Study design
This is a randomized, double-blind, placebo-controlled trial. The flowchart of the study protocol is illustrated in Figure 1. This study will be conducted at Human Nutrition Research Unit at Massey University, Palmerston North, New Zealand.
Sample size
The sample size calculation applies to CTX-II/ creatinine, CTX-II/ CPII ratio, and COMP as the primary outcome variables. For CTX-II/ creatinine as well as CTX-II/ CPII a sample size of 24 is required to detect a 20% difference from baseline with 80% power. Hence, 25 subjects will be recruited for each group (GSM and placebo). For COMP as well as CPII a sample size of 7 is required to detect a 20% difference from baseline.
Study population
Fifty apparently healthy postmenopausal women aged 55 to 75 years will be recruited by advertisement on campus and by using a recruitment agency, Trial Facts (https://trialfacts.com/). Written informed consent will be obtained from participants before commencing data collection.
Inclusion and exclusion criteria
For the present study, women who are at least five years postmenopausal (based on the natural cessation of menstruation), aged 55-75 years with no major illness, and body mass index (BMI) between 25 and 35 kg/m2 will be included in the study.
Patients will be excluded if: 1) they have a formal diagnosis of OA or rheumatoid arthritis (RA); 2) have chronic liver or renal disease, diabetes mellitus and atherosclerosis; 3) have history of allergy to mussels or seafood; 4) history of joint injury or trauma; 5) smoke or have alcohol intake more than two units per day; 6) receiving supplements for joint health, multivitamins/mineral or omega-3 regularly and unwilling to stop these four weeks before beginning of the trial; 7) currently being on hormone replacement therapy or less than 6 months prior beginning the trial; 8) Continuously taking anti-inflammatory drugs or glucocorticoids or NSAIDs on a daily basis.
Enrolment and washout period, randomization
Eligible participants will be asked to stop consumption of oily fish (salmon, sardines, pilchards, tuna, etc.), and mussels four weeks before the beginning the trial until the end of trial (from weeks - 4, to week 12). After 4 weeks of washout, participants will be randomly allocated into two groups: whole meat GSM powder (n=25) and placebo groups (n=25) and will be followed-up for 12 weeks. Participants will be randomized based on a double-blind randomization schedule and stratified randomization will be used to match participants based on age and BMI distribution. Table 1 shows the schedule of enrollment, interventions, and assessments.
Procedure
After screening for eligibility, the informed consent form will be obtained and both groups will be invited to the Human Nutrition Research Unit at Massey University, Palmerston North three times: at baseline, week 6, and after 12 weeks. Subjects will be interviewed regarding their socio-demographic, dietary intake and physical activity at baseline. At each visit, fasting blood and urine samples will be collected. A venous blood sample (20 ml) will be drawn after a 12-h overnight fast by a trained phlebotomist. Then blood samples will be centrifuged to obtain the serum and plasma EDTA and will be stored at −80 °C until further biochemical analyses. Body composition measurements including fat mass, lean mass and fat percentage will be measured and analyzed using the Hologic Horizon A, Dual energy X-ray Absorptiometry (DXA) at baseline and week 12.
Serum cartilage biomarkers CTX-II, COMP and CPII will be assessed using commercially available sandwich enzyme immunoassay kits (BioVendor Research and Diagnostic Products, Karasek, Czech Republic). Bone marker CTX-I will be analyzed by electrochemiluminescence immunoassay using the Roche COBAS® e411 system (Roche Diagnostics, Indianapolis, IN, USA).
Urinary CTX-II will be measured using enzyme immunoassay (IDS immunodiagnostic System, Fountain Hills, Arizona, USA). Cytokine concentrations will be analyzed using BioLegend® LEGENDplex™ Multi-Analyte Flow Assay, following the manufacturer’s instructions.To determine vitamin D status at the baseline, calcidiol (25-hydroxyvitamin D [25(OH) D]) will be analyzed using isotope-dilution liquid chromatography-tandem mass spectrometry (ID-LC-MSMS) by Canterbury Health, Christchurch, New Zealand. Serum iron, soluble transferrin receptors, transferrin, and ferritin will be measured to assess the iron status by measured at MedLab Central Palmerston North, New Zealand to provide information on iron status. Urine creatinine will also be assessed by the colorimetric method at Human Nutrition Research Unit at Massey University, Palmerston North, New Zealand. Creatinine will be used to correct the level of urinary CTX-II according to the urinary concentration.
Intervention
Spray-dried GSM powder will be produced by Sanford Ltd (ENZAQ facility, Blenheim, New Zealand) using standard manufacturing processes. The proximate composition and microbiological load will be assessed by a commercial testing laboratory (Food Testing Laboratory of Cawthron Analytical Services; Nelson, New Zealand). The Association of Official Analytical Chemists (AOAC) methods for crude protein (AOAC 981.10), total fat (AOAC 948.15), moisture at 105 oC (AOAC 950.46) and ash (AOAC 920.153) will be used and carbohydrate content will be determined by calculation (100% -% crude protein - % total fat- % moisture - % ash). An aliquot of the total lipid extract from the GSM powder will be analyzed by gas chromatography mass spectrometry (GC-MS) according to AOAC 963.22. The placebo (sunflower seed protein powder) capsules will be purchased by Sanford Ltd from a commercial supplier. Both GSM and placebo with be encapsulated in gelatin capsules by a commercial facility (Alaron, Nelson NZ) and stored under nitrogen in the dark until use. Each capsule will contain 0.5 g of whole meat GSM powder or sunflower seed protein powder. The capsules will be completely similar in the shape, size and color (which will be dark to hide contents). Whole meat GSM powder and placebo capsules will be provided to both groups for 12 weeks. Participants will be required to consume 6 capsules (3 grams total) per day with meals.
