ORIGINAL RESEARCH

The Effect of Sea Buckthorn Supplement on OralHealth, Inflammation, and DNA Damagein Hemodialysis Patients: A Double-Blinded,Randomized Crossover StudyYlva Rodhe, MSc, Lic Med Sci,* Therese Woodhill, MSc,* Royne Thorman, DDS, PhD,†

Lennart M€oller, PhD,* and Britta Hylander, MD, PhD‡

Objective: Chronic kidney disease is associated with inflammation, oxidative stress, malnutrition, poor oral health, and mouth

dryness. The objective of this study was to evaluate effects of sea buckthorn oil (SBO) extract, which is rich in vitamins, phytochemicals,

and polyunsaturated fatty acids, on oxidative stress, saliva production, and inflammation in hemodialysis patients.

Design Setting and Subjects: This was a randomized, double-blinded, and placebo-controlled crossover study (2 3 8 weeks,

4-weekwashout). The study subjects were hemodialysis patients (n5 45) recruited from the Department of RenalMedicine at Karolinska

University Hospital in Stockholm.

Intervention and Main Outcome Measures: The patients received 4 capsules per day, each containing 500 mg of SBO or placebo,

for 8 weeks. They were then crossed over to the other treatment after a 4-week washout period. Salivary gland biopsies, saliva, and

blood samples were collected before and after each treatment period. Main outcomes were DNA breaks and oxidative DNA lesions

in minor accessory salivary glands, salivary flow rates, and inflammation markers in blood (high-sensitivity C-reactive protein, antitryp-

sin, orosomucoid in plasma, leukocytes in blood). Blood markers including creatinine, urea in plasma, and hemoglobin in blood were

investigated.

Results: The results showed no significant changes in DNA breaks, oxidative DNA lesions, salivary flow rates, or inflammation after

SBO supplementation. However, plasma levels of phosphate and sodium increased and plasma levels of iron decreased.

Conclusion: In conclusion, SBO supplementation as performed in this study did not protect against oxidative stress, nor improve oral

health or inflammation status in hemodialysis patients.

� 2013 by the National Kidney Foundation, Inc. All rights reserved.

Introduction

CHRONIC KIDNEY DISEASE (CKD) is a progres-sive loss of renal function accompanied by increasing

uremic symptoms. Uremia is associated with malnutrition,high levels of oxidative stress, and inflammation, thus con-tributing to a higher risk of developing cardiovasculardiseases, atherosclerosis, and cancer.1-3 In addition, CKDpatients often suffer from oral health problems asa consequence of the disease and dialysis. Many patientsexperience xerostomia (mouth dryness) and eating and

*Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge,

Sweden.†Department of Dental Medicine, Danderyd Hospital, Karolinska Institutet,

Stockholm, Sweden.‡Department of Nephrology, Karolinska University Hospital, Karolinska In-

stitutet, Stockholm, Sweden.

Financial Disclosure: The study was initiated and partially supported by Scan-

dinavian Clinical Nutrition AB.

Address correspondence to Lennart M€oller, PhD, Department for Biosciences

and Nutrition, Karolinska Institutet, SE-141 83 Huddinge, Sweden.

E-mail: lennart.moller@ki.se� 2013 by the National Kidney Foundation, Inc. All rights reserved.

1051-2276/$36.00

http://dx.doi.org/10.1053/j.jrn.2012.08.006

172

speaking difficulties because of poor salivation, caries,periodontitis, altered salivary constitution, and mucosalchanges.4-6 Disorder in the oral cavity is considered tocontribute to the systemic inflammatory state with anincreased risk of cardiovascular diseases.7

Oxidative stress is a process that has been implicated inmany diseases, including CKD, and is an imbalancebetween oxidant species and the antioxidative defensesystem. Because of malnutrition and dialysis treatment, di-alysis patients have an insufficient antioxidative defense.8,9

There are several biomarkers of oxidative stress, andoxidative DNA damage is a common one as well asa possible marker for cancer risk.10 One established methodto measure DNA damage is the comet assay, and severalstudies have shown increased levels of damage to DNA inlymphocytes from CKD patients using this method.11,12

The comet assay can also be modified by adding specificenzymes to detect oxidative DNA damage.13

