To find the relation between vitamin D level and depression, the vitamin D levels of 100 healthy subjects and 100 depressed subjects were determined, as shown in Table 1. They were divided into three groups according to their age, i.e., Group-I comprised subjects below 20 years and below 20 years, Group-II included subjects between 21 and 60 years, and Group-III comprised of subjects above 61 years and above 61 years, and observation has been recorded, respectively.

Table 1 Comparative vitamin D level of total normal (100) and total depressed (100) subjects determined in nanogram per milliliter (ng/mL) given as mean ± SEMVitamin D profile of 100 normal subjects (males and females)

Table 2 shows the age and vitamin D data obtained for 100 normal male and female subjects. The mean ± SEM of the age of the normal male of 59 subjects was 39.28 ± 2.27 and the coefficient of variation (CV) of age was found as 44.42%. While the mean ± SEM of vitamin D level was found as 34.65 ± 3.84 and 84.84% CV.

Table 2 Age vitamin D level of normal male (59) and female (41) subjects determined in nanogram per milliliter (ng/mL) given as mean ± SEM

Similarly, the age and vitamin D data of all normal female 41 subjects revealed that the mean ± SEM of age is 45.82 ± 2.3 with 31.79% CV, while 61.45 ± 7.16 was the mean ± SEM of vitamin D level and CV was observed 74.62%. The p value of age (p < 0.05) and p value of vitamin D (p < 0.05) are given.

Age, vitamin D and depression profile of 100 subjects with depression (male and female)

Table 3 shows the age, vitamin D, and depression profile of 41 male subjects with depression. The data given in the table indicated the mean ± SEM of age is 38.87 ± 2.089, and 34.41% is the CV. The mean ± SEM of vitamin D level given is 24.17 ± 1.32 with a 34.96% CV. The mean ± SEM of depression level on the BDI scale given in the table is 25.8 ± 1.49 with a 37.17% CV.

Table 3 Age vitamin D level and BDI score of the male (41) and female (59) patients determined in nanogram per milliliter (ng/mL) given as the mean ± SEM

Table 3 presents the age, vitamin D, and depression profile of all 59 female subjects with depression. The data obtained demonstrated the mean ± SEM of age as 45.5 ± 1.87 and 31.56% CV. The mean ± SEM of vitamin D level given is 23.36 ± 1.81 and 59.76% CV. The mean ± SEM of depression given is 28.06 ± 0.95, and 25.86% is the CV. The p value of age (p < 0.05) and p value of vitamin D was (p > 0.05) are given. The p value of age is significant, while that vitamin D is non-significant.

Depression and vitamin D profile of subjects of 20 years and below (Group-I)

In Group-I (Table 4), subjects of 20 years and below comprising of 10 normal and 4 subjects with depression were evaluated for their vitamin D and depression level. For the 10 normal subjects, the mean ± SEM of age found was 15.9 ± 0.6 with a 12.01% CV. For vitamin D level, the mean ± SEM was calculated as 17.67 ± 0.56, and the CV was found as 9.91%.

Table 4 Age vitamin D level of normal and depressed along with BDI score of subjects 20 years of age and below of (Group I) given as the mean ± SEM

The depression and vitamin D profile of the 4 depressed subjects (Table 4) of this group showed mean ± SEM of vitamin D level as 23.2 ± 1.06, and 9.14% was recorded as the CV. The mean ± SEM of BDI score was calculated as 19 ± 3.1, and of age was calculated as17.75 ± 1.43. The p value of age (p > 0.05) and p value of vitamin D (p > 0.05) are non-significant.

Depression and vitamin D profile of subjects between 21 and 60 years (Group-II)

Table 5 discusses the statistics of all the 70 normal subjects. The mean ± SEM of the age of 40 normal subjects determined was 39.18 ± 5.83 with a 14.9% CV. The mean ± SEM of vitamin D level of the 40 normal subjects was calculated as 44.51 ± 4.21 ng/mL, and the CV was 79.16%.

Table 5 Age vitamin D level of normal and depressed subjects of age 21 to 60 years of both sexes belonging to (Group II) given as the mean ± SEM

For the group of age 21–60 years, the mean ± SEM of ages of all 80 subjects with depression were statistically determined as 39.35 ± 1.09, and the CV was calculated as 24.85%. The mean ± SEM of vitamin D level of all subjects was statistically calculated as 24.1 ± 1.44 ng/mL. The CV was determined as 32.1%, respectively, while 26.78 ± 0.96 as the mean ± SEM of depression (Table 5). The p value of age (p > 0.05) is non-significant and p value of vitamin D (p < 0.05) is significant.

Among all the depressed subjects, the vitamin D levels of 16 subjects (20%) were found normal, while vitamin D of 40 subjects (50%) was mildly deficient, and 24 subjects (30%) with depression were severely deficient in vitamin D level.

The relations between vitamin D and depression level in subjects with depression of age group 21 to 60 years of age have been summarized in Table 5. A total of 80 subjects were selected which were declared as depressed after examining them on the BDI scale.

All subjects with depression were scrutinized thoroughly on BDI scales to find their level of depression. It was found that 23 (28.7%) of them were mildly depressed, 19 subjects (23.7%) with moderate depressed and 38 subjects (47.5%) were found severely depressed. The moderate depressed 19 subjects (23.7%) were also examined for their vitamin D level, and significant results were found, 6 subjects (31.57%) had a severe deficiency of vitamin D, 10 subjects (52.6%) were found with mild deficiency, and only 3 subjects (15.7%) were having normal levels of vitamin D.

