Vitamins and seasonal changes: how to prepare for autumn and spring

The autumn wind is already rustling in the foliage, and spring — unexpectedly — bursts in with the first thaw and a sharp temperature drop. And every time the season changes, we notice: energy drops, mood becomes "gray," skin dries out, and immunity seems to fall asleep. This is not just "feeling unwell" — it is the body's reaction to deep biological changes related to the length of the day, the level of ultraviolet light, temperature, and even the composition of food. Vitamins here are not "supplements," but regulators of metabolism, cell protectors, and builders of the immune system. But it is important to understand: not all vitamins are equally needed in September and April. Some — for example, vitamin D — whose deficiency is particularly felt in autumn — require prevention long before you feel fatigue. Others, like vitamin C or the B group, become critically important during the active tissue renewal period in spring. And yes — this is not an advertisement for dietary supplements. This is a matter of physiology: if the body does not receive the necessary cofactors, it simply cannot function in the new mode. Therefore, preparing for the season is not about "taking a pill," but about building a support cycle that starts 4–6 weeks before the weather changes.

Classification according to ICD-11: deficiency states and seasonal adaptation disorders

In the International Classification of Diseases 11th Revision (ICD-11), there is no separate code for "seasonal weakness" — because it is not a diagnosis, but a syndrome caused by a complex of factors. However, the main underlying causes have clear codes:

• EN50.0–EN50.9 — vitamin D deficiency (including rickets in children and osteomalacia in adults);
• EN51.0–EN51.9 — vitamin C deficiency (scurvy and its precursors);
• EN52.0–EN52.9 — deficiency of B vitamins (especially B1, B2, B6, B12, and folic acid);
• EN53.0–EN53.9 — vitamin A deficiency (xerophthalmia, hyperkeratosis);
• EN54.0–EN54.9 — vitamin E deficiency (neurological disorders, hemolytic anemia);
• QE85.0 — "Seasonal Affective Disorder" (SAD), related to changes in light patterns;
• QA70.0 — "Immunosuppression caused by nutrient deficiency."

Important: most people experiencing "autumn apathy" or "spring fatigue" do not suffer from clinical deficiency — but are in the zone of **functional deficiency**. That is, the level of vitamins in the blood is still within the norm, but not sufficient for the optimal functioning of enzyme systems. For example, with a concentration of 25(OH)D = 28 ng/ml, a person formally does not have a vitamin D deficiency (below 20 ng/ml — deficiency), but to maintain immune activity and serotonin synthesis, a minimum of 35–40 ng/ml is recommended. It is this "gray zone" that explains why some feel great in September, while others feel like they have gone three days without sleep.

The history of seasonal vitamin problems: from seasickness to polar expeditions

As early as the 18th century, English physician James Lind conducted the first controlled clinical experiment: he gave a group of sailors lemon juice — and those who received it did not get scurvy. Before that, it was believed that the disease was caused by "bad air" or dirt on ships. Lind proved: it is a deficiency of a substance found in fresh fruits. His work laid the foundation for a scientific approach to nutrition.
But what is more interesting is how people coped with seasonal hunger before the advent of vitamin supplements. In Scandinavia, where the sun hardly shines in winter, they used **fermented fish oil** — a source of vitamin D and Omega-3. In Russia — salted caviar, cod liver, sauerkraut (a source of vitamin C). In Japan — nori seaweed and miso — rich in B vitamins and trace elements. These traditions were not random: they were formed over centuries under the pressure of natural selection. Those who preserved vitamin reserves survived winter better and passed their genes to the next generation.
In the 20th century, with the advent of synthetic vitamins, the situation changed dramatically: in the 1930s, vitamin C began to be produced in tablets, and in the 1940s — vitamin D in the form of an oily solution. But here’s the paradox: the more vitamins we began to consume in the form of dietary supplements, the more often the **syndrome of excessive intake** arose — especially among those who take "immune complexes" without blood tests. For example, chronic overdose of vitamin A leads to headaches, dry skin, and even increased intracranial pressure. And excess vitamin D leads to hypercalcemia and kidney stones. So the story is not only about deficiency — it is also about balance.

Epidemiology: how many people actually suffer from seasonal vitamin imbalance?

According to Rospotrebnadzor (2024), during the autumn-winter period, vitamin D deficiency is identified in **68% of the adult population** of Russia, including:

• 74% of women aged 25–45;
• 62% of men aged 30–50;
• 81% of elderly people over 65 years old.