Sea buckthorn, a plant with high levels of unsaturatedfatty acids and antioxidants, has been attributed anticancereffects, anti-inflammatory effects, immune response regula-tory effects, and antioxidative properties.14-18 Oil from thisplant is rich in linoleic (18:2 n-6), a-linolenic (18:3 n-3),

Journal of Renal Nutrition, Vol 23, No 3 (May), 2013: pp 172-179

Table 1. Content (mass and weight %) in SBO Capsulesand the Daily Dose

Content1 SBO Capsule

(500 mg)Daily Dose

(4 capsules, 2 g)

Oleic acid (C18:1 n-9) 124 mg (24.8%) 496 mg

Palmitoleic acid

(C16:1 n-7)

97 mg (19.5%) 388 mg

Linoleic acid(C18:2 n-6)

92 mg (18.4%) 368 mg

a-linolenic acid

(C18:3 n-3)

63 mg (12.6%) 252 mg

Vitamin E 931 mg 3.7 mg

Vitamin A 88 mg 352 mg

Figure 1.Crossover study design with two sequence groups:AB (SBO in the first treatment period) and BA (placebo in thefirst treatment period).

EFFECTS OF SEA BUCKTHORN OIL IN CKD PATIENTS 173

oleic (18:1 n-9), palmitoleic (16:1 n-7), and palmitic (16:0)acids.19 The oil is also rich in vitamin E, tocopherols (a andg), tocotrienols, flavonoids, and carotenoids (mainly b-car-otene). Intervention studies with sea buckthorn oil (SBO)have reported improvement of symptoms related to dryeyes sometimes associated with Meibomian gland dysfunc-tion.20,21 Skin diseases have also been reported to bepositively affected by SBO.22 Dietary supplementation isoften discussed as a tool to improve health and reduceoxidative stress and inflammation. Despite the uncertaintyin efficiency of dietary supplementation in the general pop-ulation, certain risk groups with insufficient antioxidantdefense might be positively affected.23,24 Studies onsupplementation with omega-3 fatty acids have beenreported to enhance antioxidative defense and improvebiomarkers of oxidative stress in CKD patients.25,26

The objective of this study was to evaluate whether sup-plementation with SBO could improve oral health and re-duce oxidative stress levels in local tissue and inflammationstatus in hemodialysis patients. Main outcomes in this studywere the DNA damage in minor salivary glands, salivaryflow rate, and inflammation markers. Analyses of bloodmarkers from routine samples of hemodialysis patientswere also included in the study.

MethodsSubjectsHemodialysis patients (N5 72) were recruited from the

Department of Renal Medicine at Karolinska UniversityHospital in Stockholm. The inclusion criteria were ageover 19 years, hemodialysis treatment for more than3 months, stable medication, and original teeth. Patientswith dysphagia, active hepatitis, or prior detection ofmethicillin-resistant Staphylococcus aureus infection were ex-cluded. Sixty-three patients fulfilled the inclusion criteriaand were enrolled in the study.

Supplement MaterialCommercially available SBO from supercritical carbon

dioxide (CO2) extraction of fruit flesh and seeds of Hippo-phae rhamnoides L. was used. The content in one capsulecontaining 500 mg of SBO extract and the daily dose arepresented in Table 1. The placebo capsules contained coco-nut oil and were similar in appearance.

Study DesignThis study was a randomized, double-blinded, crossover

study with 2 8-week treatment periods and a 4-weekwashout period between the treatments. The study wasstarted in June 2007 and ended in January 2008. Each setof capsules, one container with SBO capsules and onewith placebo capsules, was distributed with an identifica-tion number and a treatment sequence (AB or BA). Thepatients were then randomly assigned an identificationnumber and the corresponding set of capsules, resultingin 2 patient groups with different treatment sequence.

