Skip to content

Advertisement

  • Research
  • Open Access

Green leafy vegetables in diets with a 25:1 omega-6/omega-3 fatty acid ratio modify the erythrocyte fatty acid profile of spontaneously hypertensive rats

  • 1Email author,
  • 1 and
  • 2
Lipids in Health and Disease201817:140

https://doi.org/10.1186/s12944-018-0723-7

Received: 12 July 2017

Accepted: 25 March 2018

Published: 15 June 2018

Abstract

Background

In addition to the actual composition of the diet (i.e. nutrient composition, food groups), the omega-6/omega-3 fatty acid ratio has been demonstrated to influence the tissue fatty acid profile and subsequently the risk for cardiovascular and other diseases. Likewise, the consumption of green leafy vegetables (GLVs) may favorably reduce the risks associated with disease. Although an ~ 3:1 omega-6/omega-3 fatty acid ratio (ω-6/ω-3 FAR) is recommended, the typical American diet has an ~ 25:1 ω-6/ω-3 FAR. Previous research affirms the ability of collard greens (CG), purslane (PL), and sweet potato greens (SPG) to improve the hepatic profile of spontaneously hypertensive rats (SHRs). The aim of the present study was to determine the influence of GLVs, incorporated (4%) into diets with a 25:1 ω-6/ω-3 FAR, on the erythrocyte fatty acid profile of male SHRs.

Methods

SHRs (N = 50) were randomly assigned to one of five dietary groups – standardized control (AIN-76A), Control (25:1 ω-6/ω-3 FAR), CG (25:1 ω-6/ω-3 FAR + 4% CG), PL (25:1 ω-6/ω-3 FAR + 4% PL) or SPG (25:1 ω-6/ω-3 FAR + 4% SPG). Following 6 weeks consumption of diets, SHRs erythrocyte fatty acid profiles were determined by gas-liquid chromatography.

Results

Significantly lower percentages of total saturated fatty acids (p < 0.05) and greater percentages of polyunsaturated fatty acids were present among SHR erythrocytes following the consumption of diets containing CG, PL and SPG. Total polyunsaturated fatty acids were greatest among SHRs consuming diets containing purslane.

Conclusions

The present study demonstrates the ability of GLVs to mitigate the potential effects of an elevated ω-6/ω-3 FAR, which may contribute to an atherogenic fatty acid profile, inflammation and disease pathogenesis. Dietary recommendations for disease prevention should consider the inclusion of these GLVs, particularly among those consuming diets with an ω-6/ω-3 FAR that may promote disease.

Keywords

  • Erythrocyte
  • Collard greens
  • Fatty acid profile
  • Omega-6/omega-3 fatty acid ratio
  • Purslane
  • Spontaneously hypertensive rat
  • Sweet potato greens

Background

Epidemiological and clinical evidence affirms that the consumption of diets with elevated omega-6/omega-3 fatty acid ratios (ω-6/ω-3 FARs) to be associated with an increased risk for hypertension, cardiovascular disease (CVD), diabetes and other chronic diseases [13]. Further, the dietary ω-6/ω-3 FAR has been demonstrated to influence tissue fatty acid compositions [4, 5]. Although an ~ 3:1 ω-6/ω-3 FAR is recommended, the typical American (i.e. Western) diet has an ~ 25:1 ω-6/ω-3 FAR [6, 7]. The excessive consumption of vegetable oils, processed foods and refined products, such as those observed in Western cultures, are believed to contribute to elevations in the dietary ω-6/ω-3 FAR [8, 9]. Conversely, plant-based diets, particularly those containing vegetables abundant in α-linolenic acid, have lower ω-6/ω-3 FARs [10] and are plentiful in antioxidant and bioactive compounds that have been associated with decrease risk for chronic disease [1113].

Green, leafy vegetables (GLVs), rich of sources of antioxidants and bioactive compounds, have been demonstrated to improve antioxidant status and reduce the risks associated with disease [14]. Further, dietary patterns that promote the increased consumption of GLVs, such as the Mediterranean diet, may be beneficial in reducing the risks associated with disease pathogenesis [1518]. In addition, the Dietary Approaches to Stop Hypertension (DASH) diet endorses the consumption of plants commonly found in the African American diet such as collard greens and sweet potatoes, for the reduction of the risks associated with hypertension and other chronic diseases [1922].

Collard greens (Brassica oleracea), a traditional GLV with the diet of Americans living in the southern United States, in addition to purslane (Portulaca oleracea) and sweet potato greens (Ipomoea batatas L.), novel GLVs within the diet, are potent dietary reservoirs of antioxidant and bioactive compounds that may decrease disease risk [23, 24]. Previous research has demonstrated the ability of collard greens, purslane and sweet potato greens to favorable modify the hepatic fatty acid profile of spontaneously hypertensive rats after 4 weeks consumption [25]. The aim of the present research study was to evaluate the influence of collard greens (CG), purslane (PL) and sweet potato greens (SPG), supplemented into diets with a 25:1 ω-6/ω-3 FAR, on the erythrocyte fatty acid profiles of male spontaneously hypertensive rats.