These figures confirm the research of the Institute of Nutrition of the Russian Academy of Sciences: a level of 25(OH)D below 30 ng/ml is observed in 2/3 of urban residents in November–February. At the same time, only 12% of them take vitamin D prophylactically.
As for vitamin C: according to WHO, the average daily intake for adults in Russia is 55–65 mg, while the recommended norm is 90 mg for men and 75 mg for women (and up to 120 mg when smoking or under stress). In 41% of respondents in the "Rosstat-2025" study, a level below 50 mg/day was recorded — especially in regions with limited access to fresh vegetables and fruits.
Risk groups:

• Residents of northern latitudes (Murmansk, Norilsk, Yakutsk) — due to the lack of UV radiation for 5–7 months a year;
• People with dark skin — melanin blocks the synthesis of vitamin D, requiring 3–6 times more sunlight;
• Patients with gastrointestinal diseases (Crohn's disease, celiac disease) — impaired absorption of fat-soluble vitamins;
• Elderly — reduced kidney and liver function, which are involved in the activation of vitamin D;
• Teenagers and students — high energy expenditure with irregular nutrition.

An interesting fact: in 2023, a mass screening was conducted in the Yaroslavl region — and it turned out that among high school students in grades 9–11, the level of vitamin D in October was on average 22% lower than in May. At the same time, 64% of them received no prophylaxis. This is not "weakness" — it is a physiological reality that cannot be ignored.

Genetic predisposition: why do some people cope with autumn easily, while others do not?

Not everyone absorbs vitamins equally — and this depends on genes. The most studied example is polymorphisms in the gene CYP2R1 and GC, responsible for the metabolism of vitamin D. In people with the rs10741657 variant (A-allele), the synthesis of 25(OH)D in the liver is reduced by 15–20% compared to the G-allele. This means that even with the same sun exposure and supplement intake, their levels will be lower.
Another key gene — MTHFR (methylenetetrahydrofolate reductase). Its C677T mutation occurs in 30–40% of the Russian-speaking population and leads to reduced absorption of folic acid (vitamin B9). This is especially important in the fall when the body prepares to recover from summer stress: folate is involved in DNA synthesis and cell regeneration. People with this mutation often suffer from fatigue, dizziness, and sleep disturbances — and they need not just "vitamin B," but specifically **methylfolate** (the active form).
The gene SLC23A1 encodes the vitamin C transporter in the intestine. The rs33972313 polymorphism reduces the absorption of ascorbic acid by 10–15%. This explains why some people can drink a liter of orange juice and still have low levels of vitamin C in their blood.
And yes — genetics is not destiny. But knowing your genotype (for example, through tests like Genotek or Invitro) allows for personalized prevention. If you have the MTHFR mutation — it’s not worth buying cheap complexes with folic acid: they will be ineffective. It’s better to choose a form with methylfolate and vitamin B12 in the form of methylcobalamin. This is not "expensive," but **rational**.

Risk factors: what besides the weather affects your vitamin balance?

The season is just a trigger. The real imbalance is formed under the influence of many factors:
Physical:

• Lack of UV radiation — the main factor of autumn D deficiency. In 1 hour outdoors in September on a clear day, you synthesize ~200–400 IU of vitamin D, while in January — less than 50 IU;
• Chronic stress — increases the consumption of vitamins B1, B5, C, and magnesium. Adrenaline and cortisol "burn" these cofactors as fuel;
• Low physical activity — slows down circulation and metabolism, reducing the delivery of vitamins to tissues.

Chemical and dietary:

• Caffeine and alcohol — increase the excretion of vitamins B and C through the kidneys;
• Smoking — reduces vitamin C levels by 25–40% due to oxidative stress;
• Abundance of refined carbohydrates — leads to a deficiency of B1 (thiamine), as its metabolism is linked to glucose;
• The intake of certain medications: anticonvulsants (carbamazepine), hormonal contraceptives, statins — reduce levels of vitamins D, E, K, and the B group.

The combination is especially dangerous: for example, a 35-year-old woman, working in an office, drinks 3 cups of coffee a day, smokes, takes OCs — and in September complains of fatigue. Here it’s not "autumn," but a **combination of factors** that can be corrected. And yes — even if you eat "healthy" food, but it is low in fats, you will not absorb vitamins A, D, E, K. Because they are fat-soluble. Without oil, avocado, or nuts — they will simply be excreted with feces.

Diagnosis: how to understand that you are lacking vitamins, and it’s not just "you are tired"?

The first step is not to rush to the pharmacy, but to pay attention to **typical symptoms**:

• Vitamin D: chronic fatigue, joint and muscle pain, frequent ARVI, depressive states, dry skin;
• Vitamin C: bleeding gums, slow wound healing, brittle nails, "spots" on the skin (petechiae);
• B vitamins: numbness of limbs (B12), peeling skin around the nose (B2), cracks in the corners of the mouth (B6), irritability and sleep disturbances (B1, B6);
• Vitamin A: "night blindness" (difficulty seeing in twilight), dry eyes, frequent conjunctivitis;
• Vitamin E: muscle weakness, coordination disorders, anemia.

