Adaptation status of military personnel in the Arctic under nutritional optimization with a food product containing biologically active substances

INTRODUCTION

State interests in the development of the Arctic zone of Russia necessitate a permanent military presence as part of the strategic deterrent forces^1,2. Under changing living conditions, significant alterations occur in the functional state of the human body, with physiological functions being reorganized to a new adaptive level [1]. Even permanent residence in the Far North among indigenous small-numbered peoples is associated with stress on the body’s adaptive mechanisms responsible for homeostasis maintenance [2][3]. It, therefore, can be expected that prolonged deployment of healthy military personnel in this area, in the course of their professional activity, may have a negative impact on the body’s adaptation status and overall resistance [4].

Human activities in northern environments lead to an increase in the body’s energy and plastic requirements, including vitamins and minerals³. In this context, the adequate nutrition of military personnel based on a scientifically ground system that ensures the intake of essential nutrients, including micronutrients, plays an important role in the acclimatization of servicemen, preserving their health and preventing chronic adaptive stress.

The conducted analysis of combined-arms and naval rations showed a reduced content of vitamins A, C, B₁, B₂, and niacin, as well as a calcium deficiency [5][6]. The study by Kirichenko et al. emphasized the regular (course-based) introduction of vitamins and minerals into the diet of military personnel during autumn–winter periods [7]. A number of studies [8–11] proposed food products possessing therapeutic and prophylactic properties, the formulations of which were developed based on local raw materials, both plant- (northern berries) and protein-based (from animal husbandry and fishing). For example, the development of food products aimed at enhancing the body’s adaptive capacity takes into account the pathogenesis of the predominant diseases observed among populations residing in northern regions [9]. At the same time, the technological and resource constrains associated with the production of such products from raw materials and berries limit their widespread application [8–11]. Consequently, the creation of food products that contribute to the prevention of diseases associated with the specific conditions of professional activity in the North remains a pressing issue.

The aim of this study was to assess the adaptation status of military personnel in the Arctic following the inclusion of a natural food product containing dietary and biologically active substances in the diet.

MATERIALS AND METHODS

The study, conducted in June–July 2022 in the Arctic, involved healthy and practically healthy male contract military personnel (n = 60; mean age 37.3 ± 3.1 years). The median duration of professional activity of the participants was 7.0 [ 5; 9] years.

In order to assess the effectiveness of the tested plant protein product (PPP) on their adaptation state, the subjects were divided into the following groups:

• Group 1 (main, n= 30) received 10.0 g of the PPP as part of the main course during dinner for 21 days;
• Group 2 (comparison, n= 30) received a standard ration.

The inclusion criteria were healthy and practically healthy military personnel who provided their voluntarily consent to participate in the study, who had not taken vitamin and mineral complexes or dietary supplements, and who had not traveled on leave to other regions of the country over the previous six months.

The basic food ration included products delivered during the navigation period, such as canned vegetables, vegetables and fruits heat-dried according to norm No. 1, as well as products delivered to regions of the Far North⁴. Water supply was provided using melted snow or ice, characterized by low mineralization. The living and working conditions of the participants were identical. Prior to the onset of the study, no vitamin or specialized food products were included in the diet.

Based on the results of previous studies assessing hemogram parameters in military personnel [12][13], as well as data on insufficient iodine supply in the human body under northern conditions [14][15], a formulation of PPP was developed. The product includes the following ingredients: chokeberry, flax seeds, carrots, broccoli, kelp (seaweed), and chicken egg shell. The primary processing method for the ingredients was low-temperature drying [16] (Certificate of Conformity UAEC No. RU D-RU.PA03.B.69039/24).

The inclusion of macro- and microelements and dietary fiber in the PPT composition was carried out by calculation [17]. The presence of minor biologically active substances in the composition of the finished product was assessed without determining their quantitative values based on the data from [18–22].

At present, the food package composition for the Arctic ration has not been specified. The nutrition of contract military personnel is organized in accordance with the norms approved in Decree No. 946⁵. In the present study, norm No. 1 (combined-arms ration) was used, taking into account additional products supplied in the regions of the Far North and the Arctic zone (canned fish, butter, cookies, condensed milk, canned green peas, squash caviar, dried fruits). The energy value of this ration (norm No. 1) is 4466.7 ± 230.7 kcal, including proteins — 165.5 ± 6.7 g, fats — 158.6 ± 16.1 g, and carbohydrates — 587.9 ± 29.4 g [6]. According to several authors, ration No. 1 provides only 45.3% of the recommended intake of vitamin A, 75.0% of vitamin C, 70.0% of vitamin B₁, 45.0% of vitamin B₂, and 77.5% of niacin, while the calcium deficit reaches 31.4% relative to the standards established by MR 2.3.1.2432-05⁶. For this reason, correction of the standard diet to compensate for deficiencies in essential micronutrients were proposed in [5–7].

