Determinants of serum 25(OH)D concentration in young and middle-aged adults. The Cardiovascular Risk in Young Finns Study

Figures & data

Table I. Characteristics of the study population.

	Men^a Mean ± SD^b	Women^a Mean ± SD^b
Age (years)	37.6 ± 5.1	37.7 ± 5.0
BMI (kg/m²)	26.7 ± 4.2	25.4 ± 5.1
Waist (cm)	94.4 ± 11.9	83.7 ± 12.8
Dietary vitamin D intake (μg/d)	9.0 ± 3.9	6.8 ± 2.9
Vitamin D density (μg/MJ/d)	0.81 ± 0.30	0.75 ± 0.25
Nutrient supplement use (%)^c	38.2	50.0
Milk (g/d)	474.0 ± 374.4	331.8 ± 278.4
Sour milk products (g/d)	143.5 ± 167.3	180.0 ± 183.7
Fish (g/d)	33.6 ± 24.3	25.9 ± 18.6
Fish products (g/d)	11.8 ± 15.0	7.7 ± 8.4
Margarine (g/d)	13.2 ± 12.1	10.9 ± 9.2
Eggs (g/d)	27.5 ± 22.3	22.2 ± 17.8
Alcohol consumption (drinks/day)	1.4 ± 1.8	0.6 ± 0.7
Smoking (%)^d	22.6	14.9
Health habits (ordinal)^e	3.3 ± 1.0	3.7 ± 0.9
Sunny holiday (%)^f	24.4	26.5
Sun avoidance (%)^g	38.2	50.3
Skiing holiday (%)^h	17.9	16.4
Physical activity (MET hours/week)	19.7 ± 21.9	19.7 ± 20.7
Educational status (from 1 to 3)	2.2 ± 0.5	2.2 ± 0.5
1. Comprehensive school (%)	6.2	3.9
2. High school or vocational school (%)	71.6	69.5
3. Academic degree (%)	22.2	26.6
Study center latitude
60°10’ N (Helsinki) (%)	29.0	28.8
60°27’ N (Turku) (%)	18.9	16.0
61°29’ N (Tampere) (%)	16.8	18.1
62°53’ N (Kuopio) (%)	21.3	24.1
65°01’ N (Oulu) (%)	14.1	12.9
Serum testosterone concentration (nmol/L)	16.35 ± 5.30
Oral contraceptives (%)		16.0
Pregnancy (%)^i		3.1
Given birth (%)^j		75.3
Lactating (%)		4.0

^aMen n = 994, and women n = 1,210.

^bMean and standard deviation unless stated otherwise.

^cRegular and irregular use of any kind of nutrient supplement.

^dDaily smokers.

^ePaying attention to health habits (1 = not at all; 5 = very much).

^fA holiday in a sunny place abroad during the previous year.

^gPrevalence of individuals trying to avoid sunlight exposure.

^hSkiing holiday during the previous year in thehome country or abroad.

ⁱPregnancy during the study visit.

^jIndividuals ever given birth.

Figure 1. Cumulative distribution of serum 25(OH)D concentration and cut-off points for serum vitamin D deficiency (men: 4.2%, women: 3.2%), hypovitaminosis D (men: 38.1%, women: 34.1%), and sufficient concentration (men: 12.7%, women 20.0%). (Men n = 994; women n = 1,210).

Table II. Univariate linear regression analyses on determinants of serum 25(OH)D concentration.