The other 38 subjects (47.5%) who were found as severely depressed on the BDI scale were also examined for their vitamin D level showed that 15 subjects (39.4%) had a severe deficiency of vitamin D, 16 subjects (42.1%) were found with moderate deficiency, and only 7 subjects (18.4%) had normal levels of vitamin D. In this age group an interesting relation between vitamin D and depression was noticed in the subjects. The results indicated the decrease in vitamin D levels was observed with increasing severity of depression calculated by the BDI scale.

The cumulative correlation between vitamin D and depression levels of all the mild, moderate, and severely depressed subjects, vitamin D levels of 20 subjects (25%) were found normal. A total of 28 subjects (35%) among the patients with depression showed a mild vitamin D deficiency, and 32 subjects (40%) with depression showed severe deficiency in their vitamin D levels. Moreover, the mean vitamin D of all the subjects with depression was found to be 24.1 ± 1.44 ng/mL, which is at the lower limit of mild deficiency and close to the upper margin of severe deficiency of vitamin D level with 53.48% CV.

Statistical analysis of BDI score of depression showed mean ± SEM, BDI score was 26.78 ± 0.96, which is the upper limit of moderate depression and approaching the least limits of severe depression. A 30.02% variation was recorded from the upper limit of the moderate depression showing 70% depression in the depressed subjects as at the upper level of moderate depression (Table 5).

The work was further continued to determine the relationship between the vitamin D level of normal and subjects with depression of age 21–60 years (Table 5). In the normal subjects, the mean ± SEM of vitamin D level was found to be 44.51 ± 4.21 ng/mL, and CV calculated was, respectively. While the mean of vitamin D level of subjects with depression was 23.15 ng/mL, considered as the mild deficiency of vitamin D. The CV of this level was calculated was 43.23% showed greater variation (Table 5).

Depression and vitamin D profile of 61 years and above subjects (Group III)

In the 3rd group, 20 healthy and 16 subjects with depression of 60 years and above were selected (Table 6). For the 20 healthy subjects, mean ± SEM of age was found as 65.65 ± 1.06, while the mean ± SEM of vitamin D calculated was 64.09 ± 11.96 and 7.2% and 83.5% was found as a CV in age and vitamin D level, respectively (Table 6).

Table 6 Age vitamin D level of normal and depressed subjects of 61 years of age and above belonging to (Group III) given as the Mean ± SEM

All the 16 subjects with depression were analyzed on the BDI scale in which 4 subjects were found with moderate depression, and twelve were having severely depression. Among the subjects with moderate depression, a vitamin D level of 1 was severe deficient, two were mildly deficient, and a vitamin D level of 1 was found normal (35.0 ng/mL). In the remaining 12 subjects with severe depression, the vitamin D level of 8 subjects was found to be mildly deficient, and three were severely deficient. While one subject showed a normal level of vitamin D. Here, an important correlation was observed between vitamin D levels and depression.

Statistical analysis of subjects shows the mean ± SEM of age 66.25 ± 1.2, while the mean ± SEM of vitamin D level was 21.8 ± 1.7in subjects having depression of age 60 and above. This value is very close to the severe deficiency of vitamin D level. On the other hand, on the BDI scale, 75% of the patients were with severe depression.

Furthermore, the mean ± SEM of BDI score was found to be 30.94 with a ± 5.14 standard deviation, which is the lower margin of severe depression. It is to be noted here that 13.4% variations from the mean vitamin D level suggest a more significant deficiency of vitamin D in subjects with depression in this case. Similarly, 16.6% variation from the mean BDI score was observed, which showed a strong correlation between vitamin D and depression.

Table 6, showing p value of age (p > 0.05) and p value of vitamin D (p < 0.05), p value of age is non-significant, while vitamin D is significant. Table 7 shows the vitamin D profile of all 100 normal subjects in which 59 (59%) subjects were male, and 41 (41%) female subjects irrespective of their age. Out of 100 normal subjects, 38 (38%) had normal vitamin D levels, of which 23 (60.5%) were female and 15 (39.5%) were male subjects. While 36 (36%) subjects had mild vitamin D levels, in which 6 (16.7%) were female, and 30 (83.3%) were male subjects. In Table 6 (17%), subjects had severe vitamin D deficiency, in which 6 (35.3%) were female, and 11 (64.7%) were male subjects. In all total 100 subjects, 9 (9%) showed a toxic level of vitamin D, of which 6 (66.7%) were female, and 3 (33.3%) were male.

Table 7 Vitamin D level of normal, depressed and depression status of depressed subjects has been mentioned as the mean ± SEM

Table 7 shows the vitamin D profile of all 100 subjects with depression, of which 59 (59%) subjects were female and 41 (41%) male subjects irrespective of their age. In all 100 subjects, 19 (19%) showed normal vitamin D levels, of which 12 (63.2%) were female, and 7 (36.8%) were male subjects. While 51 (51%) showed a mild deficiency of vitamin D level, in which 24 (47.1%) were female, and 27 (52.9%) were male subjects. In the same table 30 (30%) subjects were having severe vitamin D deficiency, in which 23 (76.7%) were female, and 7 (23.3%) were male subjects.

The depression profile of all 100 subjects with depression irrespective of their age. Table 7 indicates that out of 100 subjects, 26 (26%) were having mild depression, of these 26 subjects were having mild depression 10 (38.5%) were female, and 16 (61.5%) were male subjects. While 24 (24%) subjects were having moderate depression, in which 16 (66.7%) subjects were female, and 8 (33.3%) were male. In the same table, 50 (50%) subjects were having severe depression, in which 33 (66%) subjects were female, and 17 (34%) were male.