
While it is important to stay healthy & keep your immunity up all year round, it is especially important during the fall and winter here in the U.S. The months of December through February are the time of year considered to be the peak of the cold & flu season, and during this time, it's especially important to keep your defenses up.
Your immune system – which is your body’s natural defense system - is your main line of protection from and defense against all of the things that can make you sick. There are many factors that can influence and affect the way your immune system works - and if it’s not performing as well as it should be, you are more likely to get sick.
Unfortunately, many people fall into one (or more) of the following groups that are often considered to be immunocompromised (means your immune system isn’t functioning as well as it should be):

Older and elderly adults (waning immunity is associated with natural age progression and higher incidence of chronic underlying illness; poor nutrition can also be a factor in some cases)
Overweight and obese individuals (these two conditions cause chronic inflammation in the body that over time leads to a weakened immune system)
Individuals suffering from nutrient deficiencies (poor diets or diets lacking in vitamins and minerals can lead to a weakened state of immunity)
Individuals suffering from chronic diseases (some chronic diseases and conditions destroy immune cells which weakens your immunity; other conditions known as autoimmune diseases cause the immune system to malfunction and attack healthy tissues within your body, often resulting in chronic inflammation as well)
Individuals dealing with chronic stress (stress and anxiety cause your body to produce higher levels of the stress hormone cortisol which can lead to chronic inflammation when your body is unable to return the hormone to a normal level; stress also decreases certain immune cells that help to fight off viruses and bacteria)
Those who are not regularly getting enough sleep (sleep is a restorative time for your body and lack of sleep can lead to a decrease in the production of certain immune cells; lack of sleep often also increases cortisol levels in the blood)

Being immunocompromised increases the likelihood
of becoming seriously ill from viruses like Covid 19 and the flu.

A LITTLE BIT ABOUT YOUR IMMUNE SYSTEM
Most people don’t know it, but your digestive tract houses a large part of your immune system (there are many immune cells located in the intestines). For that reason, it’s extremely important to keep your gut microbiome healthy and flourishing.
The gut microbiome is a collection of bacteria and microorganisms that live in the intestines and help break down food during digestion (making many nutrients easier for the body to absorb). These microorganisms also help regulate immune cells.
Many foods that are part of a balanced diet - like nutrient dense foods that are high in fiber, foods with little to no added sugar, and foods that contain probiotics (healthy bacteria) - help support a healthy gut microbiome.

If your intestinal flora (gut microbiome) is out of balance, it can cause
chronic inflammation inside the body that will weaken your immune system.
KEEPING YOUR IMMUNE SYSTEM HEALTHY
There is no shortage of advice from the nutrition industry (some good, some bad) on ways to do this. But don’t be fooled. While there are foods & nutrients that are essential for supporting a healthy immune system, there is not one food or one nutrient alone that can boost your immune system and keep you free from illness.
For optimal overall and immune health, you must focus on a balanced diet that includes a wide range of nutrients, vitamins, and minerals. Consistently consuming the right balance of nutrients is the best way to nutritionally support a healthy immune system.
8 NUTRIENTS THAT SUPPORT A HEALTHY IMMUNE SYSTEM

