Dietary supplement use in younger and older men exercising at gyms in Cape Town

Figures & data

Table 1: Sociodemographic information and use of medication for specified conditions

Characteristic	n	Younger	n	Older	p-value
Age (years) mean ± SD	210	25.0 ± 5.3	91	58.4 ± 8.3	< 0.001^1
Ethnicity (column %):	210		91		< 0.001^2
Black		12.7		1.1
White		57.1		91.2
Mixed ancestry		24.3		5.5
Indian		3.3		2.2
Other		2.4		0.0
Education (column %):	210		91		0.143^2
School		20.5		22.0
Degree/diploma		63.8		46.1
Postgraduate degree		15.2		29.7
Other		0.5		2.2
Medication (% yes):^3	143		46
Hypertension	2	1.4	9	29.6	< 0.001^2
Diabetes	0	0.0	3	6.5	0.002^2
Blood cholesterol	2	1.4	7	15.2	< 0.001^2

SD: Standard deviation.

¹Independant sample t-test.

²Pearson's chi-square test.

³Sub-sample of n = 189; balance reported no medication use.

Table 2: Perception of health, quality of diet, and knowledge of supplements

Variable (column %)	Younger (n = 210)	Older (n = 91)	p-value^1
Health:			0.243
Poor	1.0	2.2
Reasonable	17.6	23.1
Good	81.4	74.7
Quality of diet:			0.506
Poor	7.1	4.4
Reasonable	34.3	30.8
Good	58.6	64.8
Knowledge of supplements:			< 0.001
Poor	15.7	36.3
Reasonable	34.8	35.2
Good	49.5	28.5

¹Pearson's chi-square test.

Table 3: Gym exercise profile and main goal for exercising in a gym

Variable	n	Younger	n	Older	p-value
	210		91
Total number of years (mean ± SD)		4.1 ± 3.3		12.7 ± 12.9	< 0.001^1
Total hours/week (mean ± SD)		6.1 ± 4.0		4.0 ± 1.7	< 0.001^1
Strength exercise:
Yes (%)		89.1		80.2	0.040^2
Hours/week (mean ± SD)		4.0 ± 2.9		1.6 ± 1.2	< 0.001^1
Aerobic exercise:
Yes (%)		80.5		92.1	0.010^2
Hours/week (mean ± SD)		1.9 ± 1.9		2.1 ± 1.6	0.363^1
Aerobic classes:
Yes (%)		9.5		9.9	0.921^2
Hours/week (mean ± SD)		0.2 ± 1.0		0.2 ± 0.6	0.579^1
Flexibility classes:
Yes (%)		5.7		14.3	0.013^2
Hours/week (mean ± SD)		0.1 ± 0.6		0.2 ± 0.5	0.302^1
Main goal for exercising (column %):	206		89
Strength/muscles		38.8		7.8	< 0.001^3
Stay fit		21.8		41.6
Stay healthy		15.0		41.6
Look good		15.5		1.1
Lose weight		5.8		7.9
Other		3.1		0

SD: Standard deviation; n varies due to missing values.

¹Independant sample t-test.

²Pearson's chi-square test.

Table 4: Energy and protein supplement use

Supplement use (column %)	Younger (n = 210)	Older (n = 91)	p-value^1
Energy drinks:
Regularly	12.4	5.5	0.014
Occasionally	37.6	24.2
Never	50.0	70.3
Protein bars:
Regularly	3.8	0	0.038
Occasionally	14.3	7.7
Never	81.9	92.3
Protein powders:
Regularly	37.1	6.6	< 0.001
Occasionally	12.9	2.2
Never	50	91.2
Amino acids:
Regularly	11.9	1.1	0.004
Occasionally	3.3	1.1
Never	84.8	97.8
Weight gainers:
Regularly	8.8	0	0.011
Occasionally	2.4	1.1
Never	89.1	98.9
Recovery drinks:
Regularly	7.6	0	0.026
Occasionally	6.2	6.6
Never	86.2	93.4

¹Pearson's chi-square test.

Table 5: Ergogenic aid use

Supplement use (column %)	Younger (n = 210)	Older (n = 91)	p-value^1
Creatine:
Regularly	21.4	1.1	< 0.001
Occasionally	12.9	3.3
Never	65.7	95.6
Glutamine:
Regularly	14.8	2.2	0.004
Occasionally	7.6	5.5
Never	77.6	92.3
Arginine:
Regularly	5.2	0	0.016
Occasionally	3.3	0
Never	91.4	100
Pre-train:
Regularly	7.1	3.3	0.04
Occasionally	4.8	0
Never	88.1	96.7
Fat burner:
Regularly	6.2	0	0.004
Occasionally	5.2	0
Never	88.6	100
Glucosamine:
Regularly	0.5	8.8	< 0.001
Occasionally	0.5	2.2
Never	99.1	89

¹Pearson's chi-square test.

Table 6: Main reason for use, source of information and perception of effectiveness of products in the three supplement groups (column %)

	MAIO supplements			Energy and protein supplements			Ergogenic aids
	Younger	Older	p-value^1	Younger	Older	p-value	Younger	Older	p-value^1
Main reason for use:	n = 124	n = 67		n = 117	n = 44		n = 108	n = 24
General health	71.8	80.6	0.034	22.2	18.2	0.218	17.6	20.8	< 0.001
Sport performance	18.7	11.9		58.5	47.7		63.9	25.0
Reduce body fat	0	3		4.1	6.8		8.3	0
Increase energy	8.9	1.5		15.2	27.3		10.2	4.2
Protect joints	0.8	3		0	0		0	50.0
Source of information:	n = 134	n = 69		n = 176	n = 71		n = 161	n = 47
Trainer/other gym users	24.6	13.0	0.001	17.6	7.0	< 0.001	32.3	25.5	0.002
Representative/pharmacist	12.7	7.3		22.7	9.9		12.6	2.1
Dietitian/nutritionist	9.7	13.0		8.5	14.1		9.6	6.4
Doctor	18.7	20.3		18.2	22.5		6.6	12.8
Family/friends	15.6	17.4		18.8	18.3		12.6	17.0
Magazines/TV	3	20.3		2.3	19.7		7.7	27.7
Internet	15.7	8.7		11.9	8.5		18.6	8.5
Effectiveness:	n = 133	n = 69		n = 171	n = 44		n = 107	n = 24
Somewhat	8.2	15.9	0.034	5.2	15.9	0.005	2.8	16.7	0.003
Moderate	27.1	37.7		23.4	36.4		17.8	33.3
Effective	64.7	46.4		71.4	47.7		79.4	50.0

MAIO = micronutrient-, anti-oxidant- and immune- or other health-boosting.

¹Pearson's chi-square test.