Creatine, Carnitine and Carnosine in Vegetarians

Dietary Modification Clinical Trial

Official title:

Effect of a 6-month Vegetarian Diet in Omnivorous Women on Body Creatine, Carnitine and Carnosine Stores

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT03194334
• Other study ID #: EC/2012/666
• Status: Completed
• Phase: N/A
• Start date: December 2012
• Est. completion date: June 2013

Study information

• Verified date: October 2018
• Source: University Ghent
• Contact: n/a
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial Summary

Balanced vegetarian diets are popular and contain health-promoting characteristics. A balanced lacto-ovo-vegetarian diet differs in nutrient intake from an omnivorous diet, e.g. by increased intake of fibre, magnesium and antioxidants, but lower intake of omega-3 fatty acids and vitamin B12. However, the impact of reduced to near absent intake of carnitine, carnosine and creatine in a vegetarian diet is less well established and could be relevant in relation to muscle function, exercise capacity and sports performance. Few longitudinal intervention studies investigating the effect of a vegetarian diet on the availability of these compounds currently exist.

This study aimed therefore to investigate the effect of of transiently switching omnivores onto a vegetarian diet for 6 months on muscle and plasma creatine, carnitine and carnosine homeostasis.

We hypothesized that homeostasis of creatine and carnosine would be disrupted when their dietary intake was missing. For carnitine, however, we hypothesized that homeostasis can be maintained given its slow turnover rate and its presence in some non-meat nutrients. A second aim was to investigate whether supplementation of creatine and beta-alanine (the rate-limiting precursor of carnosine synthesis), concurrently with a lacto-ovo-vegetarian diet, was able to correct for potentially emerging deficiencies.

Description:

Forty healthy female omnivores will be included in this 6-month intervention study. Exclusion criteria are smoking, chronic use of medication, athletes participating in competitions, vegetarianism or eating meat or fish less than 5 times a week. The study is scheduled over a period of 6 months and measurements will be performed 1 week prior to the intervention (0M), after 3 months (3M) and within the last week (6M). Ten women will continue their omnivorous diet throughout the entire study (controls) and the other 30 subjects will switch to a lacto-ovo-vegetarian diet for 6 months. The vegetarian group will be split in 2 groups, matched for age, weight, height and baseline carnosine concentrations in soleus and gastrocnemius medialis muscles. Fifteen of them will be supplemented with beta-alanine and creatine (Veg+Suppl) and the other 15 women will receive a placebo (Veg+Pla). A co-worker, not involved in the study design and analysis, will perform the randomisation and will prepare the containers with supplements. With regard to supplementation, the study is double-blind placebo-controlled. The lacto-ovo-vegetarian diet consists of vegetables, fruits, seeds, grains, meat substitutes, eggs and dairy products and the exclusion of meat, poultry and fish. Subjects will complete a 3 day food diary at the start and after 3 months and will receive nutritional advice by a dietician during the study to prevent deficiencies in macronutrients and micronutrients. Furthermore, vegetarian recipes will be provided by email to support the subjects in their vegetarian diet.

The supplementation protocol includes simultaneously daily oral administration of creatine monohydrate (Creapure®, AlzChem AG, Germany) and slow-release beta-alanine (Carnosyn®, Natural Alternatives International, San Marcos, USA) or a placebo (maltodextrin, Natural spices, France). The supplements are considered as safe and efficacious. The Veg+Suppl group ingests 1 g of creatine monohydrate (2 capsules of 500 mg) and 0.8 g of beta-alanine (1 Carnosyn® tablet) each day during the intervention period. The Veg+Pla group will be supplemented with an identical number of capsules and tablets of maltodextrin. All subjects are asked not to take any other supplements than those provided by the current study. Compliance will be checked by asking the subjects to return the containers and counting the pills that are left. The control group, who will remain on an omnivorous diet, will not receive any supplements.

Before (0M), after 3 (3M) and 6 months (6M), subjects will perform an incremental cycling test, a fasted venous blood sample and 24hr urine will be collected, a muscle biopsy of the vastus lateralis muscle will be taken and muscle carnosine content will be determined by 1H-MRS.