Methods

Animals and diets

Fifty (N = 50) male spontaneously hypertensive rats (SHRs), 4 weeks of age, were housed individually in clear polypropylene cages (43x27x15cm), with temperature and relative humidity controlled at 70-72 °C and 50–55%, respectively. SHRs were maintained on a 12:12 h light-dark photoperiod cycle. Following a 10 day acclimation period, SHRs were randomly assigned to one of four experimental dietary groups with a 25:1 ω-6/ω-3 FAR: 1) Control, 2) 4% CG, 3) 4% PL, 4) 4% SPG; 10 SHRs were assigned to the standardized control dietary group and received the AIN-76A diet for the duration of the research study. SHRs consumed the diets for 6 weeks. The compositions of the experimental diets are presented in Table 1. Animals were paid fed based on the average previous day’s intake of SHRs consuming the experimental diets containing CG, PL and SPG. SHRs were allowed to consume water ad libitum.
Table 1

Ingredient composition of standardized control and experimental diets fed to SHRs for 6 weeksa

 

Dietary Group

Ingredient (%)

AIN-76A

C

CG

PL

SPG

Sucrose

50.00

41.96

39.27

39.49

39.39

Casein (Vitamin Free)

20.00

18.00

16.82

16.53

16.68

Corn Starch

15.00

15.00

15.00

15.00

15.00

Powdered Cellulose

5.00

5.00

5.00

5.00

5.00

AIN-76 Mineral Mix

3.50

3.50

3.50

3.50

3.50

AIN-76 Vitamin Mix

1.00

1.00

1.00

1.00

1.00

DL-Methionine

0.30

0.30

0.30

0.30

0.30

Choline Bitartrate

0.20

0.20

0.20

0.20

0.20

Ethoxyquinb

0.00

0.00

0.00

0.00

0.00

Corn Oil

5.00

12.06

11.96

12.01

11.97

Soybean oil

2.91

2.88

2.89

2.89

Fish Oil

Cholesterol

0.07

0.07

0.07

0.07

Collard Greens

4.00

Purslane

4.00

Sweet potato Greens

4.00

aDiets formulated and manufactured by the Division of Land O’Lakes Purina Feed, LLC, Richmond, IN. C, control; CG collard greens, PL purslane; SPG sweet potato greens; bEthoxyquin content = 0.0010%

AIN-76A = AIN -76, standard rodent chow; C (control diet) = AIN-76A diet with a 25:1 ω-6/ω-3 FAR; CG = AIN-76A diet with a 25:1 ω-6/ω-3 FAR + 4% collard green powder; PL = AIN-76A diet with a 25:1 ω-6/ω-3 FAR + 4% purslane powder; SPG = AIN-76A diet with a 25:1 ω-6/ω-3 FAR + 4% sweet potato green powder

Following a 24 h fast animals were anesthetized using a Ketamine-Acepromazine combination cocktail and then euthanatized via over-inhalation of carbon dioxide. Blood was collected via cardiac puncture, collected in heparin-coated tubes and centrifuged at 2500 rpm at 10 °C for 30 min to separate plasma and erythrocytes. Following centrifugation, samples were stored at − 80 °C prior to analyses. Eight (n = 8) SHRs were randomly selected from each dietary group for the erythrocyte fatty acid profile analysis. The procedures involved in the care and use of the animals were approved by the Tuskegee University Animal Care and Use Committee.

Erythrocyte fatty acid extraction

Erythrocyte fatty acid methyl esters (FAMEs) were prepared following transesterification with boron trifluoride (BF3, cat# 3–3021, 12% methanol, Supelco, Inc., Bellefonte, PA) using the procedures previously described by Masood et al. [26]. To approximately 0.01 g of SHR erythrocytes, 100 μl of nonadecanoic acid (C19:0, Nu-Chek Prep, Inc., Elysian, MN), dissolved in hexane (1.0 ml), and BF3 (1.0 ml) was added. Fatty acid methyl esters (FAMEs) were prepared by heating the mixture in a hot water bath at 55 °C for 90 min and subsequently placed in an ice bath for 5 min. Hexane (2.0 ml) and deionized water (1.0 ml) were added, Pyrex glass culture tubes were flushed with nitrogen and vortexed for 15 s. Following centrifugation at 2000 rpm for 5 min, the top organic layer, containing the FAMEs were collected and placed in gas chromatography (GC) vials for GC analysis. Samples were analyzed in duplicate.

GC analysis of FAMEs

Erythrocyte FAMEs were isolated and quantified using a HP 6890 N network gas chromatograph system (Agilent Technologies, Santa Clara, CA) equipped with a HP 7683 series automated injector, flame ionization detector and a DB23 fused silica capillary high resolution gas chromatograph column (60 m, 0.25 mm, i.d., 0.25 μm film thickness, J&W Scientific, Folsom, CA). Data are expressed as percentages of total fatty acid.

Statistical analysis

Statistical analyses were conducted using analysis of variance software (SAS Software, Cary, NC). Duncan’s post hoc procedures were performed to test if differences existed among SHRs consuming the different diets. Statistical significance was determined at p < 0.05.

Results

Erythrocyte saturated fatty acid (SFA) concentrations (% total fatty acids) of SHRs consuming diets with a 25:1 ω-6/ω-3 FAR are presented in Table 2. Erythrocyte SFA concentrations were less among SHRs consuming diets containing CG (41.72 ± 2.71), PL (39.65 ± 1.41) and SPG (38.63 ± 0.80) in comparison to the standardized control (71.82 ± 3.43) and control (45.25 ± 2.36) diets. Palmitic acid was the most abundant erythrocyte SFA among SHRs, with SHRs consuming diets containing CG (24.71± 1.60), PL (23.77± 0.90) and SPG (23.05 ± 0.46) - demonstrating lower percentages of this fatty acid in comparison to the standardized control (60.05 ± 5.47; p < 0.05) and control (27.08± 1.61) diets.
Table 2