In this work, we approached the task of optimizing the nutrition of contract military personnel by introducing micronutrients in the diet based on determining the clinical signs of their deficiency [12][13], taking into account data on iodine status in the population of the North [14][15]. Individuals in the main group receiving the PPP additionally received macro- and microelements, including all vitamins (specifically C, K, and A), minerals (the highest doses of Ca, I, Fe, Se, Cr, Mn), and dietary fiber (Table 1).

The maintenance of the body’s adaptive capacity and antioxidant defense system also depend on the presence of minor biologically active food substances [23] contained in plant protein products. In addition to a wide spectrum of vitamins and minerals, the composition of vegetable and berry powders includes biologically active substances such as choline, carotenoids, phytosterols, anthocyanins, lutein, zeaxanthin, beta-cryptoxanthin, organic acids, pectin, and tannins (from chokeberry). Flax seeds are rich in polyunsaturated and free fatty acids, monoacylglycerides, diacylglycerides, tocopherols, sterols, phospholipids, waxes, carotenoids, polysaccharides, and phenolic acids. Carrots are a source of polyacetylenes, falcarinol, pyrrolidine, beta-carotene, and organic acids. Broccoli contains alpha- and beta-carotene, lutein, zeaxanthin, lycopene, glucoraphanin, and phenolic compounds, and kelp contains beta-carotene, fucoxanthin, fucoidans, and alginic acid.

To assess the status of body adaptation, the leukograms of participants were analyzed in the main group before and after administration of vegetable and berry powders, and in the comparison group at baseline and on day 22 of the experiment. Blood sampling was carried out in the morning after an overnight fast into vacuum tubes (LabVac) at the Taimyr Interdistrict Hospital. Within 3 h, the samples were transported to the Central Research Laboratory of Krasnoyarsk State Medical University for performing a complete blood count using an automated hematology analyzer (Abbott, USA).

The status of body adaptation was assessed in three stages according to the method developed by Garkavi [24]. First, the type of non-specific adaptation reactions of the body was determined based on the relative lymphocyte count as a criterion indicator. The following reaction types were identified: “training reaction” — 20–27.5%; “calm activation reaction” — 28–34%; “heightened activation reaction” — 34.5–44%; “overactivation reaction” — over 40–44%.

The second stage involved the assessment of the proportions of monocytes, eosinophils, basophils, band neutrophils, and the total leukocyte count, as well as the levels of body response⁷: high, medium, low, and very low.

At the third, final stage, the adaptation state was assessed: physiological norm, pre-nosology, or disease. To that end, for each type of adaptation response, the number of individuals with different levels of body reactivity was determined. For the “calm activation” and “heightened activation” reaction types, the adaptation state was assessed as “physiological norm” (healthy) with a high or medium reactivity level, and as “pre-nosology” with a low reactivity level. For the “training” adaptation reaction type, with a high reactivity level, the adaptation state was classified as normal; with a medium reactivity level – “pre-nosology”; with a low reactivity level – “disease.” For the “overactivation” and “stress” reaction types, with a high reactivity level, the adaptation state was assessed as a manifestation of pre-nosology, and for the others — as “disease”⁸.

Statistical processing of the initial data was performed using the IBM SPSS Statistica 6.1 software package (USA). The normality of distribution was determined using the Kolmogorov–Smirnov test. For parametric data, mean values and their standard deviations (M ± SD) were calculated; for non-parametric data, the median (M_e) and interquartile range [Q₁; Q₃] were calculated. The statistical significance of differences at p < 0.05 for parametric indicators in dependent samples was calculated using Student’s t-test, and for non-parametric indicators, using the Wilcoxon test. The statistical significance of differences in assessing the effectiveness of vegetable and berry powder intake was determined using Pearson’s chi-squared test (χ²).

RESULTS AND DISCUSSION

When assessing the effectiveness of incorporating vegetable and berry powders into the diet of individuals in the main group, statistically significant differences were revealed within the reference intervals for a number of parameters, namely: a decrease in leukocyte count from 6.52 ± 0.61 to (6.3 ± 0.47) × 10⁹/L, an increase in the number of eosinophils (from 2.95 to 3.65%), monocytes (from 6.05 ± 1.88 to 6.7 ± 1.14%), and lymphocytes (from 28.2 to 39.5%). At the same time, an increase in the ratio of band neutrophils was noted, recorded at the level of the lower limit of the physiological norm, while the proportion of basophils in the subjects remained unchanged. These changes are likely associated with the enrichment of vitamin and mineral status in the participants following the intake of vegetable and berry powders (in particular, B₉, B₁₂, 25-OH-vitamin D, Fe, Ca) and the modulation of metabolic processes, manifested in the functional properties of leukocytes [25].