Univariate analysis	β ± SE	P value	P for sex interaction	n
Sex (male/female)	–4.20 ± 0.81	< 0.0001		2204
Age (years)	0.016 ± 0.081	0.84	0.0010	2204
BMI (kg/m²)	–0.78 ± 0.085	< 0.0001	0.16	2162
Waist (cm)	–0.31 ± 0.030	< 0.0001	0.16	2174
Dietary vitamin D intake (μg/d)	0.45 ± 0.12	0.0002	0.50	1966
Nutrient supplement use (no/yes)^a	7.22 ± 0.89	< 0.0001	0.83	1762
Milk (100 g/d)	0.55 ± 0.13	< 0.0001	0.64	1966
Sour milk products (100 g/d)	0.30 ± 0.25	0.22	0.87	1966
Fish (100 g/d)	6.35 ± 2.01	0.0016	0.34	1966
Margarine (10 g/d)	1.59 ± 0.41	0.0001	0.84	1966
Egg (10 g/d)	–0.37 ± 0.22	0.09	0.88	1966
Alcohol consumption (drinks/day)	–1.02 ± 0.29	0.0005	0.75	2168
Smoking (no/yes)^b	–6.38 ± 1.04	< 0.0001	0.063	2186
Health habits (ordinal)^c	3.72 ± 0.43	< 0.0001	0.79	2190
Sunny holiday (no/yes)^d	6.65 ± 1.03	< 0.0001	0.12	1763
Sun avoidance (no/yes)^e	2.60 ± 0.91	0.0044	0.17	1749
Skiing holiday (no/yes)^f	3.93 ± 1.20	0.0011	0.47	1758
Physical activity (MET hours/week)	0.11 ± 0.020	< 0.0001	0.56	2076
Educational status^g	2.70 ± 0.80	0.0008	0.12	2190
Investigation month^h	–2.31 ± 0.61	0.0002	0.41	2192
Study center latitude	–0.39 ± 0.25	0.12	0.20	2194
rs10741657^i	–1.18 ± 0.60	0.049	0.26	2203
rs12785878^i	1.68 ± 0.61	0.0057	0.48	2023
rs2282679^i	–5.78 ± 0.76	< 0.0001	0.20	2023
rs6013897^i	1.68 ± 0.70	0.016	0.99	2023

^aRegular and irregular use of any kind of nutrient supplement.

^bNon-smokers and irregular smokers in one group, daily smokers in the other.

^cNo interest in health = 1, major interest = 5.

^dA holiday in a sunny place abroad during the previous year.

^eIndividuals trying to avoid sunlight exposure.

^fSkiing holiday during the previous year in the home country or abroad.

^g1 = Comprehensive school, 2 = High school or vocational school, and 3 = Academic degree.

^hInvestigation months, October and February = 1, November and January = 2, December = 3, assumed linear decrease in sunlight amount.

ⁱSingle nucleotide polymorphisms rs10741657-CYP2R1, rs12785878-DHCR7, rs2282679-GC, and rs6013897-CYP24A1.

Table III. Multivariable analysis on determinants of serum 25(OH)D concentration. Both total model and individual variable R2 values are shown.