But symptoms are just a hint. Accurate diagnosis requires tests:

Important: do not take "everything at once." It is better to start with 25(OH)D and a complete blood count (CBC + CRP) to rule out anemia or inflammation. If the D level is low — check parathyroid hormone (PTH): in case of D deficiency, it increases, indicating secondary hyperparathyroidism. This is already a serious signal — it requires not just taking a vitamin, but monitoring after 3 months.

Treatment: how to replenish the deficiency — correctly and safely

Treatment is not "take a pill for a month." It is a **correction cycle**, consisting of three stages:
1. Loading phase (2–4 weeks)
The goal is to quickly raise the level to therapeutic. Examples:

• Vitamin D: 5000–10,000 IU/day orally (oil solution or capsules). No more than 4 weeks without monitoring;
• Vitamin C: 500–1000 mg twice a day (preferably in the form of sodium ascorbate — less irritating to the stomach);
• Group B: complex with methylfolate and methylcobalamin — 1 tablet in the morning.

2. Maintenance phase (3–6 months)
Goal — to maintain the level at optimum:

• Vitamin D: 1000–2000 IU/day (or 10,000 IU twice a week);
• Vitamin C: 200–500 mg/day (can be with food — for example, 1 orange + ½ cup of sauerkraut = ~150 mg);
• B-complex: once a day, preferably in the first half of the day (to avoid disrupting sleep).

3. Prophylactic phase (seasonal)
Start 4 weeks before the change of season:

• In autumn: D + C + zinc (15 mg/day) — for immune preparation;
• In spring: B-complex + magnesium (200–300 mg) + vitamin E (100 IU) — for restoring the nervous system and antioxidant protection.

Important: the intake of vitamins should be **related to food intake**. Fat-soluble (A, D, E, K) — with fatty foods (olive oil, avocado, fish). Water-soluble (C, B) — better in the morning, before 2 PM, to avoid interfering with sleep. And never combine vitamin D with calcium without a prescription — this can lead to hypercalcemia.

List of medications: which forms really work

Not all vitamins are equally absorbed. Here are proven forms, confirmed by clinical studies:

• Vitamin D3 (cholecalciferol) — better than D2. Forms: drops in olive oil (for example, "Devisol"), capsules with MCT oil ("D3+K2" from Now Foods), or tablets with lecithin. Avoid alcohol solutions — they are poorly absorbed;
• Vitamin C: sodium ascorbate (less irritating to the gastrointestinal tract), ascorbyl glucoside (stable form), or liposomal C (high bioavailability, but more expensive);
• Folic acid: only in the form of 5-methyltetrahydrofolate (5-MTHF)
• Vitamin B12: methylcobalamin or adenosylcobalamin — not cyanocobalamin (it contains cyanide in microdoses, and it needs to be detoxified);
• Vitamin E: a mixture of tocopherols (alpha-, beta-, gamma-), not just alpha-tocopherol — this protects cells more effectively.

An example of a proven complex for autumn:

• Vitamin D3 — 2000 IU
• Vitamin C — 300 mg
• Zinc — 15 mg (in the form of picolinate)
• Selenium — 55 mcg
• Vitamins B6, B12, folate (in active forms)

This composition supports immunity, reduces inflammation, and improves mood — without excess. And yes — cheap "multivitamins" often contain insufficient doses of D and C, but excess iron and copper, which can exacerbate oxidative stress. Choose based on composition, not price.

Monitoring and forecasting: how not to "overdo it" and when to expect results

After starting vitamin intake, it is important to monitor the effect — and not just based on how you feel.
Control deadlines:
<ul liIn 4 weeks — repeat 25(OH)D (if there was a deficiency);

The prognosis is favorable with timely correction. In 85% patients, vitamin D levels normalize in 8–12 weeks with the correct dosage. But there are nuances:

• If the D level does not rise — check liver and kidney function. An injectable form may be needed;
• If fatigue persists — the deficiency may not be the only factor: check ferritin (iron stores), thyroid (TSH, free T4), and cortisol levels;
• With prolonged intake (>6 months) of vitamin A or D — calcium and phosphates in the blood are mandatory.
• Chronic D deficiency → osteoporosis, muscle weakness, increased risk of heart attack;
• B12 deficiency → irreversible neurological damage (ataxia, dementia);
• Vitamin C deficiency → scurvy (rare, but occurs in people with an extremely poor diet).

But remember: vitamins are not medicines. They do not cure the flu, but make the body more resilient to it. Like a shield — it does not stop the blow, but reduces the damage.

Age-related features: how needs change over the years

Children (up to 18 years):

• Vitamin D — 600–1000 IU/day (depending on age). Critical for bone growth and immunity;
• Vitamin C — 45–75 mg (depending on age). Deficiency manifests as frequent sore throats and slow healing;
• Important: children absorb vitamins better, but often refuse vegetables — therefore, forms such as chewable tablets or syrups should be sugar-free and dye-free.

