Staying Healthy Through Fall and Winter: 5 Essential Nutrients for Your Immune System

As temperatures drop and the days grow shorter, cold season begins. Right now, many people are wondering how they can boost their immune systems and stay as healthy as possible through the fall and winter.

A balanced diet is key to this. Our bodies need various vitamins and minerals so that the immune system can function properly. But which nutrients are particularly important? Which foods contain them? And are dietary supplements really necessary during the cold season?

We’ll introduce five important nutrients, explain what the science says about them, and offer practical tips for everyday life.

1. Vitamin D: The Winter Must-Have

Vitamin D has a unique feature: Our bodies can produce it on their own with the help of sunlight. However, the skin needs sufficient UV-B radiation to do so.

In our part of the world, this is only possible to a limited extent during the winter months. How well we are supplied with vitamin D therefore also depends on how much vitamin D our bodies have produced and stored during the sunnier months.

Vitamin D contributes to the normal functioning of the immune system. It is also important for maintaining normal bones and normal muscle function.

What foods contain vitamin D?

  • Fatty fish: such as herring, salmon, and mackerel
  • Eggs: especially the egg yolk
  • Mushrooms: especially those that have been exposed to UV light

When the body cannot produce enough vitamin D on its own, it is often difficult to obtain sufficient amounts through diet alone.

Does that mean you automatically need a supplement in the winter?

Not necessarily. Individual vitamin D levels depend on various factors, such as age, sun exposure, and the body’s vitamin D stores. If there is an increased risk of deficiency, it may be advisable to consult a doctor.

It is also important to distinguish between an adequate intake of vitamin D and the preventive effects of additional supplements: A large meta-analysis conducted in 2025 found no statistically significant protective effect of vitamin D supplementation against acute respiratory infections overall.

2. Zinc: An important nutrient for our immune system

Zinc is one of the essential trace minerals. Our bodies need it for numerous processes, including the normal functioning of the immune system, cell division, and the protection of cells against oxidative stress.

Since the body does not store large amounts of zinc, it is important to get a regular supply through the diet.

These foods are good sources of zinc:

  • Pumpkin seeds and cashews
  • Oatmeal and whole-grain products
  • Lentils and chickpeas
  • Meat, Cheese, and Seafood

Zinc is especially easy to incorporate into fall meals: a hearty lentil stew, oatmeal for breakfast, or toasted pumpkin seeds sprinkled on top of pumpkin soup add variety to your meal plan.

Can zinc also help with a cold?

A Cochrane review from 2024 examined whether zinc supplements can prevent colds or shorten their duration. The results suggest that certain zinc supplements may reduce the duration of an existing cold. However, the scientific evidence is limited, and no clear preventive effect has been demonstrated.

Taking high doses on your own is therefore not recommended. Among other things, too much zinc can interfere with copper absorption.

3. Vitamin C: The classic choice for the cold season

Hardly any other vitamin is as frequently associated with the immune system as vitamin C. And for good reason: It contributes to the normal function of the immune system, helps protect cells from oxidative stress, and supports normal collagen formation.

Nevertheless, one myth persists: If you take a lot of vitamin C, you won't catch a cold.

The scientific evidence paints a more nuanced picture. A Cochrane review shows that regular use of vitamin C supplements does not prevent colds in the general population. However, it may slightly shorten the duration of symptoms.

To ensure you're getting enough nutrients, it's especially worth taking a look at your daily meal plan.

These foods are particularly rich in vitamin C:

  • Red bell peppers: contain even more vitamin C per 100 grams than oranges
  • Broccoli and Brussels sprouts: they're perfect for fall and winter cooking
  • Kiwis and citrus fruits: a refreshing change of pace during the cold season

Our tip: Vitamin C is sensitive to prolonged exposure to heat. Therefore, cook vegetables as gently as possible and be sure to include fresh fruit or raw vegetables in your diet on a regular basis.

4. Vitamin A: Focus on the Natural Protective Barrier

For many people, squash, carrots, and sweet potatoes are staples of fall cuisine. They owe their vibrant colors in part to carotenoids such as beta-carotene, which our bodies can convert into vitamin A when needed.

Vitamin A is important for maintaining healthy skin and mucous membranes. These form our body's natural barriers. In addition, vitamin A contributes to the normal functioning of the immune system.

These foods provide vitamin A or its precursors:

  • Pumpkin and Carrots
  • Sweet Potatoes
  • Spinach and other green leafy vegetables
  • Eggs and certain dairy products

Especially handy: Many of these foods are perfect for making comforting dishes—such as pumpkin soup, roasted vegetables, or a hearty vegetable stew.

Good to know: Beta-carotene is fat-soluble. Adding a little olive or canola oil to your vegetables can improve its absorption.

5. Selenium: An Often Underestimated Trace Element

Selenium is much less often the focus of attention than vitamin C or vitamin D. Yet it plays important roles in the body.

This essential trace element is a component of various enzymes and contributes, among other things, to the normal functioning of the immune system, the protection of cells from oxidative stress, and normal thyroid function.