The AB group received SBO during the first period andplacebo capsules during the second period; the BA groupreceived placebo capsules during the first period and SBOduring the second period. Neither the patients nor theexaminer knew to which sequence group the patients be-longed. Of the 63 hemodialysis patients that were enrolledin the study, 45 patients completed the study. The studydesign is presented in Figure 1. The daily dose consistedof 4 capsules (4 3 500 mg) per day. The appointmentsfor taking blood samples and biopsies of glands were con-ducted 4 times before and after each treatment period. Todiminish the risk of fluctuations in salivary secretion andhydration status, the samples were collected before noonand immediately before dialysis treatment. The patientswere assumed to remain stable during the study, and thewashout period was assumed to be sufficiently long toavoid carryover effects. The study was approved by theEthics Committee for Human Research of the KarolinskaInstitutet and was conducted in accordance with theHelsinki Declaration (2004).

Table 2. Characteristics and Diagnoses of theHemodialysis Patients Included in the Crossover Study

CharacteristicsHemodialysis Patient

Group (n 5 45)

Patient characteristics

Age (years) 62 6 14

Sex (% males) 64

Tobacco users (%) 31Diagnoses

Diabetes mellitus 11 (24%)

Glomerulonephritis 6 (13%)Renal vascular disease 8 (18%)

Pyelonephritis and interstitial

nephritis

4 (9%)

RODHE ET AL174

DNA Damage MeasurementsCollection of minor accessory salivary glands and analysis

of DNA damagewas performed according to Ersson et al.27

Briefly, at each appointment a biopsy of salivary gland tissuewas removed by incision (number 15 scalpel, Braun, Tut-tlingen, Germany) and frozen at 270�C until analyzed bythe comet assay. Before DNA analysis, the glands werethawed and homogenized in phosphate-buffered salineusing a Dounce B Pestle. The cells were mixed with low-melting-point agarose and spread on glass slides. After60minutes of cell lysis at a pHof 10, the slideswere preparedfor 30 minutes of treatment with FormamidoPyrimidineDNA Glycosylase. The enzyme treatment and subsequentalkaline treatment for 40 minutes resulted in additionalstrand breaks due to recognition and removal of specific ox-idatively damaged purines, creating apurinic sites. Under anelectric field for 30 minutes, DNA loops were extended asa consequence of DNA breaks. Staining of the DNAwithethidium bromide allowed visualization of comets and anal-ysis of the percentage DNA in tail using a fluorescence mi-croscope and computerized image analysis (Komet 4.0;Kinetic Imaging Ltd., Bromborough, United Kingdom).One hundred and five cells (i.e., 35 cells in each of 3 fieldson the microscope slide) were scored per sample, andeach glandwas analyzed in duplicate, with andwithout For-mamidoPyrimidine DNAGlycosylase treatment, to obtainan estimation of the level of migrated DNA in terms ofstrand breaks and alkali-labile sites in the nontreated slidesand oxidative DNA lesions in the enzyme-treated slides.The stability of the method was verified by analyzing 1 ali-quot of peripheral blood mononuclear cells from onehealthy blood donor for each run of analysis.

Salivary Secretion MeasurementsThe volume of secreted saliva was measured at rest and

after stimulation according to the draining method andthe masticatory method, as described by Thorman et al.28

Tomeasure the saliva volume at rest, the patients were askedto lean forward and achieve a passive flow of saliva withoutmasticatory movements for 15 minutes. For the stimulatedsaliva volume measurement, the patients were instructed tochew a paraffin capsule, and the produced saliva was col-lected for 5 minutes. The collected saliva volume was mea-sured and the salivary flow rates were expressed in millilitersper minute.

Blood MeasurementsVenous blood samples were collected before and after

each treatment period. The following parameters weremeasured (P indicates plasma and B indicates blood levels):P-high sensitivity C-reactive protein (hs-CRP), P-anti-trypsin, P-orosomucoid, B-leukocytes, P-albumin, P-cal-cium, P-phosphate, P-potassium, P-sodium, P-creatinine,P-urea, P- CO2, P-glucose, P-haptoglobin, B-hemoglo-bin, B-thrombocytes, P-transferrin, P-immunoglobulin

A, P-immunoglobulin G, P-immunoglobulin M, P-iron,and P-iron saturation.

