winter immune system
During the darker and colder months of fall and winter, it is tempting to hunker down in our warm homes with big blankets and comfort food. Who doesn't want to cozy up with a big cup of hot tea, comfy slippers, and a good book?

Hibernating works for bears, bees, and bats, but unfortunately, is not ideal for humans. We require sunlight, year-round physical activity, and a steady supply of seasonal nutrients.

Fall and winter bring with them many joys (no more mosquitoes! the holidays are coming!), but they also bring with them conditions that make staying healthy a bit trickier.

For many of us, the shorter, colder days of fall and winter mean less sunlight exposure, less exercise, and less access to fresh produce.

We tend to get sick more often during fall and winter, but there are things we can do to reduce the risk.

Why do we get ill more often during colder months?

Being cold doesn't directly cause us to get sick, but cold air may contribute to conditions that lead to illness, according to a report by Healthline. Factors related to colder weather may actually be the culprits. Some viruses prefer the chillier weather, including rhinoviruses (they cause the common cold and replicate better at cooler temperatures) and influenza viruses (they peak in winter). The dry air outside and in homes with central heating may make it easier for viruses to infect dry nasal passages. Low indoor humidity and poor ventilation may also play a role. And, because we tend to spend more time inside with other people during the colder months, we are more likely to share germs.

The "Winter Blues" and Seasonal Affective Disorder can play a role, too.

The cluster of symptoms including sluggishness, lack of motivation, carbohydrate cravings, and mild depression that is known as the "winter blues" is quite common, especially for those who live in northern climates.

While the term "winter blues" is sometimes used to refer to Seasonal Affective Disorder (SAD), it is important to understand that they are NOT the same. The winter blues is a subclinical (mild) condition that does not reach the level of a mental illness. SAD is more serious and is a formally diagnosable form of depression.

Symptoms of SAD can include regularly occurring depressive symptoms (mainly excessive eating and sleeping and weight gain) during the fall and winter, full remission from the depression in the spring and summer, symptoms occurring in the past two years with no non-seasonal depressive episodes, decrease in libido, lethargy, irritability, tension, and anxiety, and cravings for sugary and/or starchy foods.

Reduced serotonin levels in the brain are believed to be a cause of SAD, and melatonin, a sleep-related hormone secreted by the pineal gland in the brain, has also been linked.

Darkness causes the body to produce more melatonin, which signals the body to prepare for sleep. Light decreases melatonin production and signals the body to prepare for being awake. Therefore, when the days are shorter and darker, our production of melatonin increases. Our brains are "tricked" into thinking it's night (even hours before we go to sleep), and we essentially go into "hibernation" mode. There is some concern that too much melatonin could worsen depression.

There are things you can do to prevent the winter blues from hitting (or to alleviate them, should they arrive): light therapy, regular exercise, and proper nutrition are among them.

Taking a supplement that provides clinically proven natural neurotransmitter modulators including SAM-e, St. John's Wort, 5-HTP, and Arctic Root may help as well.

If you believe you have SAD, you may want to seek guidance from your healthcare provider.

Boosting your immune system during fall and winter

Good nutrition will help you boost your immune system, which in turn may help you avoid catching all the cold and flu viruses that are starting to circulate.

Also, fueling your body with nutritious food will give you the energy needed to get enough exercise - and exercise has been shown to improve mood and sleep quality. According to areport from Harvard Health,
Just like a healthy diet, exercise can contribute to general good health and therefore to a healthy immune system. It may contribute even more directly by promoting good circulation, which allows the cells and substances of the immune system to move through the body freely and do their job efficiently.


For now, even though a direct beneficial link hasn't been established, it's reasonable to consider moderate regular exercise to be a beneficial arrow in the quiver of healthy living, a potentially important means for keeping your immune system healthy along with the rest of your body.
Here is a list of nutrients and foods that can help you stay healthy through fall and winter. Protein:

The immune system is made up of proteins and relies on new protein synthesis to function. The body uses amino acids found in dietary proteins to help build proteins within your body. Proteins are also part of antibodies, interferon, and complement proteins that support immune system cells or attack viruses, bacteria, or other foreign substances in the body.

Dietary sources: eggs, meat, poultry, fish, hemp, protein powder, Greek yogurt, cottage cheese, beans, almonds, pistachios, oats, quinoa

Bone broth:

Full of nutrients that can boost the immune system, including collagen (a form of protein), bone broth also contains essential amino acids including proline, glycine, and glutamine. Here are two recipes to try: Immune Boosting Bone Broth {recipes included}


Beta-carotene is a carotenoid, which means it is one of a group of plant pigments known to have antioxidant and other effects. It is a substance in plants that is quickly converted into Vitamin A inside the body. Having adequate levels of Vitamin A is key for good vision, strong immunity, and general health. It is best to obtain beta-carotene through food because it is easy to overdose (which is dangerous) via supplementation. Beta-carotene is a fat-soluble vitamin, so eating foods that contain it with a fat like olive oil or nuts can help absorption.

Dietary sources: sweet potatoes, carrots, dark leafy greens, butternut squash, cantaloupe, lettuce, red bell peppers, apricots, broccoli, and peas

Vitamin B6:

Vital to supporting biochemical reactions in the immune system. B6 deficiency can result in the decreased production of antibodies needed to fight infections and may reduce your body's production of white blood cells, including T cells (which regulate immune function, helping it respond appropriately).