SHR erythrocyte saturated fatty acid composition (%total fatty acids) following the consumption of diets with a 25:1 ω-6/ω-3 FAR for 6 weeks§

  

Dietary Group

Fatty acid

Structure

AIN-76A

C

CG

PL

SPG

Capric

C10:0

nd

nd

nd

nd

nd

Undecanoic

C11:0

nd

nd

nd

nd

nd

Lauric

C12:0

0.24 ± 0.00a

0.43 ± 0.22ab

0.06 ± 0.01a

0.12 ± 0.04ab

0.16 ± 0.06b

Tridecyclic

C13:0

nd

nd

nd

nd

nd

Myristic

C14:0

0.17 ± 0.02a

0.23 ± 0.05ab

0.15 ± 0.03a

0.20 ± 0.03ab

0.29 ± 0.04b

Pentadecanoic

C15:0

0.12 ± 0.01a

0.14 ± 0.01ab

0.13 ± 0.01ab

0.17 ± 0.02ab

0.18 ± 0.01b

Palmitic

C16:0

60.08 ± 5.47a

27.08 ± 1.61b

24.71 ± 1.60b

23.77 ± 0.90b

23.05 ± 0.46b

Heptadecanoic

C17:0

nd

nd

nd

nd

nd

Stearic

C18:0

11.15 ± 2.80a

16.80 ± 1.04b

16.33 ± 1.05b

15.01 ± 0.52ab

14.52 ± 0.29ab

Arachidic

C20:0

nd

0.20 ± 0.01

nd

nd

nd

Behenic

C22:0

nd

nd

nd

nd

nd

Lignoceric

C24:0

nd

nd

nd

nd

nd

Total SFAs

 

71.82 ± 3.43 a

45.25 ± 2.36 b

41.72 ± 2.71 b

39.65 ± 1.41 b

38.63 ± 0.80 b

§Data are (expressed as) mean percentage ± SE. Values in the same row that do not share the same superscript letter are significantly different according to analysis of variance and Duncan’s post hoc procedures (p < .05); nd not detected

Total monounsaturated fatty acids (MUFAs) among SHRs consuming diets containing GLVs ranged from 13.11 ± 0.35 (CG) to 14.98 ± 0.70 (SPG) and were slightly less than consuming the control diet (15.10 ± 0.25) (Table 3). Oleic acid, the most abundant MUFA present, was greatest among SHRs assigned to the control (9.41 ± 0.33), CG (8.56 ± 0.35) and PL (8.55 ± 0.25) dietary groups. Significantly greater amounts of nervonic acid were present following the consumption of diets containing the GLVs in comparison to the standardized control diet; a slightly greater percentage of nervonic acid was present in the erythrocytes of SHRs consuming the control diet.
Table 3

SHR erythrocyte monounsaturated fatty acid composition (%total fatty acids) following the consumption of diets with a 25:1 ω-6/ω-3 FAR for 6 weeks§

  

Dietary Group

Fatty acid

Structure

AIN-76A

C

CG

PL

SPG

Undecenoic

C11:1

nd

nd

nd

nd

nd

Dodecenoic

C12:1

nd

nd

nd

nd

nd

Tridecanoic

C13:1

nd

nd

nd

nd

nd

Myristoleic

C14:1n5

nd

nd

nd

nd

nd

Pentadecenoic

C15:1n5

0.58 ± 0.08a

0.04 ± 0.00b

0.06 ± 0.00b

0.06 ± 0.01b

0.06 ± 0.00b

Palmitoleic

C16:1n7

0.28 ± 0.05a

0.14 ± 0.01b

0.16 ± 0.01b

0.15 ± 0.02b

0.10 ± 0.02b

Palmitelaidic

C16:1n7t

0.43 ± 0.04a

0.41 ± 0.05a

0.35 ± 0.05a

0.37 ± 0.04a

0.56 ± 0.03b

Heptadecenoic

C17:1n7

nd

nd

nd

nd

nd

Elaidic

C18:1n9t

nd

nd

nd

nd

nd

Vaccenic

C18:1n11c

nd

nd

nd

nd

nd

Trans-vaccenic

C18:1n7t

nd

nd

nd

nd

nd

Oleic

C18:1n9c

5.60 ± 0.61a

9.41 ± 0.33c

8.56 ± 0.35bc

8.55 ± 0.25bc

7.76 ± 0.23b

Cis-vaccenic

C18:1n7c

1.30 ± 0.17a

1.88 ± 0.08b

1.71 ± 0.07b

1.78 ± 0.06b

2.31 ± 0.09c

cis-5 Eicosenoic

C20:1n15

nd

0.31 ± 0.04

nd

nd

nd

cis-8-Eicosenoic

C20:1n12

nd

0.26 ± 0.03

nd

nd

nd

Eicosenoic

C20:1n9

0.07 ± 0.00a

0.26 ± 0.03b

0.23 ± 0.04b

0.19 ± 0.03ab

0.22 ± 0.02b

Erucic

C22:1n9

nd

nd

nd

nd

nd

Nervonic

C24:1n9

0.90 ± 0.20a

2.38 ± 0.23b

2.03 ± 0.19b

2.61 ± 0.41b

4.08 ± 0.40c

Total MUFAs

 

9.09 ± 1.01 a

15.10 ± 0.25 c

13.11 ± 0.35 b

13.64 ± 0.39 bc

14.98 ± 0.70 c

§Data are (expressed as) mean percentage ± SE. Values in the same row that do not share the same superscript letter are significantly different according to analysis of variance and Duncan’s post hoc procedures (p < .05); nd not detected