Statistical AnalysisThe software SPSS version 19.0 (IBM SPSS, Inc., Chi-

cago, IL) was used to perform the statistical analysis. Sha-piro-Wilk’s test was used to evaluate the distributions ofthe data. Because of normal and non-normal distributions,parametric and nonparametric statistical methods wereused. Values before and after SBO supplementation or pla-cebo were compared with paired 2-sample student’s t test(normal distributions) or Wilcoxon signed rank test (non-normal distributions). Only subjects that completed thestudy and had baseline and after values in the treatmentperiod were included in the statistical analysis. Possible car-ryover or period effects were investigated by comparing thesum and the differences of the responses for each sequencegroup (AB or BA) with unpaired 2-sample student’s t test orMann-Whitney.29 P values less than .05 were consideredstatistically significant. No adjustment for multiple testingwas made.

ResultsForty-five patients completed the study and patient char-

acteristics can be seen inTable 2. Effects of SBOsupplemen-tation or placebo treatment on DNA damage, salivary flow,and inflammation markers are presented in Table 3 as databefore and after treatment. Other laboratory data are pre-sented in Table 4. The baseline values represent measuredvalues before each treatment period. Because of normaland non-normal distributions, descriptive data are pre-sented in mean, median, minimum, and maximum values.

DNA DamageNo significant changes were seen in DNA damage dur-

ing the intervention (Table 3). The baseline value of DNAstrand breaks and alkali-labile sites was 5.2% DNA in tail,and the levels did not change significantly after SBO sup-plementation or placebo treatment. The baseline valuefor oxidative DNA lesions before SBO supplementationwas 7.7% DNA in tail, and there were no significant

Table

3.DNADamage,Salivary

Secretion,andInflammationMarkers

Before

andAfterOralSupplementationWithSBO

andPlaceboOil

MeasuredParameters

SBO

Supplement

PlaceboTreatm

ent

Before

After

Before

After

Mean

Median

Min-M

ax

Mean

Median

Min-M

ax

PMean

Median

Min-M

ax

Mean

Median

Min-M

ax

P

DNAdamage

DNAstrandbreaks/alkali-labile

sites(%

DNAin

tail)

5.5

5.2

3.4-9.4

5.3

5.1

3.7-8.4

.23*

5.5

5.2

3.6-13.2

5.9

5.3

3.6-11.5

.20*

OxidativeDNAlesions

(%DNAin

tail)

9.1

7.7

6.4-43.5

8.9

8.8

5.4-13.6

.12*

9.0

8.8

4.6-24.2

8.6

8.2

4.1-13.7

.89†

Salivary

secretion

Secretionrate,atrest(m

L/m

in)

0.1

0.1

0.0-0.6

0.1

0.0

0.0-0.8

.29*

0.1

0.1

0.0-0.5

0.1

0.1

0.0-0.9

.23*

Secretionrate,stimulated(m

L/m

in)

1.0

0.9

0.0-2.5

1.0

0.9

0.0-3.0

.46†

1.1

1.1

0.0-2.4

1.1

0.9

0.0-3.3

.97*

Inflammationmarkers

hsCRP(m

g/L)

6.7

4.2

0.2-65.0

9.4

5.4

0.4-77.2

.24*

10.1

5.0

0.4-77.0

9.0

4.5

0.2-95.9

.63*

Antitrypsin

(g/L)

1.5

1.4

0.9-2.3

1.5

1.5

0.6-2.4

.48†

1.5

1.6

0.8-2.1

1.5

1.5

0.7-2.1

.37†

Orosomucoid

(g/L)

1.0

1.0

0.6-2.1

1.0

1.0

0.6-1.8

.55*

1.1

1.0

0.4-2.0

1.0

1.0

0.6-1.6

.31*

Leukocytes(109/L)

7.2

6.8

1.8-14.6

7.1

6.9

2.8-11.2

.93*

7.1

7.1

2.6-11.0

7.1

6.8

0.6-12.6

8.02†

*Non-norm

ald

istribution.

†Norm

ald

istribution.

EFFECTS OF SEA BUCKTHORN OIL IN CKD PATIENTS 175

changes after treatment. There were no significant carry-over effects or period effects.

Salivary Flow RatesThere were no significant changes in salivary excretion

rates during the intervention (Table 3). Median values forsaliva production before SBO supplement were 0.1 mL/minute at rest and 0.9 mL/minute during stimulation.No carryover or period effects were observed.