Compliance
To assess subject's compliance during the 12 weeks, diaries will be provided at the randomization to record the compliance to dietary and medication/supplement restriction. At the week 6 and 12, subjects will return their unused capsules to researcher to assess the rate of the compliance. At weeks 6 and 12 consumption record diaries will be cross-checked with subjects. At the baseline and week 12, the plasma and erythrocyte membrane fatty acids will also be measured as indicator to assess the adherence to study protocol.
Safety
Subjects will be monitored closely during the study period and will be provided with daily diary to record all the medications taken and any occurrence of adverse events at weeks 6 and 12, the principal investigator will cross-check the recorded diaries with subjects. Routine laboratory measurements including liver and kidney function tests, blood glucose (non-fasting) and lipid profile (triglyceride, total cholesterol, HDL-cholesterol, LDL-cholesterol) will be performed at time of enrolment and after 12 weeks of treatment at MedLab Central Palmerston North, New Zealand by the certified phlebotomist. In case of any side effects or blood abnormalities, the person will be withdrawn and referred to their general practitioner for further examination.
Study outcomes
Primary outcomes
The changes in cartilage turnover markers; (CPII, COMP, CTX-II), bone resorption marker (CTX-I), measured at the end of the study in comparison with the week 6 and baseline values.
Secondary outcomes
The changes in inflammatory markers including hs-CRP and 13 cytokines namely IL-1β, interferon alpha-2 (IFN-α2), IFN-λ, TNF-α, monocyte chemoattractant protein-1 (MCP-1), IL-6, IL-8, IL-10, IL-12p70, IL-17A, IL-18, IL-23 and IL-33, as well as serum soluble transferrin receptor levels as an indicator of iron status measured at the end of the study in comparison with baseline values. Changes in body composition including fat mass (FM), lean mass (LM) and fat percentage, joint pain and knee function will also be measured.
Assessment of dietary intake
The New Zealand polyunsaturated fatty acids questionnaire will be applied to assess the habitual polyunsaturated fatty acids intake of participants after enrollment. To measure participants’ dietary intake, a 3-day diet diary (3-DDD) over non-consecutive days (including one weekend day) will be collected three times during the study. The 3-DDD will be used to collect information on participants’ food and beverage intake using household measurement tools to assist subjects in estimating the portion sizes of the food. Brand name of food products, recipes and method of food preparation will be described. Dietary intake will be analyzed with Food works 9 professional, Xyris software.
Assessment of physical activity
Physical activity will be assessed using the New Zealand Physical Activity Questionnaire-short form (NZPAQ-SF) [19]. The NZPAQ has previously been validated by Boon et al. Physical activity will be measured by METs-min/day which is computed by using the scoring protocol of IPAQ for continuous score [20]. MET values and formula for calculation of MET-minutes will be assessed and used as below:
- Walking MET-minutes/week at work = 3.3 × walking minutes × walking days at work
- Moderate MET-minutes/week at work = 4.0 × moderate-intensity activity minutes × moderate intensity days at work.
- Vigorous MET-minutes/week at work = 8.0 × vigorous-intensity activity minutes × vigorous
- Total Work MET-minutes/week = sum of Walking + Moderate + Vigorous MET-minutes/week scores at work
Assessment of joint pain and knee function
Subjects will be provided an assessment of their joint pain level using the 100 mm Visual Analog Scale (VAS) at six-week intervals.
Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire will be used to measure a subject's opinion about their knee and associated problems [21]. The KOOS consists of 42 questions, which cover five domains. These include 1) pain frequency and severity during functional activities; 2) severity of knee stiffness and swelling, grinding or clicking, catching, and limitation in range of motion; 3) difficulty in performing the daily living activities; 4) difficulty experienced during sport and recreational activities; and 5) knee-related quality of life (QOL).
All items are scored on a 5-point Likert scale (0–4). The five dimensions are scored separately as the sum of all corresponding items. Scores are then converted to a 0–100 scale (percentage of total possible score obtained), where zero represents extreme knee problems and 100 represents no knee problems.
Statistical analysis
Statistical analysis will be performed using IBM statistics software version 25 (Armonk, NY, USA). The values of variables will be presented as mean ± standard deviation. Normality tests will be assessed through Shapiro-Wilk tests carried out on each parameter before analysis. All outcome variables will be assessed based on per protocol analysis. To compare the mean differences between the two groups, independent t-test and Mann–Whitney will be used for normal and non-normal data respectively, considering the normality of data.