A significantly greater percentage of polyunsaturated fatty acids (PUFAs) were present in the erythrocytes of SHRs assigned to the control (40.30 ± 2.91), CG (45.50 ± 2.95), PL (46.70 ± 1.49) and SPG (46.51 ± 1.04) diets versus the standardized control diet (19.32 ± 2.81) (Table 4). In comparison to the control diet, slightly lower percentages of linoleic acid were present in the erythrocytes of SHRs consuming diets containing CG (8.69 ± 0.12) and PL (9.15 ± 0.19), while a significantly greater percentage of this fatty acid was present following the consumption of the diet containing SPG (10.3 ± 0.37). A greater percentage of α-linolenic acid was found in the erythrocytes of SHRs consuming diets containing CG (0.24 ± 0.07), PL (0.48 ± 0.22) and SPG (0.31± 0.02) in contrast to those consuming the standardized control and control diet.
Table 4

SHR erythrocyte polyunsaturated fatty acid composition (%total fatty acids) following the consumption of diets with a 25:1 ω-6/ω-3 FAR for 6 weeks§

  

Dietary Group

Fatty acid

Structure

AIN-76A

C

CG

PL

SPG

Linoelaidic

C18:2n6t

nd

nd

nd

nd

nd

Linoleic

C18:2n6c

3.68 ± 0.31a

9.26 ± 0.25b

8.69 ± 0.12b

9.15 ± 0.19b

10.31 ± 0.37c

γ-Linolenic

C18:3n6

0.23 ± 0.02a

0.63 ± 0.31a

8.48 ± 1.29b

6.43 ± 2.09b

5.07 ± 1.55b

α-Linolenic

C18:3n3

0.10 ± 0.04a

0.09 ± 0.02a

0.24 ± 0.07a

0.48 ± 0.22a

0.31 ± 0.02a

Eicosadienoic

C20:2n6

0.20 ± 0.03a

nd

0.51 ± 0.02bc

0.56 ± 0.03c

0.44 ± 0.03b

Eicosatrienoic

C20:3n6

0.19 ± 0.05a

0.43 ± 0.01b

0.40 ± 0.03b

0.40 ± 0.02b

0.57 ± 0.03c

Arachidonic

C20:4n6

12.25 ± 2.11a

22.65 ± 2.37b

22.41 ± 1.69b

22.09 ± 1.76b

21.67 ± 0.87b

Eicosatrienoic

C20:3n3

nd

0.16 ± 0.03a

0.17 ± 0.01a

nd

nd

Eicosapentaenoic

C20:5n3

nd

0.29 ± 0.07a

nd

nd

1.41 ± 0.23b

Docosadienoic

C22:2n6

nd

nd

nd

nd

nd

Docosatetraenoic

C22:4n6

1.30 ± 0.24a

2.26 ± 0.60b

2.02 ± 0.17 ab

2.79 ± 0.34b

1.67 ± 0.33ab

Docosatrienoic

C22:3n3

0.78 ± 0.23a

1.12 ± 0.12a

0.84 ± 0.08a

1.07 ± 0.18a

0.71 ± 0.12a

Docosapentaenoic

C22:5n3

nd

nd

nd

nd

nd

Docosahexaenoic

C22:6n3

0.68 ± 0.08a

3.19 ± 0.52bc

1.78 ± 0.15ab

3.86 ± 1.61c

4.48 ± 0.67c

Total PUFAs

 

19.32 ± 2.81 a

40.30 ± 2.91 b

45.50 ± 2.95 b

46.70 ± 1.49 b

46.51 ± 1.04 b

§Data are (expressed as) mean percentage ± SE. Values in the same row that do not share the same superscript letter are significantly different according to analysis of variance and Duncan’s post hoc procedures (p < .05); nd not detected

Discussion

To evaluate the hypothesis that the addition of collard greens (CG), purslane (PL) or sweet potato greens (SPG) into diets with a 25:1 ω-6/ω-3 FAR will favorably modify the erythrocyte fatty acid profile, the present research was undertaken to determine the effects of the consumption of these GLVs on erythrocyte fatty acid profiles of spontaneously hypertensive rats (SHRs). Remarkably, diets supplemented with these GLVs mediated an increase in both erythrocyte mono- and polyunsaturated fatty acids, which may be beneficial in reducing the risk associated with chronic disease.

Previous research has demonstrated the ability of the ω-6/ω-3 FAR (i.e. linoleic acid:α-linolenic acid) to influence plasma docosahexaenoic acid (DHA) concentrations [27]. In a study by Ponder et al., erythrocyte DHA concentration increased by 20% when the linoleic: alpha linolenic acid (LA:ALA) ratio was decreased [28]. In addition to the ω-6/ω-3 FAR, dietary fatty acids are able to influence the erythrocyte fatty acid composition [29], which in turn is believed to be a customary indicator of long-term fatty acid intake [30]. Earlier studies found the induction of marginal changes in erythrocyte fatty acid composition by dietary fat [31]. This relationship becomes even more pronounced as the erythrocyte fatty acid composition may be an indicator of disease risk, with the PUFA content of erythrocytes being inversely associated with metabolic syndrome [32]. Reductions in erythrocyte omega-3 fatty acids have been associated with depression [33], attention deficit disorder [34] and other common mood disorders [35, 36]. Further, it has been suggested that omega-3 fatty acid deficiency may serve as a critical element in understanding the relationship between depression and cardiovascular diseases [37, 38]. Epidemiological evidence has affirmed that there exists an inverse relationship between omega-3 polyunsaturated fatty acid levels and cardiovascular disease [3942]. However, others found omega-3 polyunsaturated fatty acid supplementation to not be associated with reductions in cardiovascular disease risk, morbidities and mortalities [43]. Further, inflammation and autoimmune diseases are believed to be exacerbated when there is insufficient omega-3 polyunsaturated fatty acids to combat the deleterious effects of pro-inflammatory cytokines and agents [44, 45].