Dietary sources: Poultry, meat, fish, potatoes, legumes, tofu, soybeans, chickpeas, and bananas

Vitamin B9:

Also known as folate/folic acid, Vitamin B9 is an essential nutrient that occurs naturally as folate. Folic acid is a synthetic form of B9 that the body does not convert into active vitamin B9 very well. Unmetabolized folic acid may build up in the bloodstream, which may increase cancer risk. Therefore, it is best to get Vitamin B9 from whole foods rather than from supplements.

Dietary sources: asparagus, avocados, beets, Brussels sprouts, citrus fruit, eggs, legumes, nuts, seeds, and leafy greens

Vitamin C:

Well known for its role in supporting the immune system. Vitamin C is essential for the growth and repair of tissue throughout the body. It is an antioxidant that fights free radicals and may help prevent or delay heart disease and certain cancers. High doses of Vitamin Cmay decrease the duration of colds, and a lack of the vitamin may make you more prone to getting sick. All Vitamin C supplements are not equal: a particularly good brand is called Lypo-Spheric Vitamin C - it is encapsulated in a layer of lipids, so your body digests it differently. Instead of being flushed out of your system, it's stored in your fat and liver, where it can then be utilized on an as-needed basis.

Dietary sources: Berries, broccoli, Brussels sprouts, cantaloupe, cauliflower, grapefruit, honeydew, kale, kiwi, mango, nectarine, orange, papaya, snow peas, sweet potato, strawberries, tomatoes, and red, green, or yellow peppers

Vitamin D:

Often called "the sunshine vitamin," vitamin D is unique in that it is a vitamin AND a hormone your body can make with help from the sun. Studies have shown that Vitamin D is crucial to activating our immune defenses and that without sufficient intake of the vitamin, T cells (the killer cells of the immune system) are not able to react to and fight off serious infections in the body. Because Vitamin D is fat soluble, it is possible to take too much, which can lead to over-calcification of the bones and hardening of the blood vessels, kidneys, lungs, and heart.

Dietary sources: fatty fish (like tuna, mackerel, swordfish, and salmon), beef liver, cheese, egg yolks, and fortified foods (including some dairy products, orange juice, soy milk, and cereals). For information on supplementation (it is complicated), please see How To Beat 'Cabin Fever' During The Winter With Vitamin D.

Vitamin E:

A fat-soluble nutrient, Vitamin E works as an antioxidant - it neutralizes free radicals and helps protect cells. The body needs Vitamin E to boost the immune system so that it can fight off invading bacteria and viruses. The most active form of Vitamin E is alpha-tocopherol.

Dietary sources: Almonds, broccoli (boiled), avocado, chard, hazelnut oil, mustard and turnip greens, mangoes, nuts, papaya, pumpkin, red peppers, spinach (boiled), sunflower seeds, wheat germ oil


This mineral is needed for more than 300 biochemical reactions in the body, including breaking down glucose into energy. It supports a healthy immune system, prevents inflammation associated with certain cancers, boosts heart health, and could even reduce your heart attack risk. Studies found that the mineral helps fend off depression and migraines.

Dietary sources: almonds, hazelnuts, pumpkin seeds, sunflower seeds, Brazil nuts, pine nuts, flax seed, pecans, dark chocolate, bananas, strawberries, blackberries, grapefruit, figs, yogurt


This essential nutrient neutralizes excess free radicals and protects cells from damage caused by oxidative stress. This means it helps reduce inflammation and DNA damage and helps boost the immune system. Selenium deficiency has been shown to negatively impact immune cells and may lead to a slower immune response. Caution: You can consume too much selenium, resulting in a condition called "selenium toxicity." It is rare but can be fatal, so it is important to stick to the recommended amount of 55 mcg per day and never exceed the tolerable upper limit of 400 mcg per day. Brazil nuts contain very high amounts of selenium (68-91 mcg per nut, which is about 137% of the RDI in ONE NUT), so use caution if you eat them.

Dietary sources: Brazil nuts, chicken, eggs, halibut, liver (beef or lamb), oysters, sardines, Shiitake mushrooms, sunflower seeds, turkey, wild-caught Alaskan salmon, Yellowfin tuna


This mineral keeps the immune system strong, helps heal wounds, and supports normal growth. Some studies have found that zinc lozenges may reduce the duration of a cold - perhaps by as much as 50%. It also may reduce the number of upper respiratory infections in children.

Dietary sources: oysters, crab, lobster, red meat, poultry, avocado, blackberries, fortified cereals, milk, dark chocolate, nuts, grains, legumes, beans, pumpkin seeds

Eating a variety of fresh food will help you get the nutrients you need.

In addition to the nutrients discussed above, don't forget about filling your diet with fresh produce.

While it may be harder to find the variety of fresh produce that is so abundant in spring and summer, there are fruits and vegetables that are ready to harvest during fall and winter (depending on where you live, of course). These include pomegranates, pumpkins, sweet potatoes, potatoes, onions, cabbage, Brussels sprouts, kale, broccoli, beets, carrots, turnips, rutabagas, radicchio, and citrus fruits (citrus fruits grown in warm climates are ripe for picking between late October and March).

Here's how to grow your own produce, year-round: How To Grow Vegetables Year-Round in Container Gardens.

Stay well!