	Pooled^a			Men^a			Women ^a
Multivariable analysis—model 1	β ± SE	P value	R²	β ± SE	P value	R²	β ± SE	P value	R²
Model R-square			0.1849			0.1871			0.2353
Male (sex)	–3.17 ± 1.10	0.0040	0.0069
Age (years)	–0.039 ± 0.098	0.69	0.0001	0.28 ± 0.13	0.034	0.0080	–0.22 ± 0.15	0.14	0.0024
BMI (kg/m²)	–0.48 ± 0.11	< 0.0001	0.0146	–0.38 ± 0.17	0.027	0.0095	–0.55 ± 0.15	0.0002	0.0190
Dietary vitamin D intake (μg/d)	0.87 ± 0.15	< 0.0001	0.0144	0.77 ± 0.17	< 0.0001	0.0271	1.23 ± 0.24	< 0.0001	0.0251
Nutrient supplement use (no/yes)^b	5.33 ± 1.00	< 0.0001	0.0313	4.95 ± 1.41	0.0005	0.0298	5.91 ± 1.39	< 0.0001	0.0216
Alcohol consumption (drinks/day)	–0.60 ± 0.35	0.088	0.0016	–0.81 ± 0.34	0.018	0.0120	–0.073 ± 0.97	0.94	0.0000
Smoking (no/yes)^c	–3.97 ± 1.39	0.0043	0.0069	–2.10 ± 1.78	0.24	0.0015	–5.17 ± 2.11	0.014	0.0089
Health habits (ordinal)^d	1.48 ± 0.60	0.014	0.0181	0.92 ± 0.77	0.23	0.0047	2.12 ± 0.89	0.017	0.0288
Sunny holiday (no/yes)^e	6.06 ± 1.12	< 0.0001	0.0230	4.91 ± 1.59	0.0021	0.0166	6.47 ± 1.56	< 0.0001	0.0245
Sun avoidance (yes/no)^f	–3.59 ± 0.99	0.0003	0.0070	–2.94 ± 1.39	0.034	0.0062	–3.95 ± 1.40	0.0048	0.0090
Skiing holiday (no/yes)^g	2.88 ± 1.29	0.026	0.0030	2.52 ± 1.73	0.15	0.0023	3.07 ± 1.86	0.099	0.0031
Physical activity (MET hours/week)	0.026 ± 0.024	0.27	0.0007	0.027 ± 0.031	0.39	0.0009	0.035 ± 0.035	0.32	0.0012
Educational status^h	0.68 ± 1.04	0.51	0.0003	–1.17 ± 1.40	0.40	0.0010	2.01 ± 1.47	0.17	0.0020
Investigation month^i	–2.80 ± 0.70	< 0.0001	0.0099	–3.68 ± 0.97	0.0002	0.0174	–2.61 ± 0.99	0.0084	0.0068
Study center latitude	–0.24 ± 0.31	0.43	0.0004	–0.54 ± 0.42	0.20	0.0022	0.11 ± 0.43	0.81	0.0001
rs10741657^j	–0.78 ± 0.68	0.25	0.0007	–0.83 ± 0.92	0.37	0.0015	–0.86 ± 0.97	0.38	0.0009
rs12785878^j	–2.10 ± 1.01	0.0380	0.0024	–1.91 ± 1.42	0.18	0.0023	–2.11 ± 1.42	0.14	0.0025
rs2282679^j	–7.13 ± 0.89	< 0.0001	0.0360	–6.48 ± 1.21	< 0.0001	0.0344	–7.71 ± 1.25	< 0.0001	0.0354
rs6013897^j	–2.81 ± 0.78	0.0004	0.0076	–2.38 ± 1.106	0.032	0.0085	–2.96 ± 1.09	0.0067	0.0084
Testosterone (nmol/L)				0.13 ± 0.14	0.36	0.0012
Oral contraceptives							11.14 ± 1.86	< 0.0001	0.0337
Pregnancy (no/yes)^k							2.32 ± 5.12	0.65	0.0003
Given birth (no/yes)^l							2.71 ± 1.72	0.12	0.0016
Lactating (no/yes)							–0.82 ± 3.94	0.84	0.0000

^aMen n = 565, women n = 742, and pooled n = 1,322.

^bRegular and irregular use of any kind of nutrient supplement.

^cDaily smokers.

^dPaying attention to health habits (1 = not at all; 5 = very much).

^eA holiday in a sunny place abroad during the previous year.

^fPrevalence of individuals trying to avoid sunlight exposure.

^gSkiing holiday during the previous year in the home country or abroad.

^h1 = Comprehensive school, 2 = High school or vocational school, and 3 = Academic degree.

ⁱInvestigation months, October and February = 1, November and January = 2, December = 3, assumed linear decrease in sunlight amount.

^jSingle nucleotide polymorphisms rs10741657-CYP2R1, rs12785878-DHCR7, rs2282679-GC, and rs6013897-CYP24A1.

^kPregnancy during the study visit.

^lIndividuals ever given birth.

Table IV. Logistic regression analyses on determinants of hypovitaminosis D.