Correcting the dietary deficiency of omega-3 fatty acids was found to favorably influence the fatty acid composition of erythrocytes in monkeys by increasing DHA content [46]. Supplementing omega-3 polyunsaturated fatty acids into the diets of pregnant women, resulted in increases in both maternal and neonatal erythrocyte concentrations of eicosapentaenoic acid (EPA) and DHA [47]. Lower levels of erythrocyte omega-3 fatty acids coupled with subsequent higher ω-6/ω-3 FARs significantly increased the risk for preeclampsia among pregnant women [48]. In addition, the source of omega-3 fatty acids was found to alter erythrocyte omega-3 fatty acid composition, with fish oil yielding a more pronounced increase in erythrocyte DHA and total omega-3 fatty acids than flaxseed oil [32].

In addition to a reduction in the ω-6/ω-3 FAR, the egg yolk omega-3 fatty acid content was increased among chickens fed diets supplemented with purslane for 84 days [49]. In another study, the inclusion of purslane and/or flaxseed oil into the diets of laying hens yielded similar results, with the purslane resulting in increased egg yolk omega-3 fatty acids [50]. Modifying the ω-6/ω-3 FAR has also been demonstrated to improve egg quality characteristics (e.g. egg weight, yolk weight, shell weight) in hens, as well as facilitating the production of eggs with higher omega-3 and other polyunsaturated fatty acid contents [51]. In this same study, greater dietary ω-6/ω-3 FARs yielded unfavorable egg characteristics that may have an adverse impact on consumer health. Increased percentages of these fatty acids may act as cellular antioxidants thwarting oxidative and inflammatory pathways implicated in disease pathogenesis [52, 53].

Lower ω-6/ω-3 FARs are desirable in reducing the risks associated with cardiovascular and other diseases [54, 55]; it has been suggested that increasing the dietary intake of omega-3 fatty acids is a viable option for optimizing tissue ω-6/ω-3 FARs [2, 56]. In the current research study a 25:1 ω-6/ω-3 FAR was examined, as this is the ratio found in the typical Western diet (i.e. American). Collard greens, purslane and sweet potato greens, incorporated into the experimental diets of the current study, have demonstrated beneficial cardioprotective, chemopreventive and anti-inflammatory effects in previous studies [5763]. The inclusion of these GLVs resulted in increased mono- and polyunsaturated fatty acid percentages within the SHR erythrocyte, which may in turn decrease the risks associated with disease pathogenesis in an animal model predisposed to developing hypertension and other associated comorbidities.

Conclusions

The findings of this research study provide evidence of the ability of collard greens, purslane and sweet potato greens to modify the erythrocyte fatty acid profile, even in the presence of diets with an elevated omega-6/omega-3 fatty acid ratio. The inclusion of GLVs into diets with greater than recommended omega-6/omega-3 fatty acid ratios may be useful in amending tissue and cellular fatty acid profiles in ways that may be useful in mitigating disease risk. Further, the increased PUFA and omega-3 fatty acid content of SHR erythrocytes consuming diets containing these green leafy vegetables suggest the antioxidant and erythroprotective nature of these vegetables and their potential use as a functional food with therapeutic consequences.

Abbreviations

ω-6/ω-3 FAR: 

omega-6/omega-3 fatty acid ratio

ALA: 

Alpha linolenic acid

CG: 

Collard greens

CVD: 

Cardiovascular disease

DHA: 

Docosahexaenoic acid

EPA: 

Eicosapentaenoic acid

FAMEs: 

Fatty acid methyl esters

GC: 

Gas chromatography

GLVs: 

Green leafy vegetables

LA: 

Linoleic acid

MUFA: 

Monounsaturated fatty acid

PL: 

Purslane

PUFA: 

Polyunsaturated fatty acid

SFA: 

Saturated fatty acid

SHR: 

Spontaneously hypertensive rat

SPG: 

Sweet potato greens

Declarations

Acknowledgements

Dr. Daniel Abugri provided invaluable consultation and technical services during the research study.

Funding

This research was supported by the Tuskegee University College of Agriculture, Environment and Nutrition Sciences and The Alabama Collaboration for Cardiovascular Equality (ACCE).

Availability of data and materials

All data generated or analyzed during this study are included in this published article.

Authors’ contributions

MJ contributed to the conception and design of the study, performed the animal study, erythrocyte fatty acid profile analysis, analyzed data, drafted and edited the manuscript. RDP contributed to the design of the study, supervised the project and edited the manuscript. WHM contributed to the design of the study, assisted in the statistical analysis of the data and edited the manuscript. All authors read and approved the final manuscript.

Ethics approval

The procedures involved in the care and use of the animals were approved by the Tuskegee University Animal Care and Use Committee (Tuskegee, AL, USA).

