Immune-boosting nutrients

No one enjoys having a cold or the flu. No wonder, we’re always trying to do something to avoid them. Get shots, take anti-viral meds, take herbs or vitamins, eat chicken soup, wash your hands.

Years ago mega dose vitamin C was touted as a cure for the common cold. People took thousands of milligrams a day. Then they’d say “Oh I got a cold and I took vitamin C and I got better!” This counted as evidence that it worked.

Think about this: do you know anyone who got a cold and — years later — still has that cold?? All colds eventually go away. Even the flu goes away for most people (excepting people with compromised health).

When a virus invades your body, the immune system kicks in and fights back. It’s like an army, with different weapons and different divisions with different roles to play. But as with any army, the immune system has to be well-maintained. Your immune system depends on a steady supply of nutrients to function at an optimal level.

This isn’t to say that providing key nutrients will prevent colds or the flu. But supporting your immune system will help it work at its best. So which nutrients are most important? Truthfully all nutrients are important for immune function, but some play more central roles:

  • Water: Staying hydrated when you aren’t feeling well is important. Don’t let the cold winter weather fool you. Just because you aren’t hot and sweating doesn’t mean you don’t need to keep up with fluid intake. Winter air is drier, especially heated indoor air. Water, tea, soup, juices and coffee are all hydrating. Juices and soup have the added benefit of extra nutrients.
  • Vitamin A is important for the protective function of skin and the mucosal cells lining the respiratory and digestive system. These tissues act as barriers to bacteria and viruses. Keeping those barrier tissues healthy and strong can prevent infections from entering your system.
  • Vitamin C acts as an anti-oxidant and stimulates immune cell activity. It’s also critical for production of collagen, a key structural component of blood vessel walls and connective tissue. While there’s no evidence that mega doses boost immunity beyond the normal level, having adequate vitamin C is very important.
  • Vitamin D status is linked to risk for upper respiratory infections. Immune cells have vitamin D receptors, and the vitamin modulates immune cell function.
  • Zinc plays a key role in the development and function of immune cells. Unlike other minerals, such as iron or calcium, zinc is not stored in the body. It must be replenished from diet. Suboptimal zinc status can impact immune function by suppressing immune cell production. This is an especially critical problem for older adults who may have impaired absorption or poor intake due to dietary choices.

It’s the whole diet

Plenty of other nutrients impact immune function, from B vitamins to selenium to vitamin E and omega-3 fatty acids. One frequently over-looked problem is general malnutrition. People who are malnourished — whether from famine, severe illness, poor food intake due to dementia or aging, or eating disorders — have compromised immune function and are more prone to infections. This is one reason why the flu affects frail elderly people more severely. Giving a person like that vitamin C supplements isn’t likely to help much because all important nutrients are deficient. No one nutrient can act alone to improve immunity when a person is malnourished.

What can you do?

The time to support your immune system with good nutrition is not when you feel a cold coming on. It’s all the time. A nutrient-rich diet is your best defense. Vitamins C and A are concentrated in plant foods, such as:

  • citrus fruits
  • dark green leafy vegetables
  • berries
  • tomatoes
  • peppers
  • broccoli
  • carrots
  • melons
  • winter squash

Zinc and vitamin D are more problematic. Zinc is found in plant and animal-sourced foods, but is more concentrated and more available from meat. Vegetarians and especially vegans need to pay special attention to zinc food sources, as marginal zinc status can impact immune function. Vitamin D is not found in plant-based foods. It’s added to milk, but a person would have to consume a lot of milk everyday to meet the recommended intake. People with poor intake of these nutrients from food can consider using supplements.

Regarding Supplements

I’m not opposed to supplements. People who eat very little — elderly people with lower appetites, dieters, picky eaters — will have a hard time consuming sufficient nutrients. Where immune function is concerned, zinc in particular comes to mind. Vegans and vegetarians are likely to have poor intake and/or poor absorption of this key mineral. Unfortunately zinc status is not easily measured. Even if it were, this is not a test doctors order. Vitamin D tests are now commonplace, so it’s fairly easy to find out your status and supplement if necessary.

Immune function depends on many nutrients, so the first line of defense is food. Junky processed food diets are not going to help your immune system. And taking supplements isn’t going to fix the problems of a junky processed food diet.

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