Peroxide value (meq O2/kg oil)

--------------------------------------

Hazelnut 49.2+/-0.04

Macadamia 59.2+/-0.03

Peanut 37.9+/-0.04

Walnut 50.8+/-0.07

Almond 40.8+/-0.004

-------------------------------------

Results are the mean +/- standard error of three

independent experiments.

Table 2. Fatty acid composition (% of total) of

oil extracted from five edible nuts

--------------------------------------------------------------

Fatty acid

Oil sample 14:0 16:0 16:1 18:0 18:1 18:2 18:3 20:0 20:3 20:5 22:0 22:6

Hazelnut 0.13 5.82 0.29 2.74 79.30 10.39 0.46 0.16 ND ND ND ND

Macadamia 0.95 8.37 17.28 3.17 65.15 2.31 0.06 2.28 0.01 ND 0.2 0.27

Peanut 0.03 11.08 0.15 2.66 38.41 44.6 0.58 1.57 0.02 0.02 0.1 0.75

Walnut 0.13 6.70 0.23 2.27 21.00 57.46 11.58 0.08 ND 0.06 0.07 ND

Almond 0.06 6.85 0.63 1.29 69.24 21.52 0.16 0.16 ND ND 0.05 ND

-----------------------------------------------------------------

Reults are the mean value from three independent experiments.

ND, not determined.

Table 3. Summary of the important fatty acid

parameters of oil extracted from five edible nuts

-------------------------------------------------------------------

Oil sample PUFA MUFA SFA USFA USFA/SFA

------------------------------------------------------------

Hazelnut 10.9 79.6 9.2 90.4 9.9

Macadamia 2.4 82.4 15.1 84.8 5.6

Peanut 46.0 38.6 15.5 84.5 5.45

Walnut 69.0 21.2 9.5 90.3 9.5

Almond 21.7 69.9 8.5 91.6 10.8

-----------------------------------------------------------------

Results are the mean value (g/100 g)

from three independent experiments.

Table 4. Squalene and tocopherol content of

oil extracted from five edible nuts (microg/g oil)

extracted from five edible nuts

---------------------------------------------------------

Oil Squalene a-Tocopherol g-Tocopherol

---------------------------------------------------------------------

Hazelnut 186 310 61.2

Macadamia 185.0+/-24.5 310 61

Peanut 98.3+/-6.7 60.3+/-1.8 20.6+/-31.0

Almond 95.0+/-4.8 439 12.5

Walnut 9.4 20.6 300

Almond 95.0 440 51.2

---------------------------------------------------------------

Results are the mean value +/-standard error of

the mean from three independent experiments.

Table 5. Campesterol, stigmasterol and b -sitosterol content

of oil extracted from five edible nuts (microg/g oil)

------------------------------------------------------

Hazelnut 67 38 991

Peanut 198 163 1363

Macadamia 73.3+/-2.7 1506.7+/-21.4 163.3+/-103.9

Walnut 51.0+/-11.0 1129.5+/-10.8 51.7+/-25.9

Almond 55 52 2072

----------------------------------------------------

Results are the mean value +/-standard error of

the mean from three independent experiments.

Discussion

Kris-Etherton et al. (2001) reviewed epide-miological

and clinical studies that have

demonstrated the effects of nuts on cardio-vascular

health and concluded that, overall,

the results suggest an independent beneficial

effect of nut consumption on CHD risk. The

exact mechanism by which nuts exert this

protective effect is not clear. In addition to

their highly unsaturated fatty acid profile,

nuts contain other constituents that could

also offer protection. These constituents

include antioxidants (e.g. tocopherols), squa-lene

and plant sterols.

In agreement with previously published

studies, our data indicate that the fat content

of all five nut types was high, between 37 and

59%. Analysis of the fatty acid profile of the

nuts indicates a high unsaturated/saturated

ratio. The main contributing saturated fatty

acids for all nuts included stearic acid (C18:0)

and palmitic acid (C16:0) with traces of

myristic acid (C14:0) and eicosanoic acid

(C20:0). The highest levels of saturated fatty

acid were found in the macadamia nut and

peanuts. Although classified with other nuts,

peanuts are legumes and grow underground,

often being referred to as groundnuts. Re-sults

from this study confirm that, composi-tionally,

they are similar to the tree nuts.

Higgs (2002) has reviewed the protective role

that peanuts may have against certain dis-eases,

including CHD. The main unsaturated

fatty acids in the nuts studied included oleic

acid (C18:1), linoleic acid (C18:2), linolenic

acid (C18:3) and palmitoleic acid (C16:1).

Unlike hazelnuts and almond, where the

majority of the MUFA was oleic acid

(C18:1), in the macadamia nut 21% was

palmitoleic acid (C16:1). The macadamia

oil determined in this study contained the

highest level of MUFA, higher than MUFA

levels reported in olive oil, high-oleate saf-flower

oil and rapeseed oil (Leissner et al .,

1989). Peanuts had higher levels of linoleic

acid (C18:2) and a low level of oleic acid

(C18:1) in comparison with previously pub-lished

data (Hinds, 1995). Walnuts were a

significant source of omega-3 fatty acids.

Linolenic acid (C18:3) represented approxi-mately

12% of their total fatty acid composi-tion.

One potential mechanism proposed by

which nuts offer protection against CHD

includes a reduction in fatal ventricular

arrhythmias (Albert et al ., 2002). There

are several components of nuts that could

potentially exert such a role, including the

a -linolenic content. Walnuts, therefore, could

be particularly significant in this regard.

The levels of tocopherols and squalene

differed between nut varieties. a -Tocopherol

was the main tocopherol isomer present in all

nuts analysed with the exception of walnut.

