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Immunity, aging and nutrition

Immunity, aging and nutrition

Immunity has been a hot topic for almost 2 years, for obvious reasons. Strangely, the link between immune function and nutrition is not front-and-center. It should be. Without nutrients, you don’t have a functioning immune system.

To make matters worse, immune function deteriorates as we age. The reasons for this are likely numerous, but nutrition is certainly high on the list of potential contributing factors. Why?

Nutrient intake decreases because food intake decreases.

  • Appetite is reduced
  • Taste preferences change
  • Chewing may be a problem with some foods
  • Cost and shopping/cooking logistics limit food choices
  • Medical problems impact food intake: dementia, diabetes, depression, heart disease, etc.

Absorption of nutrients decreases.

  • Less stomach acid production -> digestive process is disrupted
  • intestinal function deteriorates
  • medications interfere with nutrients
  • chronic intestinal infections disrupt the gut lining

As I learned from a recent webinar on immunity and aging, many elderly people maintain well-functioning immune systems well into their 80s. Others have steep drops in immune response after age 60. What makes the difference? Luck? Lifestyle? If better nutrient status can improve immune function, why not make an effort?

Here’s a brief description of immune system basics:

Immunity is a 4-step system:

  1. Barriers. Mother Nature equipped us with a variety of barriers to keep pathogens out: skin, mucous membranes, intestinal lining, lung cells, saliva, tears, gastric acid.
  2. Innate Immune Response. If a pathogen gets past the many barriers, your body mobilizes a variety of immune cells and chemical mediators to fight back. Inflammation is part of this process.
  3. Adaptive Immunity. Specialized cells learn to recognize the pathogen. Some of these cells produce antibodies that specifically target the pathogen. Vaccination stimulates this type of response.
  4. Memory. After the pathogen is eliminated, the specialized cells of the Adaptive response store the memory of that pathogen. If it shows up again, antibody production is ramped up to fight it again. This is the goal of vaccination: to create that pathogen memory.

All of these steps depend on an adequate supply of nutrients to function. It’s even more important during an infection, when nutrient demand increases. Which nutrients are critical? Over the past 2 years, we’ve heard a lot about vitamin D; low blood levels are linked to severe Covid infections. But many other nutrients are critically important for immune function, too:

  • vitamin E
  • vitamin A
  • vitamin C
  • vitamin D
  • zinc
  • B12
  • B6
  • folate
  • selenium
  • omega-3 fats
  • iron
  • certain amino acids (from protein)

There’s increasing evidence that other food components are also important for the immune system: phytochemicals from plant foods, prebiotics and probiotics.

No coincidence, intake of most (if not all) of these nutrients falls off as we age due to all the reasons listed above. So just when you need your immune system to be at its best, the supply of nutritional building blocks decreases. It doesn’t have to be that way. You can make food choices to boost intake of all those key nutrients.

Immune-Critical Diet

What should you eat to support your immune system? It’s not rocket science. The best diet is (wait for it..) sometimes vegetarian. Meaning, plenty of vegetables, whole grain foods, nuts, fruit, healthy fats and some animal products. The meat, eggs and fish provide zinc, B12, iron, selenium, protein. High fat fish for omega-3 fats. Dairy foods for protein, B12, zinc, probiotics, vitamin D and A. Plant foods (vegetables, fruit, grains, nuts and healthy oils) for phytochemicals, prebiotics, vitamins A, E, C, folate, B6, selenium, zinc.


Should you add a supplement? Consider this conclusion from a recent review of the topic published in January 2020, just before we all went into lockdown:

Clearly, micronutrients are an integral part of the immune system, and the body needs optimal levels for effective immune function. …… micronutrient deficiencies can adversely affect the immune system and predispose individuals to infections. …. marginal deficiencies are also associated with increased risk of infections. ….. a gap exists between dietary intakes and levels for optimal immune function, providing a rationale to supplement the diet with micronutrients to help support the immune system and reduce the risk of infection.

A Review of Micronutrients and the Immune System

The researchers who spoke at the webinar made the same point, particularly regarding older adults. As the Covid pandemic showed, elderly people with compromised immune systems were at high risk for severe infection. This increased risk is seen with seasonal flu, pneumonia and infections of the digestive tract.

A word of caution: excess intake of nutrients doesn’t improve immune function. In some cases, an excess could actually interfere. Supplements are NOT a replacement for a good diet. The point of supplements is to improve your nutrient intake from food, not replace it.

I’m not a fan of any of the so-called immune-boosting/supporting supplement formulas. In many cases, the formula don’t include any actual nutrients. In other cases, the doses are either excessive or trivial. If you want to boost your intake of these nutrients, a multi vitamin/mineral formula for 50+ is a reasonable choice. I’m not in the business of promoting particular products. Well-known national supplement brands that are easily available at the local grocery or chain store are fine. Frequently the generic house brand is equivalent. Compare labels if in doubt.

Making Your Choices

If your diet is pristine, loaded with vegetables, whole grains and fruit everyday, with reasonable portions of dairy foods, eggs or meat, then you might be fine without supplements.

Aging isn’t a choice. Making good choices as you age is a choice. Food choices are one aspect of immune function you can control. Here’s a list of nutrient-rich foods that support the immune system:

  • citrus fruit and 100% juices: oranges, grapefruit, tangerines
  • dark leafy green vegetables: spinach, kale, chard, arugula, dark lettuces,…
  • high fat fish: salmon, sardines, herring, mackerel
  • foods with live cultures: yogurt, kefir, kombucha, kimchi
  • whole grain cereals like oatmeal and foods made with whole grains
  • various fruits and vegetables that contain certain flavonoids: apples, broccoli, onions, fresh tomatoes, blueberries, mushrooms
  • nuts and healthy oils like olive, avocado and canola

Foods that do not support immune function? Junk food and highly processed food in general. Sorry, but ice cream, potato chips, donuts, sports drinks and the like aren’t on the immune-supporting list.