	Pooled^a		Men^a		Women^a
	OR	CI 95%	OR	CI 95%	OR	CI 95%
Male (sex)	1.05	0.79–1.40
Age (years)	0.99	0.97–1.02	0.97	0.93–1.01	1.02	0.98–1.06
BMI (kg/m²)	1.06	1.03–1.09	1.04	0.99–1.10	1.08	1.04–1.12
Dietary vitamin D intake (μg/d)	0.90	0.86–0.93	0.92	0.88–0.98	0.86	0.81–0.92
Nutrient supplement use (no/yes)^b	0.66	0.51–0.85	0.53	0.35–0.80	0.71	0.49–1.01
Alcohol consumption (drinks/day)	1.18	1.07–1.30	1.16	1.04–1.30	1.26	1.00–1.60
Smoking (no/yes)^c	1.36	0.97–1.92	1.13	0.68–1.85	1.39	0.84–2.29
Health habits (ordinal)^d	0.87	0.75–1.01	0.91	0.73–1.13	0.83	0.66–1.03
Sunny holiday (yes/no)^e	0.55	0.41–0.75	0.59	0.37–0.94	0.48	0.31–0.74
Sun avoidance (no/yes)^f	1.20	0.93–1.55	1.22	0.82–1.81	1.24	0.86–1.77
Skiing holiday (yes/no)^g	0.73	0.51–1.04	0.91	0.55–1.50	0.59	0.35–0.99
Physical activity (MET hours /week)	1.00	0.99–1.00	0.99	0.98–1.00	1.00	0.99–1.01
Educational status^h	1.06	0.81–1.38	1.12	0.75–1.67	1.05	0.72–1.53
Investigation month^i	1.35	1.12–1.61	1.50	1.38–1.97	1.27	0.98–1.63
Study center latitude	0.99	0.91–1.08	0.98	0.87–1.11	0.98	0.88–1.10
rs10741657^j	1.13	0.95–1.35	1.15	0.88–1.50	1.18	0.92–1.52
rs12785878^j	1.31	1.00–1.70	1.59	1.05–2.40	1.08	0.75–1.55
rs2282679^j	2.08	1.66–2.60	2.02	1.43–2.85	2.15	1.57–2.94
rs6013897^j	1.12	0.91–1.36	1.00	0.73–1.38	1.24	0.95–1.63
Testosterone (nmol/L)			1.02	0.98–1.06
Oral contraceptives (no/yes)					0.45	0.27–0.75
Given birth (no/yes)^k					0.55	0.35–0.84
Lactating (no/yes)					0.50	0.14–1.86

Pregnancy was left out from the model due to the lack of pregnant women with hypovitaminosis D and observations of all covariables.

^aMen n = 565, women n = 743, and pooled n = 1,322.

^bRegular and irregular use of any kind of nutrient supplement.

^cDaily smokers.

^dPaying attention to health habits (1 = not at all; 5 = very much).

^eA holiday in a sunny place abroad during the previous year.

^fPrevalence of individuals trying to avoid sunlight exposure.

^gSkiing holiday during the previous year in the home country or abroad.

^h1 = Comprehensive school, 2 = High school or vocational school, and 3 = Academic degree.

ⁱInvestigation months, October and February = 1, November and January = 2, December = 3, assumed linear decrease in sunlight amount.

^jSingle nucleotide polymorphisms rs10741657-CYP2R1, rs12785878-DHCR7, rs2282679-GC, and rs6013897-CYP24A1.

^kIndividual ever given birth.

Figure 2. Distribution and cumulative distribution of dietary vitamin D intake by sex. (Men n = 869, women n = 1,097).

Figure 3. Achievement of the recommended minimum daily vitamin D intake in those with serum 25(OH)D concentration < 50 nmol/L. The two-sided P values of Fisher's exact test are reported. (Men n = 869; women n = 1,097).