Vitamin C and Cortisol: Optimizing the Immune Response

Your immune system works hard to fight germs and keep your body healthy. Vitamin C plays an important part in keeping stress hormones like cortisol at bay. Taking good care of yourself and eating enough vitamin C-containing foods will help keep your immune system strong.

Key takeaways:

Your immune system is a complex network made up of different organs, cells, lymph nodes, glands, and tissues. Its primary job is to keep you healthy and free from germs. When your immune system is working properly, it activates and mobilizes when a germ enters your body. A healthy immune system can tell the difference between normal cells and unhealthy cells.

To keep your immune system strong, there are steps you can take. Vitamin C plays an important part in immune system function. Cortisol, a stress hormone, can be reduced if your diet contains plenty of vitamin C. Otherwise, it's useful to take one of the best supplements to control and reduce cortisol levels.

What is vitamin C?

Vitamin C, also known as L-ascorbic acid, is a water-soluble vitamin found naturally in many fruits and vegetables. While most animals synthesize their own vitamin C, humans do not, so we must get it from the foods we eat. When you eat vitamin C-containing foods, your body stores a small amount in white blood cells, the adrenal glands, and other areas.

Benefits of Vitamin C

Vitamin C is vital to your health, and you cannot live without it. There are many different bodily processes that require vitamin C. These include:

  • Collagen formation. Collagen is an important component of connective tissue.
  • Wound healing. Vitamin C aids in all aspects of the wound healing process.
  • Neurotransmitter production. Vitamin C aids in producing neurotransmitters that affect mood, such as dopamine, serotonin, epinephrine.
  • Iron absorption. Iron is a key mineral in maintaining health.
  • Protein metabolization. Protein is the building block for all body tissues.
  • Free radical protection. Vitamin C acts as an antioxidant and helps slow down aging and the progression of certain diseases.
  • Immune health. Vitamin C plays an important role in immune function.

Vitamin C sources

Vitamin C is found in many types of foods and in various supplements to support the immune system. The best sources include:

  • Red and green bell peppers;
  • Broccoli;
  • Oranges and other citrus fruits;
  • Strawberries;
  • Brussels sprouts;
  • Cantaloupe;
  • Kiwifruit;
  • Potatoes.

The Food and Nutrition Board, a part of the Institute of Medicine, lists the recommended intake of vitamin C for people of all ages.

As we age, our need for vitamin C increases. People who smoke need extra vitamin C to combat the increased oxidative stress that cigarette smoke has on the body. It’s difficult to eat too much vitamin C as any extra is excreted through the urine.

Also, vitamin C can be destroyed by heat, so it’s best to consume many of these foods raw in order to get enough vitamin C. Ascorbic acid is water-soluble, so cooking food with vitamin C can reduce the number of vitamins in the food. Five servings of fruits and vegetables a day will provide you with more than adequate amounts of vitamin C for good health.

Vitamin C & immune response to stress

Vitamin C plays an important role in your immune system’s response to stress. In particular, it stimulates the production of white blood cells, which fight infection, and liver enzymes, which play an important part in keeping your body free of toxins. Low levels of vitamin C can weaken your immune system.

When we are stressed, something called the HPA axis is activated. This refers to the combined work of several glands: the hypothalamus, the pituitary, and the adrenal glands. These glands release different hormones, the most familiar being cortisol. Cortisol is the primary stress hormone and is associated with what is often called the “fight or flight” response.

Cortisol is released from the adrenal glands that sit atop the kidneys. Cortisol is a steroid hormone that has many important roles in the body, including regulating metabolism, blood sugar, and blood pressure, and it helps control the sleep-wake cycle. But when stress happens, large amounts of cortisol are released into the blood and cause damage.

Vitamin C is used by the adrenal glands when it produces cortisol. When you experience acute stress, like narrowly avoiding a car accident, your adrenal glands dump large amounts of cortisol into your blood, which uses up your stored vitamin C quickly. Low levels of vitamin C in the body are a stress as well, which starts the cycle all over again.

With acute stress, your body releases large amounts of cortisol and other stress hormones, and then the levels go back to normal. It is different when you experience day-to-day stress. With chronic stress, the HPA axis is constantly activated, and cortisol is always being released in large amounts. Chronic stress can be things like living through a pandemic, having a stressful job, or dealing with a chronic illness. Chronic stress causes damage to the body over time.

How to optimize your immune system

Many of us experience chronic stress, which weakens the immune system. A robust immune system can fight infections like the cold or flu and even mount an attack against cancer.

Ingesting sufficient vitamin C by eating fresh fruits and vegetables and supplementing, if needed, can counterbalance the high level of cortisol you have in your body when you experience chronic stress. Studies suggest that vitamin C can reduce stress and improve the immune system by putting the brakes on the release of cortisol.

Here are some steps you can take to optimize your immune system:

  1. Eat a variety of fruits and vegetables. This is a good way to ensure you're getting enough vitamin C.
  2. Exercise. Regular physical activity can help you in many ways, including helping you sleep better, which will strengthen your immune system.
  3. Quit smoking. Cigarette smoking increases oxidative stress on the body, weakening the immune system.
  4. Practice good hygiene. Washing your hands regularly with hot water and soap can reduce the number of germs you ingest, which will keep your immune system healthy.
  5. Reduce stress. If possible, take steps to reduce your exposure to stressful situations.

Vitamin C is important for the health of our immune systems. It keeps the stress hormones like cortisol in check and acts as an antioxidant in the body. Vitamin C helps strengthen disease-fighting white blood cells. Taking steps to optimize your immune system, like eating well, exercising, quitting smoking, and getting enough sleep, will help vitamin C do its job. We can’t always remove all chronic stressors in our lives, but taking any step you can to reduce stress and keep sufficient vitamin C levels in your body is a step in the right direction.

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