Inflammation ParametersThere were no significant changes in the inflammation

markers P-hs-CRP, P-antitrypsin, P-orosomucoid, or B-leukocytes after SBO supplementation (Table 3). However,there was a significant difference between the sequencegroups (P 5 .001). The AB sequence group P-hs-CRPlevels increased 3.05 mg/L, whereas that of the BAsequence group decreased 0.50 mg/L after SBO supple-mentation. The same pattern was seen in the P-orosomu-coid levels (P 5 .03): the AB group increased 0.09 g/Land the BA group decreased 0.02 g/L. Baseline concentra-tion of P-antitrypsin was 1.40 g/L before supplementationand did not change significantly after SBO supplementationor placebo. No carryover effect was observed for any of theinflammation parameters.

Blood ParametersP-creatinine and P-urea did not change significantly after

SBO treatment (Table 4). However, there was a significantincrease in creatinine (P5.03) and urea (P5.01) levels afterplacebo treatment. SBO supplementation significantly in-creased P-phosphate (P 5 .02) and P-sodium levels (P 5.02), and it significantly reduced the P-iron (P5.05) level.P-CO2 levels were not affected by SBO supplementation.However, there was a significant decrease after placebotreatment (P 5 .004). In contrast, levels of P-potassium(P5.03), P-immunoglobulin A (P5.04), and P-immuno-globulin M (P 5 .01) were increased after placebo treat-ment. The levels of P-albumin, P-calcium, P-glucose,P-haptoglobin, B-hemoglobin, B-thrombocytes, P-trans-ferrin, P-immunoglobulin G, and iron saturation werenot affected by SBO supplementation or placebo. A carry-over effect was observed for P-iron levels, but not for anyother blood parameter. Period effects were observed forP-CO2, P-calcium, and P-potassium levels.

DiscussionThe main objective of this study was to investigate any

changes in oral health, DNA damage, and inflammatorystate in hemodialysis patients after dietary supplementationwith SBO. Our crossover study did not show any effects ofthis supplement onDNA strand breaks/alkali-labile sites, oroxidative DNA lesions in minor salivary glands, nor on sal-ivary flow rates or in measured inflammatory parameters.However, plasma levels of phosphate, sodium, and ironwere affected by SBO whereas plasma levels of potassium,

Table 4. Laboratory Data for Blood Markers Before and After Oral Supplementation With SBO and Placebo Oil

Blood Markers

SBO Supplement Placebo Treatment

Before After Before After

Mean Median Min-Max Mean Median Min-Max P Mean Median Min-Max Mean Median Min-Max P

Blood markers

Albumin (g/L) 34.3 35.0 21.0-44.0 34.3 34.0 25.0-44.0 .68* 34.4 34.0 22.0-43.0 34.6 35.0 25.0-41.0 .60†Calcium (albumin-corrected)

(mmol/L)

2.4 2.5 1.9-1.9 2.4 2.4 1.7-3.1 .43† 2.4 2.5 2.1-2.9 2.5 2.5 2.2-2.7 .43†

Phosphate (mmol/L) 1.5 1.5 0.8-2.5 1.7 1.7 0.9-2.7 ‡ 1.7 1.6 0.9-3.2 1.8 1.8 0.9-3.1 .46*Potassium (mmol/L) 5.1 5.2 2.8-6.9 5.0 4.9 3.2-9.6 .36* 5.0 4.9 3.1-6.6 5.4 5.4 3.7-8.4 ‡

Sodium (mmol/L) 138 137 132-146 139 138 132-146 *,‡ 138 138 131-150 138 138 128-143 .54†

Creatinine (mmol/L) 746 690 345-1,293 761 765 384-1,308 .39† 719 693 346-1,078 774 751 400-1,402 ‡

Urea (mmol/L) 22.2 21.2 6.0-47.8 22.9 22.8 8.9-39.7 .40* 21.8 22.0 8.2-40.0 24.5 24.6 10.9-54.3 *,§

CO2 (mmol/L) 24.3 24.0 15.0-32.0 23.9 24.0 19.0-30.0 .39* 24.4 24.0 20.0-29.0 23.1 24.0 14.0-29.0 *,§