In the comparison group, the analyzed parameters did not show statistically significant differences over the observation period (Table 2).

Prior to the study, in 2 (6.7%) subjects from the main group, the type of adaptation reaction was classified as “heightened activation” (as the lymphocyte proportion reached 35.0–37.5%), in 14 (46.7%) individuals — as “training” (lymphocyte proportion within 20–27.5%) and “calm activation” (lymphocyte proportion within 28–34%). Following the 22-day observation period, 28 (93.3%) subjects from the main group showed the body’s adaptation reactions assessed as “heightened activation,” except for 2 (6.7%) individuals, whose adaptation reaction type was assessed as “calm activation.” These types of adaptation reactions are characterized by specific patterns in the thymic-lymphatic (immune) and endocrine subsystems of the body, corresponding to the upper range of physiological norm, where anabolic processes prevail over catabolic processes. This profile most likely represents a morphological equivalent of the participants’ adaptation to constantly acting extreme environmental factors [24].

In the comparison group, the type of adaptation reaction at baseline was assessed as “training” in 17 (56.7%) participants and as “calm activation” in 13 (43.3%) individuals. At the end of the observation period, the proportion of individuals whose adaptation reaction type was assessed as “training” increased to 19 (63.3%), while the number of individuals with the “calm activation” type decreased to 11 (36.7%).

When characterizing the levels of body response in the examined individuals over the observation period across different types of non-specific adaptation reactions, it was found that, prior to intake of vegetable and berry powders, all individuals, except for one (1.7%) participant showed the reactivity at high and medium levels. In the main group, with the “heightened activation” type, a low reactivity level was recorded in only one person. At baseline, among participants in the main group with the “training” type of adaptive reaction, reactivity levels were assessed as high in 5 (35.7%) individuals and medium in 9 (64.3%) individuals (p = 0.001). Meanwhile, among those with the “calm activation” type, a high level of body reactivity was statistically significantly determined in 2 (14.3%) subjects, and a medium level in 12 (85.7%) participants. For the “heightened activation” reaction type, in one participant from the main group at baseline, the reactivity level was assessed as medium, and in one, as low.

Over the 22-day observation period, only one individual in the main group exhibited a medium reactivity level, whereas others a high level of reactivity associated with the “heightened activation” adaptation type. Simultaneously, following 22 days, among individuals in the main group with the “calm activation” type, the level of body reactivity was statistically significantly high in all participants.

In the comparison group, conversely, the proportion of individuals with a medium level of body reactivity increased (Table 3).

Optimization of the diet was reflected in the leukogram parameters of individuals in the main group, while no changes in the comparison group were noted. This also influenced the status of body adaptation. Overall, at the beginning of observation, the adaptation state was defined as “pre-nosology” in 30% of individuals in the main group and in 23.34% in the comparison group.

Following the course of vegetable and berry powders in the main group, the adaptation state was assessed as a physiological norm in all military personnel. In the comparison group, conversely, a statistically significant (χ² = 12.0; p = 0.001) increase to 40% was noted in the proportion of individuals in a pre-nosological state of the body (see Figure). Based on leukocyte indicators and calculated leukocyte indices, it was previously established that the “pre-nosology” state is characterized by weakening of the humoral and cellular immunity and a decrease in the phagocytic activity of cells [26].

It should be noted that the observation reported in the present paper were obtained during the summer period. It can be assumed that with increasing exposure to extreme cold, the body’s adaptation response may undergo further changes.

The obtained results demonstrate the potential of multicomponent products developed using cryogenic technology and containing biologically active substances. formulations tailored to specific living conditions. These products can be used for optimizing the nutrition of military personnel and other populations operating in Arctic environments.

CONCLUSION

1. Assessment of the effectiveness of PPP inclusion in the diet of participants in the main group established a statistically significant decrease in total leukocyte count and an increase in the relative proportion of band neutrophils, eosinophils, monocytes, and lymphocytes, all within physiological norm ranges. These changes are associated with the modulation of metabolic processes affecting the functional properties of leukocytes.
2. The non-specific adaptation reactions in the majority of participants in both the main and comparison groups were classified as “training” and “calm activation” with high or medium levels of body reactivity. This is most likely due to the absence of extreme cold exposure during the study, which was conducted in the summer period.
3. Optimization of the diet was reflected in the adaptation status after the PPP course. In the main group, adaptation was assessed as a physiological norm in all military personnel, while in the comparison group, a statistically significant increase in the proportion of individuals in a pre-nosological state was observed.

Authors’ contributions. All authors confirm that their authorship meets the ICMJE criteria. The primary contributions are distributed as follows: Rofail S. Rakhmanov — development of the research design and concept, manuscript drafting; Denis A. Narutdinov — collection of primary material, statistical processing; Elena S. Bogomolova — editing, approval of the final version of the article; Sergey A. Razgulin — literature and information search.