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Authors’ Affiliations

(1)
Department of Food and Nutritional Sciences, Tuskegee University, Tuskegee, USA
(2)
Department of Agricultural and Environmental Sciences, Tuskegee University, Tuskegee, USA

References

  1. Simopoulos AP. The omega-6/omega-3 fatty acid ratio, genetic variation, and cardiovascular disease. Asia Pac J Clin Nutr. 2008;17(Suppl 1):131–4.PubMedGoogle Scholar
  2. Harris WS, Assaad B, Poston WC. Tissue omega-6/omega-3 fatty acid ratio and risk for coronary artery disease. Am J Cardiol. 2006;98:19–26.View ArticleGoogle Scholar
  3. Simopoulos AP. Omega-6/Omega-3 essential fatty acid ratio and chronic diseases. Food Rev Intl. 2004;20:77–90.View ArticleGoogle Scholar
  4. Riediger ND, Othman R, Fitz E, Pierce GN, Suh M, Moghadasian MH. Low n-6: n-3 fatty acid ratio, with fish-or flaxseed oil, in a high fat diet improves plasma lipids and beneficially alters tissue fatty acid composition in mice. Eur J Nutr. 2008;47:153–60.View ArticlePubMedGoogle Scholar
  5. Kearns RJ, Hayek MG, Turek JJ, Meydani M, Burr JR, Greene RJ, Marshall CA, Adams SM, Borgert RC, Reinhart GA. Effect of age, breed and dietary omega-6 (n-6): omega-3 (n-3) fatty acid ratio on immune function, eicosanoid production, and lipid peroxidation in young and aged dogs. Vet Immunol Immunopathol. 1999;69:165–83.View ArticlePubMedGoogle Scholar
  6. Simopoulos AP. Evolutionary aspects of omega-3 fatty acids in the food supply. Prostaglandins Leukot Essent Fatty Acids. 1999;60:421–9.View ArticlePubMedGoogle Scholar
  7. Simopoulos AP, Leaf A, Salem N Jr. Essentiality of and recommended dietary intakes for omega-6 and omega-3 fatty acids. Ann Nutr Metab. 1999;43:127–30.View ArticlePubMedGoogle Scholar
  8. Kris-Etherton PM, Taylor DS, Yu-Poth S, Huth P, Moriarty K, Fishell V, Hargrove RL, Zhao G, Etherton TD. Polyunsaturated fatty acids in the food chain in the United States. Am J Clin Nutr. 2000;71:179S–88S.View ArticlePubMedGoogle Scholar
  9. Simopoulos AP. Evolutionary aspects of diet, the omega-6/omega-3 ratio and genetic variation: nutritional implications for chronic diseases. Biomed Pharmacother. 2006;60:502–7.View ArticlePubMedGoogle Scholar
  10. Russo GL. Dietary n−6 and n−3 polyunsaturated fatty acids: from biochemistry to clinical implications in cardiovascular prevention. Biochem Pharmacol. 2009;77:937–46.View ArticlePubMedGoogle Scholar
  11. Hu FB. Plant-based foods and prevention of cardiovascular disease: an overview. Am J Clin Nutr. 2003;78:544S–51S.View ArticlePubMedGoogle Scholar
  12. Coulston AM. The role of dietary fats in plant-based diets. Am J Clin Nutr. 1999;70:512s–5s.View ArticlePubMedGoogle Scholar
  13. Kris-Etherton PM, Hecker KD, Bonanome A, Coval SM, Binkoski AE, Hilpert KF, Griel AE, Etherton TD. Bioactive compounds in foods: their role in the prevention of cardiovascular disease and cancer. Am J Med. 2002;113:71–88.View ArticleGoogle Scholar
  14. Lundberg JO, Feelisch M, Bjorne H, Jansson EA, Weitzberg E. Cardioprotective effects of vegetables: is nitrate the answer? Nitric Oxide. 2006;15:359–62.View ArticlePubMedGoogle Scholar
  15. de Lorgeril M, Salen P. The Mediterranean-style diet for the prevention of cardiovascular diseases. Public Health Nutr. 2006;9:118–23.View ArticlePubMedGoogle Scholar
  16. de Lorgeril M, Salen P. Modified Cretan Mediterranean diet in the prevention of coronary heart disease and cancer. World Rev Nutr Diet. 2000;87:1–23.View ArticlePubMedGoogle Scholar
  17. Huang Z, Wang B, Eaves DH, Shikany JM, Pace RD. Total phenolics and antioxidant capacity of indigenous vegetables in the Southeast United States: Alabama collaboration for cardiovascular equality project. Int J Food Sci Nutr. 2009;60:100-8.Google Scholar
  18. Huang Z, Wang B, Eaves DH, Shikany JM, Pace RD. Phenolic compound profile of selected vegetables frequently consumed by African Americans in the Southeast United States. Food Chem. 2007;103:1395–402.View ArticleGoogle Scholar
  19. Hu FB. Dietary pattern analysis: a new direction in nutritional epidemiology. Curr Opin Lipidol. 2002;13:3–9.View ArticlePubMedGoogle Scholar
  20. Fung TT, Chiuve SE, McCullough ML, Rexrode KM, Logroscino G, Hu FB. Adherence to a DASH-style diet and risk of coronary heart disease and stroke in women. Arch Intern Med. 2008;168:713–20.View ArticlePubMedGoogle Scholar
  21. Most MM. Estimated phytochemical content of the dietary approaches to stop hypertension (DASH) diet is higher than in the control study diet. J Am Diet Assoc. 2004;104:1725–7.View ArticlePubMedGoogle Scholar