Where can you find selenium?

  • Fish and Seafood
  • Eggs and Meat
  • Grain products, depending on the selenium content of the soil
  • Brazil nuts

Brazil nuts, in particular, are often cited as an especially good source of selenium. In fact, they can contain very high amounts. However, their selenium content varies widely, making it difficult to estimate the amount consumed.

The same principle applies here: More is not automatically better. A chronically excessive intake of selenium can have health consequences. The key is to ensure an intake that meets your needs.

Shorter days, less energy? What's good for our bodies right now

When it gets light later in the morning and dark earlier in the evening, daily life changes for many people. Maybe it’s harder to get out of bed, or you feel less like exercising than you do in the summer.

Our internal clock plays an important role in this. It is influenced, among other things, by natural daylight and affects our sleep-wake cycle. The switch to standard time can also temporarily alter this cycle.

Right now, it's worth paying attention to a few simple habits:

  • Making the Most of Daylight: Natural light, especially in the morning, is an important cue for our internal clock.
  • Stay Active: Whether it's a walk, a bike ride, or a workout—regular exercise supports overall health and well-being.
  • Get enough sleep: For most adults, seven to nine hours of sleep per night is a good guideline.
  • Plan intentional breaks: Short breaks and plenty of rest can help make the often-hectic days leading up to the end of the year more enjoyable.

A varied diet, adequate sleep, and regular exercise form a solid foundation for a healthy daily routine—not just in the fall and winter. At the same time, numerous metabolic processes take place in our bodies around the clock, involving not only vitamins and minerals but also various molecules produced by the body itself.

A Look Inside Our Cells: What Role Does NADH Play?

One of these molecules is NADH (coenzyme 1), the reduced form of nicotinamide adenine dinucleotide (NAD).

NADH is produced during various metabolic reactions and plays an important role as an electron carrier. In the mitochondria, it transfers these electrons to the respiratory chain. The processes that take place here are involved in the production of ATP (adenosine triphosphate)—the most important immediately usable energy source in our cells.

If you're interested in learning more about the biochemical background, you'll find additional information on our "About NADH" page.

Conclusion: Well-prepared for the cold season

A balanced diet is an important foundation for good health, even in the fall and winter. Vitamin D, vitamin C, vitamin A, zinc, and selenium each play different roles and, among other things, help the immune system function normally.

People who eat a varied diet and also make sure to get enough sleep, exercise, and rest create the right conditions for their own well-being. Dietary supplements can be helpful when needed, but they are no substitute for a balanced diet.



Scientific Sources and Additional Information

  1. German Nutrition Society (DGE): FAQ on Vitamin D (based on the 2025 D-A-CH Reference Values). https://www.dge.de/gesunde-ernaehrung/faq/vitamin-d/
  2. Jolliffe D. A. et al. (2025): Vitamin D supplementation to prevent acute respiratory infections: systematic review and meta-analysis of stratified aggregate data. The Lancet Diabetes & Endocrinology. https://doi.org/10.1016/S2213-8587(24)00348-6
  3. Nault D. et al. (2024): Zinc for the prevention and treatment of the common cold. Cochrane Database of Systematic Reviews. https://doi.org/10.1002/14651858.CD014914.pub2
  4. Hemilä, H., & Chalker, E. (2013): Vitamin C for preventing and treating the common cold. Cochrane Database of Systematic Reviews. https://doi.org/10.1002/14651858.CD000980.pub4
  5. National Institutes of Health, Office of Dietary Supplements: Dietary Supplements for Immune Function and Infectious Diseases – Health Professional Fact Sheet. https://ods.od.nih.gov/factsheets/ImmuneFunction-HealthProfessional/
  6. National Institutes of Health, Office of Dietary Supplements: Selenium – Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/Selenium-HealthProfessional/
  7. National Center for Biotechnology Information: Electron Transport Chain. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK526105/

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FAQs

Vitamin C, vitamin D, and vitamin A contribute to the normal functioning of the immune system. The trace minerals zinc and selenium also play important roles. What matters most is ensuring an adequate intake of all essential nutrients—not consuming as much of individual vitamins as possible.

A varied diet that includes vegetables, fruits, whole grains, legumes, and nuts provides many important nutrients. Pumpkins, carrots, cabbage, bell peppers, and lentils are especially good choices in the fall and winter. However, no single food can replace a balanced diet.

In our part of the world, the body’s ability to produce vitamin D is often limited during the winter months. Whether supplementation is advisable depends, among other things, on age, sun exposure, and individual vitamin D levels. If there is an increased risk of deficiency, it is recommended to consult a doctor.

Vitamin C supports the normal function of the immune system. However, studies show that taking it regularly as a supplement does not prevent colds in most people. It may slightly shorten the duration of a cold.

Adequate sleep, regular exercise, rest, and managing stress effectively are important components of a healthy lifestyle. Especially during the darker months of the year, it can also be helpful to get regular exposure to daylight and maintain as consistent a sleep schedule as possible.