Efficacy of L-carnitine supplementation on frailty status and its biomarkers, nutritional status, and physical and cognitive function among prefrail older adults: a double-blind, randomized, placebo-controlled clinical trial

Figures & data

Figure 1 Subjects’ recruitment flowchart.

Table 1 Sociodemographic characteristics of the L-carnitine and placebo groups

Parameter	L-carnitine group (n=26)	Placebo group (n=24)	P-value
Mean age (years)	68.2±6.3	68.8±6.5	0.742a
Sex
Male	14 (53.8%)	9 (37.5%)	0.191b
Female	12 (46.2%)	15 (62.5%)
Race
Malay	20 (76.9%)	19 (79.2%)	0.656b
Chinese	2 (7.7%)	2 (8.3%)
Indian	4 (15.4%)	3 (8.3%)
Marital status
Married	21 (80.8%)	17 (70.8%)	0.313b
Not married	5 (19.2%)	7 (29.2%)
Living status
Living alone	2 (7.7%)	1(4.2%)	0.534b
Living with company	24 (92.3%)	23 (95.8%)
Level of education
Mean schooling period (years)	10±3	10±3	1a
Employment status
Working	3 (12%)	1 (4.2%)	0.324b
Not working	22 (88%)	23 (95.8%)

Notes:

a Mann–Whitney test,

b chi-square test.

Table 2 Effects of the intervention on the primary outcome variables for the L-carnitine and placebo groups (presented as mean ± SD)

Parameters	L-carnitine group (mean ± SD)	P-value	Placebo group (mean ± SD)	P-value
Frailty lndex score
Baseline	0.112±0.065	0.001a	0.118±0.045	0.764a
5 weeks	0.097±0.063		0.116±0.056
10 weeks	0.076±0.0578		0.111±0.062
Hand grip (kg)
Baseline	23.6±6.9	0.012a	22.8±6.5	0.058a
5 weeks	23.6±7.3		21.2±6.7
10 weeks	24.4±7.4		21.7±5.4
2-minute step test (step)
Baseline	69±22	0.350a	93±31	0.828a
5 weeks	72±27		83±32
10 weeks	76±23		85±23
Time up and go (s)
Baseline	12.2±8.5	0.231a	9.5±2.6	0.097a
5 weeks	9.2±2.9		8.9±3.1
10 weeks	9.4±1.9		9.5±2.9
Usual pace (s)
Baseline	6.5±1.2	0.234a	6.6±1.6	0.106a
5 weeks	6.2±1.5		6.5±1.4
10 weeks	6.4±1.0		6.9±1.6
Rapid pace (s)
Baseline	4.9±0.7	0.509a	5.1±1.3	0.397a
5 weeks	5.1±1.3		5.0±1.5
10 weeks	4.9±0.9		5.2±1.3
Shoulder strength (kg)
Baseline	11.7±5.7	0.022a	11.3±5.2	0.009**,a
5 weeks	11.9±5.6		11.4±4.9
10 weeks	13.8±5.9		13.5±4.7
Peak expiratory flow rate (L/min)
Baseline	400±100	0.241a	380±100	0.675a
5 weeks	415±90		390±80
10 weeks	410±80		380±90
Chair stand test (times/30 s)
Baseline	11.0±3.3	0.07a	11.3±3.6	0.05a
5 weeks	11.5±3.8		12.1±3.69
10 weeks	11.3±3.8		11.1±4
Physical activity scale PASE
Baseline	155±60	0.025a	150±70	0.013*,a
5 weeks	120±40		110±40
10 weeks	150±50		130±30
Activity of daily living
Baseline	6±0	NA	6±0	NA
5 weeks	6±0		6±0
10 weeks	6±0		6±0
Instrumental activity of daily living
Baseline	13.9±0.4	0.765a	13.6±0.9	NA
5 weeks	13.9±0.4		13.6±0.9
10 weeks	13.9±0.5		13.6±0.9
Frailty biomarkers
Interleukin-6 (pg/mL)
Baseline	6.1±2.9	0.699b	6.2±2.3	0.05b
10 weeks	5.9±7.3		8.9±8.2
Tumor necrosis factor-α (pg/mL)
Baseline	5.9±2.0	0.802b	6.2±2.1	0.670b
10 weeks	5.9±4.9		5.8±3.9
Insulin-like growth factor-1 (ng/mL)
Baseline	92.7±37.8	0.585b	102.2±47.5	0.898b
10 weeks	103.9±65		99.7±65.3
Total L-carnitine (μmol/L)
Baseline	36.1±14.3	0.606b	35.6±14.8	0.130b
10 weeks	38.8±18.1		37±20.6
Free L-carnitine (μmol/L)
Baseline	32.4±12.4	0.845b	26.9±11.6	0.516b
10 weeks	33.9±5.1		31.1±3.3
Acyl L-carnitine (μmol/L)
Baseline	3.6±14.9	0.905b	8.6±15.2	0.819b
10 weeks	3.1±20.4		7.6±17.8

Notes:

* P<0.05,

** P<0.01,

a using Friedman test,

b using Wilcoxon test.

Abbreviations: PASE, Physical Activity Scale for Elderly; SD, standard deviation; NA, not applicable.

Figure 2 Percent change in Frailty Index score and physical function.

Notes: (A) Frailty Index, (B) Hand grip, (C) PEFR *P<0.05, **P<0.01, using independent t-test/Mann–Whitney test.
Abbreviation: PEFR, peak expiratory flow rate.

Figure 3 Percent of mean change in frailty in selected biomarkers.

Notes: (A) IL-6, (B) TNF-α, (C) IGF-1, no significant differences were found using independent t-test/Mann–Whitney test.
Abbreviations: IL-6, interleukin 6; IGF-1, insulin-like growth factor-1; TNF-α, tumor necrosis factor-alpha.

Figure 4 Changes in the frailty scores according to Fried criteria.

Notes: (A) L-carnitine group, (B) Placebo group.

Figure 5 Changes in the frailty deficit percentage before and after the intervention.

Notes: (A) L-carnitine group, (B) placebo group.

Table 3 Self-reported side effect by subjects (presented as n [%])

Side effect	L-carnitine group (%)	Placebo group (%)	P-value
General feeling
Normal	19 (73.1)	17 (70.8)	0.554
Better	7 (26.9)	7 (29.2)
Worse	0 (0)	0 (0)
Feeling more energetic
Yes	11 (42.3)	4 (16.7)	0.047*
No	15 (57.7)	20 (83.3)
Nausea
Yes	0 (0)	0 (0)	0.674
No	26 (100)	24 (100)
Vomiting
Yes	0 (0)	0 (0)	0.603
No	26 (100)	24 (100)
Diarrhea
Yes	0 (0)	0 (0)	0.456
No	26 (100)	24 (100)
Constipation
Yes	1 (3.8)	0 (0)	0.476
No	25 (96.2)	24 (100)
Muscle pain
Yes	0 (0)	1 (4.2)	0.334
No	26 (100)	23 (95.8)
Appetite
Increased	2 (7.7)	0 (0)	0.443
Same	23 (88.5)	20 (83.3)
Decrease	1 (3.8)	4 (16.7)
Sleep
More	0 (0)	1 (4.2)	0.443
Same	26 (100)	23 (95.8)
Less	0 (0)	0 (0)

Note:

* P<0.05 using chi-square test.