The a -tocopherol content ranged between

20.6 microg/g oil in walnuts and 439.5 microg/g oil in

almonds. In general, tocopherol levels were

in accordance with previous publications

(Savage et al ., 1997, 1999; Parcerisa et al .,

1998). However, macadamia nuts had a much

higher content of a -tocopherol (122.3 microg/g

lipid) than was previously reported by Kaij-ser

et al . (2000), who reported levels of

0.8 - 1.1 microg/g lipids. The macadamia nuts

examined in the study by Kaijser et al .

(2000) were harvested from the North Island

of New Zealand. Unfortunately, the source

of the macadamia nuts used in the present

study is unknown. It has been reported that

the fatty acid profile and phytochemical

content of nuts (e.g. walnuts) varies between

cultivars (Greve et al ., 1992). Therefore, it

is possible that differences between the

a -tocopherol content of our macadamia

nuts and those of Kaijser et al . (2000) could

be explained by cultivar variations. Clearly,

this remains to be confirmed by analysing

different cultivars of the macadamia nut

for a -tocopherol content. The g -tocopherol

content of the nuts was also analysed in

this study, and ranged from trace levels in

macadamia nuts to 300.5 microg/g in walnuts.

Walnuts were the only nuts that contained

g -tocopherol in higher concentrations than

a -tocopherol. Similar findings were reported

by Savage et al . (1999) and Lavedrine et al .

(1997). Some reports suggest g -tocopherol

has a higher antioxidant capacity in model

systems than a -tocopherol (Wolf, 1997; Sald-een

et al., 1999).

There is a paucity of information regarding

the content of squalene in nuts. However,

some literature does exist on the content of

squalene in vegetable oils. Owen et al . (2000)

reported a mean squalene content of 2900

microg/g in olive oils, with seed oils having a value

of 240 microg/g. Soybean oil has been reported to

contain levels of squalene of 220 microg/g oil

(Mendes et al ., 2002). In this study the level

of squalene in the nuts varied between nut

types, ranging from 9.4 microg/g oil in walnuts to

186.4 microg/g oil in hazelnuts. The level found in

hazelnuts is comparable with soybean oil.

There has been growing interest in squalene

as a potential chemopreventative agent

(, 2000). The average intake of squalene

in the United States is 30 mg/day. However,

when olive oil consumption is high the intake

of squalene can reach 200 - 400 mg/day, as

observed in the Mediterranean countries

(Gerber, 1994). Experimental studies have

shown that squalene can inhibit chemically-induced

colon, lung and skin tumorigenesis

in rodents (reviewed by , 2000). There-fore,

it has been proposed that the decreased

risk for various cancers associated with high

olive oil consumption may, in part, be due to

the presence of squalene. In addition, squa-lene

has been shown to behave as an

antioxidant in certain model systems as

outlined in the Introduction. Uncontrolled

production of reactive oxygen species con-tributes

to the pathogenesis of cardiovascular

disease and cancer. We demonstrate, in the

present study, that nuts can also be a

significant source of dietary squalene.

For all five nuts analysed, b -sitosterol was

the most predominant sterol present ranging

between 991 and 2071 microg/g. Little difference

between contents of campesterol and stig-

masterol was evident. Weihrauch & Gardner

(1978) reported that walnuts had a campes-terol

content of 60 microg/g, but only contained

trace levels of stigmasterol. In this study

walnuts had a campesterol content of

51 microg/g but the stigmasterol levels measured

55 microg/g. Levels of stigmasterol present in

hazelnuts and macadamia nuts are in line

with previously reports (Savage et al ., 1997;

Parcerisa et al ., 1998, 2000; Kaijser et al .,

2000). In comparison with the other nuts

analysed, peanuts had a significantly higher

campesterol and stigmasterol content.

Peroxide values have been used to assess

rancidity in nuts (Fourie & Basson, 1989). In

this study the peroxide value ranged between

0.19 meq O2 /kg oil for almond and 0.43 meq

O2 /kg for hazelnuts. These levels indicate that

the nuts were of good quality from the

perspective of oxidative stability. Savage

et al . (1999) observed a positive relationship

between the peroxide value and total toco-pherol

content. On analysis of our results,

almond had the lowest peroxide value and

had the highest content of tocopherols;

however, this trend is not seen with the other

nuts types. No correlation was observed

between the peroxide value and the toco-pherol

content, phytosterol content, linoleic

acid levels, linolenic acid levels or the ratio of

unsaturated/saturated fatty acid ratio.

In conclusion, this study illustrates some

differences in total oil, fatty acid composi-tion,

tocopherol, squalene and phytosterol

contents between different nut types. In

general, however, all nuts studied had a

favourable unsaturated/saturated fatty acid

ratio. Squalene levels were high in all samples

with the exception of walnut. However, wal-nuts

contained considerably higher levels of

g -tocopherol. Phytosterol levels did not vary

significantly between the different nuts.

Therefore, while certain compositional dif-ferences

exist between individual types of

nut, all have a beneficial fat and phytochem-ical

profile from a CHD perspective.

Cheers, Al Pater

[Guest guest]

Although they include peanuts, as most of us know, peanuts are in the

" legume " family, not the " nut " family. Although perhaps the effect on the

body is more like a nut.........

Hmmm, being that peanuts are a legume, I wonder if they lower cholesterol

like beans and the like?

on 2/6/2005 4:37 PM, old542000 at apater@... wrote:

> Maguire LS, O'Sullivan SM, Galvin K, O'Connor TP, O'Brien NM.

> Fatty acid profile, tocopherol, squalene and phytosterol content of

> walnuts,

> almonds, peanuts, hazelnuts and the macadamia nut.

> Int J Food Sci Nutr. 2004 May;55(3):171-8.

> PMID: 15223592 [PubMed - indexed for MEDLINE]