  22. Sacks FM, Moore TJ, Appel LJ, Obarzanek E, Cutler JA, Vollmer WM, Vogt TM, Karanja N, Svetkey LP, Lin PH. A dietary approach to prevent hypertension: a review of the dietary approaches to stop hypertension (DASH) study. Clin Cardiol. 1999;22:6–10.View ArticleGoogle Scholar
  23. Oduro I, Ellis W, Owusu D. Nutritional potential of two leafy vegetables: Moringa oleifera and Ipomoea batatas leaves. Sci Res Essays. 2008;3:57–60.Google Scholar
  24. Johnson M, Pace RD. Sweet potato leaves: properties and synergistic interactions that promote health and prevent disease. Nutr Rev. 2010;68:604–15.View ArticlePubMedGoogle Scholar
  25. Johnson M, Pace RD, Dawkins NL, Willian KR. Diets containing traditional and novel green leafy vegetables improve liver fatty acid profiles of spontaneously hypertensive rats. Lipids Health Dis. 2013;12:168.View ArticlePubMedPubMed CentralGoogle Scholar
  26. Masood A, Stark KD, Salem N Jr. A simplified and efficient method for the analysis of fatty acid methyl esters suitable for large clinical studies. J Lipid Res. 2005;46:2299–305.View ArticlePubMedGoogle Scholar
  27. Makrides M, Neumann MA, Jeffrey B, Lien EL, Gibson RA. A randomized trial of different ratios of linoleic to α-linolenic acid in the diet of term infants: effects on visual function and growth. Am J Clin Nutr. 2000;71:120–9.View ArticlePubMedGoogle Scholar
  28. Ponder DL, Innis SM, Benson JD, Siegman JS. Docosahexaenoic acid status of term infants fed breast milk or infant formula containing soy oil or corn oil. Pediatr Res. 1992;32:683–8.View ArticlePubMedGoogle Scholar
  29. Putnam JC, Carlson SE, DeVoe PW, Barness LA. The effect of variations in dietary fatty acids on the fatty acid composition of erythrocyte phosphatidylcholine and phosphatidylethanolamine in human infants. Am J Clin Nutr. 1982;36:106–14.View ArticlePubMedGoogle Scholar
  30. Sun Q, Ma J, Campos H, Hankinson SE, Hu FB. Comparison between plasma and erythrocyte fatty acid content as biomarkers of fatty acid intake in US women. Am J Clin Nutr. 2007;86:74–81.View ArticlePubMedGoogle Scholar
  31. Farquhar JW, Ahrens EH Jr. Effects of dietary fats on human erythrocyte fatty acid patterns. J Clin Inves. 1963;42:675–85.View ArticleGoogle Scholar
  32. Barceló-Coblijn G, Murphy EJ, Othman R, Moghadasian MH, Kashour T, Friel JK. Flaxseed oil and fish-oil capsule consumption alters human red blood cell n–3 fatty acid composition: a multiple-dosing trial comparing 2 sources of n–3 fatty acid. Am J Clin Nutr. 2008;88:801–9.View ArticlePubMedGoogle Scholar
  33. Peet M, Murphy B, Shay J, Horrobin D. Depletion of omega-3 fatty acid levels in red blood cell membranes of depressive patients. Biol Psychiatry. 1998;43:315–9.View ArticlePubMedGoogle Scholar
  34. Stevens LJ, Zentall SS, Deck JL, Abate ML, Watkins BA, Lipp SR, Burgess JR. Essential fatty acid metabolism in boys with attention-deficit hyperactivity disorder. Am J Clin Nutr. 1995;62:761–8.View ArticlePubMedGoogle Scholar
  35. Parker G, Gibson NA, Brotchie H, Heruc G, Rees AM, Hadzi-Pavlovic D. Omega-3 fatty acids and mood disorders. Am J Psychiatry. 2006;163:969–78.View ArticlePubMedGoogle Scholar
  36. Osher Y, Belmaker R. Omega-3 fatty acids in depression: a review of three studies. CNS Neurosci Ther. 2009;15:128–33.View ArticlePubMedGoogle Scholar
  37. Severus WE, Littman AB, Stoll AL. Omega-3 fatty acids, homocysteine, and the increased risk of cardiovascular mortality in major depressive disorder. Harv Rev Psychiatry. 2001;9:280–93.View ArticlePubMedGoogle Scholar
  38. Joynt KE, Whellan DJ, O'Connor CM. Depression and cardiovascular disease: mechanisms of interaction. Biol Psychiatry. 2003;54:248–61.View ArticlePubMedGoogle Scholar
  39. Dolecek TA. Epidemiological evidence of relationships between dietary polyunsaturated fatty acids and mortality in the multiple risk factor intervention trial. Exp Biol Med. 1992;200:177–82.View ArticleGoogle Scholar
  40. Lavie CJ, Milani RV, Mehra MR, Ventura HO. Omega-3 polyunsaturated fatty acids and cardiovascular diseases. J Am Coll Cardiol. 2009;54:585–94.View ArticlePubMedGoogle Scholar
  41. von Schacky C. Omega-3 fatty acids and cardiovascular disease. Curr Opin Clin Nutr Metab Care. 2007;10:129–35.View ArticlePubMedGoogle Scholar
  42. Kris-Etherton PM, Harris WS, Appel LJ. Fish consumption, fish oil, omega-3 fatty acids, and cardiovascular disease. Circulation. 2002;106:2747–57.View ArticlePubMedGoogle Scholar
