Immunity: the best defense is a good offense.

Your good offense is built on nutrients

With coronavirus hysteria sweeping the planet, it’s a good time to revisit the role of nutrition in immune function. This is especially important for older adults, because — as with the flu — elderly people are affected more severely. That’s just accepted as the norm, but I have to wonder what exactly is it about age that puts people at higher risk? Is it just age itself? Pre-existing conditions linked to aging? Lifestyle choices? Deteriorating nutrient levels due to poor diet?

Well, we can do something about the diet/nutrition part of this equation. Nothing like being prepared in case the coronavirus, flu, common cold or some garden-variety upper respiratory infection invades your system. You can’t necessarily prevent the invasion, but you can arm your immune system to deal with it.

Stay Hydrated! Yes it’s winter, so fluid intake might not seem as critical as in hot summer weather. But dry air in heated buildings can be just as dehydrating. Don’t slack off on fluid intake. Happily it’s a great time of year for herbal tea and broth-type soups.

Vitamin C: Not too much, not too little. The official mantra is that we only “need” 75 mg/day, the amount that prevents outright deficiency. No one knows what the optimal intake is. No one has ever bothered to study what optimal even means. Researchers have been trying for decades to prove that mega doses of vitamin C have some benefit, but so far there’s no clear evidence for those claims. Some studies I’ve read suggest that 250 mg/day saturates blood levels. Intake above 250 mg/day is very quickly flushed out, so taking more is pointless.

My advice: It’s winter! High vitamin C citrus fruits are in season; eat some everyday. Grapefruit, oranges tangelos, tangerines. Then there’s the old standby: orange juice. Many of us grew up drinking a glass of OJ every morning for breakfast. Maybe that tradition should be resurrected. If you want to boost vitamin C a bit more, a supplement that added 100 mg/day should be sufficient, but don’t just rely on supplements.

Zinc: I almost can’t say enough about zinc. It’s critical for immune function (as well as a lot of other metabolic processes). Why is it especially important? Because our intake of zinc can easily crater as we age.

  • We eat less of the best zinc food sources — meats, poultry, fish. We’re told to cut those out for heart health (another one of those diet things that makes me go “Hmmmm…..”).
  • Absorption goes down due to digestive problems, medications and illness
  • Absorption goes down if you’re pushing high fiber foods, whether for gut health or as part of a more plant-centric diet.

The recommended intake of zinc is 8 mg/day. Unfortunately most zinc supplements have far more than that, anywhere from 25 – 50 or more mg/day. If you buy a supplement, you can break the tablets in half, or only take one every 2-3 days. My preference would be to take half of a 25 mg tablet every day to even out absorption. If you take a multiple, check to be sure it includes zinc. You can get too much zinc over time, which is why I don’t recommend big daily doses.

Vitamin A: Skin cells and the mucosal cells that line the respiratory tract and digestive system act as barriers to viruses and bacteria. Vitamin A plays a critical role in keeping those cells healthy and functioning properly. But supplementing with vitamin A should not be your game plan. Vitamin A is abundant in all the foods you should be eating anyway: dark leafy vegetables, citrus fruits, tomatoes, peppers, broccoli, carrots, winter squash. It’s also added to milk and many breakfast cereals. It’s in egg yolks (Oh wait, we’ve been told not to eat egg yolks for decades. Another one of those diet things that makes me go “Hmmmm….”). Multiple vitamin supplements also typically include some vitamin A. So focus on those plant foods.

Healthy Gut Microbes: A significant part of your immune system resides in your gut. There’s good evidence that helpful gut microbes are good for immune function. A diet that’s heavy on plant foods — particularly vegetables, fruit, legumes and whole grains — encourages those bacteria. Including fermented foods like yogurt or kefir (or kimchi, fermented sauerkraut, miso soup…) is a good plan, but beneficial bacteria can’t survive in a vacuum. They need to be fed, and their preference is a variety of high fiber whole plant foods.

Everything else: All nutrients will have some impact on immune function. So your overall plan should always be a really healthy diet. Supplements may have a supportive role to play, but they are not the main attraction, and supplements will not make up for a junky unbalanced diet.