Nutrients are substances found in food that our bodies need for energy, cell development & growth, and to maintain healthy function. Nutrients include proteins, carbohydrates, fats, vitamins & minerals.
Below is a list of 8 nutrients that are key to keeping your immune system healthy and strong, as well as some foods that are good sources of these nutrients.
While this isn’t a complete list of food sources, having some or all of these in your daily/weekly diet will help you to meet your daily requirements of many nutrients AND help keep you healthy.
1) Vitamin C
Vitamin C is a nutrient that your body uses in the production of many different types of cells. It can also help protect your body’s cells from damage and is a vital part of the healing process.
Some great whole food sources of Vitamin C are:
Oranges
Grapefruit
Strawberries
Kiwi
Tomatoes
Broccoli
Cauliflower
Brussels Sprouts
Cabbage
Kale & Spinach
Peas
Potatoes
Bell peppers
2) Vitamin D
In additional to supporting immune health, Vitamin D is a nutrient that is important for healthy bones and muscles, and for regulating many cellular processes in the body.
Vitamin D can be found in some fortified foods like:
Milk
Yogurt
Orange juice
Cereal
As well as some great whole food sources such as:
Salmon
Canned tuna
Egg Yolks
Mushrooms
3) Zinc
Zinc is a mineral that has multiple functions in the body - including helping to balance hormones, supporting metabolic functions, and assisting your immune system by helping to fight off viruses and bacteria.
The best food sources of zinc are:
Meats (beef, poultry and pork)
Shellfish/seafood (oysters, crab, lobster, shrimp)
Some plant-based food sources of zinc are:
Legumes – like beans, chickpeas & lentils
Nuts – cashews, peanuts, pecans, almonds, pine nuts & walnuts
Seeds – pumpkin, sesame, flax
4) Selenium
Selenium is a mineral that helps supports thyroid function and acts as an antioxidant – helping to reduce inflammation in the body, which ultimately helps to boost your immune system’s function.
The foods that are highest in selenium are:
Brazil Nuts
Some fish & seafood like yellowfin tuna, halibut, salmon, shrimp, clams & crab
Some meats like pork, beef, turkey & chicken
Some enriched foods like whole grain breads and cereals
Brown rice
Sunflower seeds
Baked beans & lentils
Mushrooms
Spinach
Oatmeal
Hard boiled eggs
Milk, yogurt, and cottage cheese
5) Iron
Iron is an important mineral in your diet that is directly linked to your red blood cells and the oxygenation of all body tissues - which can directly impact your energy levels. Iron is also key in the creation and development of immune cells as well.
The best food sources of iron can be broken into two categories –
heme and non-heme.
Heme iron is more easily absorbed by our bodies but is found in foods that may lead to chronic disease, especially if consumed in excess.
Non-heme iron is not as readily absorbed by our bodies but is found in foods that are rich in other plant nutrients that may help support overall health. Generally, consuming foods that are rich in non-heme iron with foods that are also rich in vitamin C will help your body absorb more iron from the plant-based foods.

There is some evidence that suggests that you should avoid drinking coffee and tea with meals as these may decrease the amount of iron your body absorbs.
Foods that are rich in heme iron are derived from animal sources and include:
Red meats like beef, lamb, or pork
Poultry/chicken
Eggs
Liver
Fish or shellfish like salmon, tuna, oysters, mussels, and clams
Foods that are rich in non-heme iron are plant-based and include:
Dark leafy greens/vegetables like spinach, kale, and broccoli
Beans, kidney beans, chickpeas, & lentils
Tofu
Nuts like cashews & almonds
Seeds like pumpkin, sesame, and flax
Quinoa
Oats
Whole grain breads and pastas
Fortified cereals
Black Strap Molasses
Dark chocolate
6) Vitamin E
Vitamin E is a nutrient that acts as an antioxidant in the body which helps strengthen the immune system by helping to protect your body from free radicals. (Free radicals are molecules that are produced during normal metabolic processes and when we are exposed to harmful compounds – such as those in cigarette smoke. If the level of free radicals in your body become too high, they can cause harm to healthy cells.)
Vitamin E also supports the growth of immune cells that help fight off viruses and bacteria
The foods that are highest in Vitamin E are:
Sunflower seeds & pumpkin seeds
Almonds, peanuts, Brazil nuts, cashews, & hazelnuts
Avocados
Spinach
Butternut Squash
Kiwi
Broccoli
Collard greens & Swiss chard
Olive Oil
Other cooking oils such as wheat germ oil, sunflower oil, & almond oil
Salmon & Trout
Shrimp
Mango
Blackberries
Dried cranberries
7) Vitamin A
Vitamin A is a nutrient that helps support a healthy immune system by aiding in the creation and growth of certain cells in the immune system that help to fight off bacteria and viruses.
Some foods that are a good source of Vitamin A:
Carrots
Sweet Potatoes
Butternut Squash
Tuna
Spinach
Broccoli
Bell Peppers
Cantaloupe
Pumpkin
Eggs
Some dairy foods like butter & cheese
Lettuce
Pink Grapefruit
8) Folate
Folate is a nutrient that helps to balance the body’s immune response as well as helps to support the immune function of fighting off infection.
These whole foods are a good source of folate:
Dark leafy greens & vegetables like spinach, kale, broccoli, asparagus, lettuce & brussels sprouts
Beans (like kidney beans, soybeans & chickpeas), peas & lentils
Oranges
Mangos
Peanuts
Bananas
Avocados
Eggs
Beets
Fortified foods like enriched breads, cereals & pastas
WHAT ABOUT SUPPLEMENTS?