Adults (18–60 years):

• The main focus is on D, B-complex, and antioxidants (C, E, selenium);
• Women of reproductive age need more folate (400 mcg) — especially when planning a pregnancy;
• Men need zinc and selenium to support reproductive function.

Elderly (over 60):

• Decreased gastric juice secretion → poor absorption of B12. Requires either injections or sublingual forms;
• Decreased synthesis of vitamin D in the skin — by 75% compared to youth. Therefore, the dose of D should be higher (80–2000 IU);
• Risk of K2 deficiency — leads to calcium deposition in blood vessels. Therefore, the D3+K2 complex is the optimal choice.

Interesting point: in people over 70, the level of vitamin B6 in the blood is often elevated not due to excess, but due to metabolic disorders — and this also requires correction. Therefore, age is not just a number, but a parameter that changes the entire support strategy.

Questions and answers: the most frequent user inquiries

Question 1: Can I take vitamin D in the summer if there is no deficiency?
Yes, but wisely. If the level of 25(OH)D is above 40 ng/ml — additional intake is not needed. Excess D is not excreted like water-soluble vitamins and can accumulate. It is better to take a test in June — and if everything is normal, limit yourself to sunbathing (15–20 min a day, without sunscreen, on hands and face). But in August — start prevention: from September, synthesis drops sharply.
Question 2: Why do I take vitamin C but still get sick often?
Vitamin C is not an immune stimulant, but an antioxidant and cofactor for collagen and interferon synthesis. Its deficiency reduces protection, but excess does not make you "immune." Frequent ARVI may be related to D, zinc deficiency, or microbiome disruption. Check levels of D and selenium — they work in conjunction with C.
Question 3: Which vitamin helps with autumn depression?
Not one. Seasonal affective disorder (SAD) is associated with a disruption in the synthesis of serotonin and melatonin. Key participants:

• Vitamin D — regulates serotonin receptors;
• Vitamin B6 — necessary for converting tryptophan into serotonin;
• Magnesium — stabilizes the nervous system;
• Omega-3 (EPA+DHA) — improve the fluidity of cell membranes in the brain.

Comprehensive support yields results faster than a single vitamin.
Question 4: Can vitamins be replaced by food?
Yes — but only with a varied diet. For example:

• Vitamin D: 100 g of cod liver = 3000 IU, 1 egg (yolk) = 40 IU, 100 g of salmon = 500 IU;
• Vitamin C: 1 orange = 70 mg, 100 g of sauerkraut = 20 mg, 1 chili pepper = 240 mg;
• Vitamin B12: 100 g of beef liver = 60 mcg (100 times the daily norm!).

But in urban conditions, where fresh products are expensive and not always of good quality, dietary supplements are a rational addition, not a replacement.
2>Typical mistakes and how to avoid them
Mistake 1: “I take vitamins, so I can eat anything”**
No. Vitamins do not compensate for a deficiency of protein, fats, or fiber. Without proper nutrition, supplements work 30–50% less effectively. Example: vitamin D without fat — will not be absorbed. Vitamin C with coffee — will be excreted faster.
Mistake 2: Taking all vitamins in the morning “on an empty stomach”**
Fat-soluble vitamins (A, D, E, K) on an empty stomach — are almost not absorbed. Water-soluble (C, B) — can irritate the mucosa. Better: B-complex — with breakfast, D — with lunch (with fatty food), C — between meals.
Mistake 3: Prolonged intake of the same complex without control**
The body adapts. After 3–4 months, effectiveness decreases. Rotation is needed: for example, in autumn — D+C+zinc, in winter — B-complex+magnesium, in spring — antioxidants (E, selenium, quercetin).
Mistake 4: Ignoring interactions**
Vitamin E reduces the effectiveness of vitamin K (risk of bleeding). Zinc in large doses blocks the absorption of copper. Iron reduces the absorption of zinc and calcium. Therefore — read the composition, and do not mix dietary supplements without consultation.
What to do instead:

Autumn and spring are not a reason for panic, but a natural cycle that our body knows how to overcome. But only if we provide it with the necessary tools. Vitamins are not "magic pills," but biochemical keys that trigger recovery, protection, and adaptation processes. The main thing is to act consciously: know your level, understand which forms work, and not confuse prevention with treatment.
If your task is to prepare for the season — start with a 25(OH)D test and a general blood test. Then — choose support based on your age, lifestyle, and genetics. And remember: the best prevention is not what you take, but how you live. Light, movement, sleep, and a varied diet are the foundation. Vitamins are just an enhancer of this foundation.
You are not a "superhuman" in autumn. You can be healthy — simply because you know how to help your body. And yes — if in doubt, consult a doctor. Not a "social media expert," but someone who sees your tests and listens to your story. Because your body is unique. And it deserves precise, not template support.