  43. Rizos EC, Ntzani EE, Bika E, Kostapanos MS, Elisaf MS. Association between omega-3 fatty acid supplementation and risk of major cardiovascular disease events: a systematic review and meta-analysis. JAMA. 2012;308:1024–33.View ArticlePubMedGoogle Scholar
  44. Simopoulos AP. Omega-3 fatty acids in inflammation and autoimmune diseases. J Am Coll Nutr. 2002;21:495–505.View ArticlePubMedGoogle Scholar
  45. Johnson M, Bradford C. Omega-3, omega-6 and omega-9 fatty acids: implications for cardiovascular and other diseases. J Glycomics Lipidomics. 2014;4:2153–0637.1000123.View ArticleGoogle Scholar
  46. Connor WE, Neuringer M, Lin DS. Dietary effects on brain fatty acid composition: the reversibility of n-3 fatty acid deficiency and turnover of docosahexaenoic acid in the brain, erythrocytes, and plasma of rhesus monkeys. J Lipid Res. 1990;31:237–47.PubMedGoogle Scholar
  47. Dunstan JA, Mori TA, Barden A, Beilin L, Holt P, Calder P, Taylor A, Prescott S. Effects of n-3 polyunsaturated fatty acid supplementation in pregnancy on maternal and fetal erythrocyte fatty acid composition. Eur J Clin Nutr. 2004;58:429–37.View ArticlePubMedGoogle Scholar
  48. Williams MA, Zingheim RW, King IB, Zebelman AM. Omega-3 fatty acids in maternal erythrocytes and risk of preeclampsia. Epidemiology. 1995;6(3):232–7.View ArticlePubMedGoogle Scholar
  49. Aydin R, Dogan I. Fatty acid profile and cholesterol content of egg yolk from chickens fed diets supplemented with purslane (Portulaca oleracea L.). J Sci Food Agric. 2010;90:1759–63.View ArticlePubMedGoogle Scholar
  50. Evaris E, Sarmiento-Franco LA, Segura-Correa J, Capetillo-Leal C. Effect of dietary inclusion of purslane (Portulaca oleraca L.) on yolk omega-3 fatty acids content. Egg quality and productive performance of Rhode Island red hens. Trop Subtrop Agroecosyst. 2015;18:33–8.Google Scholar
  51. Hamady G. Effects of different ratios of dietary omega-6 to omega-3 fatty acids on laying performance and egg quality of Lohmann Brown hens. Egypt Poult Sci J. 2013;33:957–69.Google Scholar
  52. Richard D, Kefi K, Barbe U, Bausero P, Visioli F. Polyunsaturated fatty acids as antioxidants. Pharmacol Res. 2008;57:451–5.View ArticlePubMedGoogle Scholar
  53. Calder PC. N− 3 polyunsaturated fatty acids and inflammation: from molecular biology to the clinic. Lipids. 2003;38:343–52.View ArticlePubMedGoogle Scholar
  54. Simopoulos AP. The importance of the Omega-6/Omega-3 fatty acid ratio in cardiovascular disease and other chronic diseases. Exp Biol Med. 2008;233:674–88.View ArticleGoogle Scholar
  55. Chajes V, Bougnoux P. Omega-6/omega-3 polyunsaturated fatty acid ratio and cancer. World Rev Nutr Diet. 2003;92:133–51.View ArticlePubMedGoogle Scholar
  56. Harris WS. The omega-6/omega-3 ratio and cardiovascular disease risk: uses and abuses. Curr Atheroscler Rep. 2006;8:453–9.View ArticlePubMedGoogle Scholar
  57. Kurata R, Kobayashi T, Ishii T, Niimi H, Niisaka S, Kubo M, Kishimoto M. Influence of sweet potato (Ipomoea batatas L.) leaf consumption on rat lipid metabolism. Food Sci Technol Res. 2017;23:57–62.View ArticleGoogle Scholar
  58. Nagai M, Tani M, Kishimoto Y, Iizuka M, Saita E, Toyozaki M, Kamiya T, Ikeguchi M, Kondo K. Sweet potato (Ipomoea batatas L.) leaves suppressed oxidation of low density lipoprotein (LDL) in vitro and in human subjects. J Clin Biochem Nutr. 2011;48:203–8.View ArticlePubMedPubMed CentralGoogle Scholar
  59. Ayeleso TB, Ramachela K, Mukwevho E. A review of therapeutic potentials of sweet potato: pharmacological activities and influence of the cultivar. Trop J Pharm Res. 2016;15:2751–61.View ArticleGoogle Scholar
  60. Noorbakhshnia M, Karimi-Zandi L. Portulaca oleracea L. prevents lipopolysaccharide-induced passive avoidance learning and memory and TNF-α impairments in hippocampus of rat. Physiol Behav. 2017;169:69–73.View ArticlePubMedGoogle Scholar
  61. Ramadan BK, Schaalan MF, Tolba AM. Hypoglycemic and pancreatic protective effects of Portulaca oleracea extract in alloxan induced diabetic rats. BMC Complement Altern Med. 2017;17:37.View ArticlePubMedPubMed CentralGoogle Scholar
  62. Miller-Cebert RL, Boateng J, Cebert E, Shackelford L, Verghese M. Chemopreventive potential of canola leafy greens and other cruciferous vegetables on Azoxymethane (AOM)-induced Colon Cancer in Fisher-344 male rats. Food Nutr Sci. 2016;7:964.Google Scholar
  63. Pollock RL. The effect of green leafy and cruciferous vegetable intake on the incidence of cardiovascular disease: a meta-analysis. JRSM Cardiovasc Dis. 2016;5:2048004016661435.PubMedPubMed CentralGoogle Scholar

Copyright

© The Author(s). 2018

Advertisement