Glucose (mmol/L) 5.9 5.4 4.1-11.0 5.9 5.4 2.2-11.0 .99* 6.0 5.4 4.2-11.0 6.3 5.2 3.9-20.2 .40*

Haptoglobin (g/L) 1.1 1.0 0.1-2.9 1.2 1.1 0.1-2.5 .30† 1.3 1.2 0.1-2.7 1.2 1.2 0.1-2.7 .61†

Hemoglobin (g/L) 120 120 95-156 120 122 89-145 .82† 120 121 94-149 123 123 91-159 .27†Thrombocytes (109/L) 218 214 54-374 221 212 70-389 .61† 213 189 59-343 211 204 106-395 .81*

Transferrin (g/L) 1.8 1.8 0.8-2.7 1.8 1.8 1.0-2.6 .87† 1.8 1.8 1.1-2.6 1.8 1.8 1.1-2.9 .15†

Immunoglobulin G (g/L) 2.6 2.5 0.1-6.4 2.7 2.4 0.1-6.3 .46* 2.7 2.6 0.1-5.6 2.8 2.5 0.1-6.3 ‡

Immunoglobulin A (g/L) 11.3 11.0 4.8-21.9 11.6 10.8 5.5-24.1 .13* 11.2 10.7 4.9-22.0 11.4 10.9 5.4-5.4 .33†

Immunoglobulin M (g/L) 0.7 0.7 0.1-3.5 0.8 0.7 0.2-3.8 .21* 0.7 0.7 0.1-3.2 0.8 0.7 0.1-3.6 *,§

Iron (mmol/L) 12.0 11.0 4.0-32.0 10.7 10.0 5.0-25.0 *,‡ 12.2 11.0 5.0-38.0 11.4 10.0 7.0-22.0 .74*

Iron saturation 0.3 0.2 0.1-0.7 0.2 0.2 0.1-0.6 .05* 0.3 0.2 0.1-0.7 0.3 0.2 0.1-0.6 .73†

*Non-normal distribution.

†Normal distribution.

‡Significant levels: P , .05.

§Significant levels: P , .01.

RODHEETAL

176

EFFECTS OF SEA BUCKTHORN OIL IN CKD PATIENTS 177

creatinine, urea, CO2, immunoglobulin A, and immuno-globulin M were affected by placebo.In CKD, the kidney’s capacity is reduced, a process that is

irreversible. The restricted diet and the dialysis treatment ofhemodialysis patients alter the vitamin levels in the blood,and dietary supplementation is common. The administra-tion of water-soluble vitamins in hemodialysis patients dif-fers greatly among countries. Fissell et al.30 report that most(71.9%) of the hemodialysis patients in the United Stateswere administered water-soluble vitamins whereas admin-istration in the United Kingdom was less common (3.7%).However, it is unclear whether dietary supplements couldsignificantly improve clinical parameters associated withthe disease. In the current study, SBO supplementationdid not improve most of the analyzed parameters directlyassociated with hemodialysis treatment, such as creatinine,urea, and calcium. Our hypothesis that SBO could improveoral health was based on previous studies on this plant.Larmo et al.20 and Jarvinen et al.21 showed that SBO de-creased symptoms in dry eyes in patients suffering fromsuch problems, and they proposed an effect on local ocularinflammation because they could not detect any changes inthe composition of fatty acids in the tear film. Therefore,interest was drawn to whether SBO could amelioratemouth dryness and improve oral health in CKD patients.In the study presented here, we monitored mouth drynessin dialysis patients by measuring their salivary flow rate atrest and after stimuli because a low salivary flow rate hasbeen associated with dry mouth symptoms and oral prob-lems.31 However, supplementation with SBO did not im-prove the salivary flow rate in the study presented here.Good function of the minor salivary glands is important