A two-way analysis of variance (ANOVA) will be used to evaluate plasma and urinary metabolite concentrations, muscle carnosine, muscle biopsy metabolite concentrations, time to exhaustion (TTE) and VO2max with 'group' (Veg+Suppl; Veg+Pla; control) as between-subject factor and 'time' (0M; 3M; 6M) as within-subject factor (SPSS statistical software, SPSS Inc, Chicago, USA). For the analysis of capillary lactate and pH, measurements before and after the incremental cycling test were included as another within factor (start; end). In case of significance, analyses were repeated for each group separately and pairwise comparisons were used to compare the different time points. Values will be presented as mean ± SD and statistical significance threshold will be set at p ≤0.05.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 40
• Est. completion date: June 2013
• Est. primary completion date: June 2013
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: Female
• Age group: 18 Years and older

Eligibility

Inclusion Criteria:

• women

Exclusion Criteria:

• smoking, chronic use of medication or taking supplements, athletes participating in competitions, vegetarianism or eating meat or fish less than 5 times a week

Related Conditions & MeSH terms

• Dietary Modification

Intervention

Behavioral:
• Vegetarian diet

Dietary Supplement:
• creatine
1g creatine/day
• Placebo
pills
• Beta-alanine
0.8g beta-alanine per day

Locations

Country	Name	City	State
n/a

Sponsors (1)

Lead Sponsor	Collaborator
University Ghent

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Fasted Plasma Beta-alanine Concentration	Fasted venous plasma beta-alanine concentration (precursor for carnosine) at 0, 3 and 6 months of the intervention	6 months
Primary	Gastrocnemius Carnosine Concentration	Gastrocnemius carnosine concentration at 0, 3 and 6 months of the intervention	6 months
Primary	Soleus Carnosine Concentration	Soleus carnosine concentration at 0, 3 and 6 months of the intervention	6 months
Primary	Plasma Creatine Concentration	Plasma creatine concentration at 0, 3 and 6 months of the intervention	6 months
Primary	Plasma Creatinine Concentration	Plasma creatinine at 0, 3 and 6 months of the intervention	6 months
Primary	Plasma Guanidinoacetate Concentration	Plasma guanidinoacetate at 0, 3 and 6 months of the intervention	6 months
Primary	Urinary Creatinine Concentration	Urinary creatinine at 0, 3 and 6 months of the intervention	6 months
Primary	Muscle Creatine Concentration	Muscle total creatine concentration in vastus lateralis muscle at 0 and 3 months of the intervention	3 months
Primary	Plasma Carnitine Concentration	plasma free carnitine concentration at 0, 3 and 6 months of the intervention	6 months
Primary	Plasma Acetylcarnitine Concentration	plasma acetylcarnitine concentration at 0, 3 and 6 months of the intervention	6 months
Primary	Plasma Total Carnitine Concentration	plasma total carnitine concentration (free + acetyl) at 0, 3 and 6 months of the intervention	6 months
Primary	Muscle Carnitine Concentration	muscle free carnitine concentration in vastus lateralis muscle at 0 and 3 months of the intervention	3 months
Primary	Muscle Acetylcarnitine Concentration	muscle acetylcarnitine concentration in vastus lateralis muscle at 0 and 3 months of the intervention	3 months
Primary	Muscle Total Carnitine Concentration	muscle total carnitine concentration (free + acetylcarnitine) in vastus lateralis muscle at 0 and 3 months of the intervention	3 months
Secondary	Vitamin D Status	Serum 25-Hydroxyvitamin D concentration at 0, 3 and 6 months of the intervention	6 months
Secondary	Urinary Biomarker for Meat Intake: Pi-methyl-histidine	urinary pi-methyl-histidine concentration at 0, 3 and 6 months of the intervention	6 months
Secondary	Urinary Biomarker for Meat Intake: Tau-methyl-histidine	urinary tau-methyl-histidine concentration at 0, 3 and 6 months of the intervention	6 months
Secondary	Urinary Biomarker for Meat Intake: Anserine	urinary anserine concentration at 0, 3 and 6 months of the intervention	6 months
Secondary	VO2max	VO2max during incremental cycling test performed at 0, 3 and 6 months	6 months
Secondary	Time to Exhaustion	Time to exhaustion during incremental cycling test performed at 0, 3 and 6 months	6 months
Secondary	Capillary Lactate	capillary lactate at the start and at the end of the incremental cycling test performed at 0, 3 and 6 months	6 months
Secondary	Capillary pH	capillary pH at the start and at the end of the incremental cycling test performed at 0, 3 and 6 months	6 months