With the weather turning dark and rainy as winter approaches in the Seattle area, people are at a higher risk for infections. In addition to staying up to date on vaccines, washing your hands frequently, and avoiding sick contacts, a nutrient-rich diet also plays a key role in maintaining your overall health and helping your body fight off infections. While eating a varied, well-balanced diet can provide plenty of vitamins for some people, nobody is perfect. Supplements can be a helpful way to ensure you are receiving enough essential vitamins. The following are some supplements that are commonly recommended in winter. Please note that no vitamin or herbal product has been proven to reduce the risk of the common cold. Supplements are also not a one-size-fits-all. Before starting a new product, we always recommend speaking to your doctor to ensure it is safe and recommended for you.


When you think of vitamin D, you may think of the sun. This is because sunlight is the main source for humans. For people that live in places that don’t get much sun in winter, they must rely on diet and supplements to get vitamin D. Certain foods such as cod liver oil, salmon, tuna, and egg yolk do contain vitamin D, but in very small amounts. This makes it difficult to get the daily recommended amount from food alone. Supplements are a helpful way to fill in this gap. Vitamin D is important to keep our bones strong and to prevent infections. Although there is limited data, it also might help improve mood, which can be good for patients that tend to feel more down in the winter months. Usually Seattle does not receive much sun in winter, so a vitamin D supplement is recommended for most people. The recommended daily dose for patients age 19 and older is 600 iu (15 mcg) daily. For patients 70 years and older 800 iu (20 mcg) daily. The Mayo Clinic states up to 2,000 iu (50 mcg) a day is considered safe. If you have questions, your doctor or pharmacist can help you decide what dose is right for you.

Vitamin C
Vitamin C has a role in our immune system function. There is a common myth that vitamin C prevents colds. While it can’t prevent colds, it has been found to reduce how sick you get and how long you are sick for. There are a lot of foods that contain vitamin C such as oranges, kiwi, strawberries, broccoli, and many other fruits/veggies. While vitamin C from diet alone is enough for most adults, a supplement may be helpful to reach the recommended daily amount if you find you don’t eat a lot of fruits and veggies in the winter months. For adults 19 years and older the recommended daily dose is 90 mg for males and 75 mg for females, but up to 2 g (2,000 mg) a day is considered safe. 

Zinc is important for human growth, wound healing, and breaking down carbs we eat. Data has been inconsistent, but a few trials have found zinc reduced the risk of colds when taken for at least five months. Zinc may not be right for everyone as it can interact with certain medications, such as some antibiotics and antiviral medicines. Dietary sources of zinc include fish, meat, beans, and several other foods.

B Vitamins
There are many B vitamins, each with important roles in maintaining nerve function, turning our food to energy, boosting mood, hair and nail health, and supporting a strong immune system. B-12 in particular can be helpful in winter and can be found in a variety of foods such as salmon, eggs, almonds, and leafy greens.

Non-Medicinal Ways to Stay Healthy in Winter

  • Wash hands frequently, especially before making food or eating
  • Get plenty of sleep, at least 7 hours a night is recommended. People that get <5 hours of sleep a night have around 3x the risk of catching a cold compared to those that sleep >7 hours.
  • Wear face masks, especially in crowded areas. Face masks reduce the spread of infections we spread through our breath by up to 90%, which lowers the spread of respiratory infections.
  • Avoid sick contacts. If a family or friend feels ill, it is best to avoid visiting with them to avoid getting sick as well.
  • Exercising regularly, the general recommendation being at least 30 minutes of moderate-intense physical activity 3 days a week and some strength training.

Myth vs. Fact?

“You can’t have too much of a vitamin”
False – Fat-soluble vitamins can build up in the body and in some cases can even be harmful. The fat-soluble vitamins are A, D, E, and K. Here is what to look out for if you might be getting too much of one of these vitamins.

  • Vitamin A: confusion, hair loss, liver damage, bone loss, and increased risk of lung issues for those with a history of smoking
  • Vitamin D: generally safe even at high doses
  • Vitamin E: increased risk of bleeding, including brain bleeds
  • Vitamin K: increases risk of blood clots (which can cause heart attacks and strokes)

“A varied diet alone can provide enough vitamins  in certain cases”
True – Some vitamins are found in many foods and are easy to get enough of. Others are more difficult, but not impossible. In general, eating a wide variety of fruits, veggies, whole-grains, and lean sources of protein is the best approach to getting lots of nutrients.

“All vitamin brands are identical”
False – Unlike medications, supplements are not regulated by the Food and Drug Administration (FDA). Before buying a product, it is recommended to check the bottle to see if it is endorsed by the United States Pharmacopeia (USP), which is a non-profit organization that tests products and to make sure their products are what they claim to be. While this is not a guarantee of the quality, it provides some reassurance of the brand. Additionally, you can also check with your pharmacist or doctor if you have any questions regarding which supplement to purchase.

Prepared by Leah Topp, PharmD Candidate 2024


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