for salivary secretion.32 Changes in the saliva could lead tocomplaints in the oral cavity,31 which in turn can contrib-ute to systemic inflammation. In CKD patients, this may bean extra burden to the already strained inflammatory state.In the study presented here we assessed local damage, ana-lyzing DNA damage (strand breaks/alkali-labile sites andoxidative DNA lesions) in minor salivary glands. Studieshave shown that CKD causes DNA damage to circulatingmononuclear cells, and the aim was to investigate the effectof supplementation on the level of DNA damage in salivaryglands, a peripheral tissue that is exposed to dietary intake ofantioxidants and essential fatty acids. Again, the SBO sup-plement was ineffective and the level of DNA damage didnot change after supplementation. However, the level ofoxidative DNA lesions in minor salivary glands amongthe patients studied were not high; instead, they were lowercompared with matched controls, as seen by previous re-sults.27 A proposed mechanism was an upregulated repairsystem in peripheral tissue due to an increased systemicinflammation. Low levels of DNA damage might not be af-fected by supplementation with antioxidative and protec-tive food agents, but elevated levels of DNA damagemight be.

Inflammatory levels are well known to be elevated in he-modialysis patients and contribute to the increased risk ofinflammatory diseases. During inflammation, reactive oxy-gen species are generated that contribute to an increasedoxidative stress level. Hence, interrelations between inflam-mation and oxidative stress exist, and oxidative damage toDNA, lipids, and proteins is known to contribute to diseasedevelopment and progress. Despite elevated levels of in-flammation in the patient group (shown in our previousstudy27), we did not see any effect on inflammation param-eters after SBO extract intake. Larmo et al.33 have reporteda small decrease in CRP levels after intake of puree fromwhole sea buckthorn. In the study presented here, seabuckthorn was administered in the form of encapsulatedextracted SBO; therefore, the different production proce-dures and administered forms may have contributed to dif-ferences in the content of fatty acids, antioxidants, andother components, possibly lowering the level of less lipo-philic compounds. In addition, the subspecies, area, andyear of cultivation also affect the content in SBO. Sea buck-thorn has been used as a medicinal plant for several hundredyears in primarily China, Russia, and Turkey. Indeed, sci-entific studies have reported sea buckthorn to have inhibit-ing effects on ADP-induced platelet aggregation34 as well aspositive effects on metabolic disease parameters, decreasedwaist circumstances and cellular adhesion,35 and symptomsof dry eyes.20 In vitro studies have also revealed antioxidantproperties of different extracts.36,37 However, publishedclinical studies are not consistent in showing effects oninflammatory markers. The results from our studyemphasize the complexity in the question of dietarysupplementation. Diets rich in vegetables and fruits showinverse correlations with cancer and cardiovascular risk inepidemiological studies38,39 whereas intervention studiesadministering dietary supplements to the generalpopulation often fail to show beneficial effects. Botha lack of effect,40 and even harmful effects, with an increas-ing cancer risk41 have been presented.In contrast to the main outcomes, some of the blood

markers were significantly affected by supplementationwith SBO during the intervention presented here. In thesupplementation group, the plasma level of iron was re-duced and the sodium and phosphate in plasma were in-creased. Reduced iron levels can be harmful because irondeficiencymight lead to anemia. Higher levels of phosphatecan influence vascular calcification, which is a risk factor fordeveloping atherosclerosis and cardiovascular disease.42

However, changes were small, and the clinical relevanceof these changes can be questioned. The placebo did infact also alter some parameters. Coconut oil was used as pla-cebo, and it cannot be excluded that some component ofthis oil did in fact influence some of the uremic parametersamong these patients.When analyzing for carryover and period effects, the P

values were not adjusted according to Bonferroni (multiple

RODHE ET AL178

comparisons). If adjustments had been carried out, a major-ity of the observed period effects had been statistically insig-nificant. On the basis of the lack of a carryover effect of mostparameters (only 1 of 26 parameters was subject to carryovereffect), the 4-week-longwashout period seems to have beensufficient. Therewere also 18dropouts (2 deaths, 3 noncom-pliant patients, and 13 cases of acute illness) in this study thatlimited the outcome.

In conclusion, SBO supplementation did not protectagainst DNA damage or oxidative stress, nor did it improvethe salivary secretion or inflammatory markers of the stud-ied CKD patients undergoing hemodialysis.

Practical ApplicationThe results from the study presented here showed no

beneficial health effects of dietary supplementation withSBO. In conclusion, SBO do not protect against DNAdamage or oxidative DNA damage in salivary glands underthe conditions of this study, nor did it affect the salivary se-cretion or inflammation in hemodialysis patients.

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