Supplements are manufactured substances (usually in pill form) that can contain vitamins, minerals, herbs, amino acids, & enzymes (among other ingredients). The nutrients in supplements can be extracted from whole foods or made synthetically.
Getting all of the proper nutrients is very important to good health, but it is a balancing act and can be difficult to get everything you need from just your diet alone. Sometimes, vitamins and supplements can help to ensure that you are getting your daily requirements of vital minerals and nutrients - but they are intended to fill in the gaps in your diet, not take the place of healthy foods.
You should always consult with your doctor before beginning to take, increasing the dosage of, or discontinuing the use of any vitamin or supplement.
It’s important to understand that more isn’t always better, and sometimes too much of a certain nutrient can actually cause your body more harm than good. Certain vitamins and herbal supplements can also interact with other medications and either cause unpleasant side effects or increase/decrease the efficacy of the medication in a negative way.

It’s always best to discuss your concerns and goals surrounding vitamins and supplements with your doctor before you begin taking anything to make sure you are taking care of your health in the best possible way.
WHAT (IF ANYTHING) SHOULD YOU AVOID, NUTRITIONALLY?
Below are a few things that you can try to reduce or (better yet) avoid in your diet to help keep your digestive system healthy and performing at it best:

Low nutrient foods – typically foods that we consider to be “junk foods” or foods that have high fat/calorie contents, but that don’t significantly contribute to your RDAs (recommended daily allowances) of vital nutrients.
Diets that have limited variety of foods and/or are low in the consumption of fruits and vegetables – fruits and vegetables are packed with nutrients that help support a healthy immune system and your overall health. If you aren’t consuming the recommended daily servings of both, or if you’re replacing whole foods with more processed ones, there is a very good chance that you’re not getting your RDA’s of the nutrients you need to keep you healthy.
Processed foods – these are prepared/packaged foods that have been changed from their whole form (usually resulting in a change to the nutritional content that reduces the nutrients and adds fat/calories) and often have preservatives added.
Refined sugars – sugar is found naturally in many whole, healthy foods that contain other nutrients and fiber. When food manufacturers extract sugar from sugar cane or beets and process it though, it is known as refined sugar. Our bodies metabolize refined sugars differently than natural sugars, and because refined sugar is missing the fiber and nutrients in whole foods, it has little nutritional value.

Refined sugar is often used to flavor and preserve many processed foods and pre-packaged sweets and beverages. It has been linked to obesity and chronic health issues like type 2 diabetes, cancer, and cardiovascular disease – all of which can be linked to chronic inflammation in the body.
OTHER FACTORS THAT CAN AFFECT IMMUNITY
Lifestyle factors also have a lot of influence over immune health. Diet and nutrition alone can’t keep your immune system in optimal condition, and many of the choices that you make daily can have an impact on how well your immune system performs.
It might not always be easy to do, but in addition to maintaining a healthy, balanced diet, incorporating the following healthy habits into your regular routines can help boost your body's natural defenses:
Get adequate sleep - Good quality, adequate sleep is vital for many healthy body functions and many experts recommend 7 - 9 hours of sleep per night. Establishing a nightly routine, limiting exposure to blue light in the hour before you go to bed, and avoiding caffeine after 2 - 3pm in the afternoon are just a few things you can do to help improve your quality of sleep.
Stay active and get regular exercise - Staying active and establishing a regular exercise routine can help you avoid chronic diseases that can weaken your immune system. Exercise has also been proven to help improve your sleep quality.
Lower your stress - Finding healthy ways to manage stress can help balance hormones that lead to chronic inflammation in the body when their levels stay elevated for extended periods of time. Eventually, chronic inflammation can lead to illness/disease that will ultimately weaken your immune system.
Make time for self-care, relaxation, and activities that you enjoy or that bring you happiness - This one seems self explanatory, but it's very easy to get caught up in the busyness of life and to forget to take care of yourself. Making it a priority to regularly find time to relax and engage in activities that you enjoy can help support your mental health and in turn, help lower stress. It can also help you feel energized, which will support regular activity and exercise as well

Your immune system is an integral part of keeping you healthy and active, so doing what you can to support your body's natural defenses should be a priority in your healthy routine.
Consistently incorporating nutrient dense foods into your diet and practicing healthy habits are great ways to build and maintain a strong immune system that can protect you from viruses and other illnesses.
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