The sinister pandemic culprit putting America at higher risk than Third World countries

Plus, the 5 critical infection-thwarting nutrients you’re probably not getting enough of

When I was doing fieldwork in Southeast Asia during the mid-1970s, it was already a well-known fact that nutrient deficiencies increase the risk of infections—and that inadequate nutrition was a clear problem lurking behind endemic, pandemic, and epidemic infectious diseases in Third World countries.

But here we are, nearly 50 years later, and we still hear next to nothing in the U.S. about the importance of nutrients for boosting immunity and combatting infectious disease—even after a year of the coronavirus pandemic.

Sure, some public health experts have begun dribbling out information about the importance of vitamin D and other nutrients for coronavirus symptoms. (I discussed new research on the effects of vitamins C and D on COVID-19 in the July 2020 issue of Insiders’ Cures.)

But the science about nutrition and infections has been a lot clearer, for a lot longer, than the mostly silent “experts” will admit.

And now, a new study illustrates just how far our modern public health experts need to go in order to catch up to the Third World when it comes to nutrition, dietary supplements, immune function, and infectious diseases.

Large percentages of Americans don’t get enough key nutrients

Using data from the U.S. National Health and Nutrition Examination Survey (NHANES) between 2005 and 2016, researchers analyzed the intake of nutrients critical for healthy immune function in more than 26,000 men and women.

And even using the government’s woefully inadequate recommended daily allowance (RDA), the results were sobering. (As I’ve reported before, these recommendations are determined to help avoid frank nutritional deficiency diseases—rather than the optimal amounts shown by science to help prevent the chronic and infectious diseases that plague us today.)

According to the study:

  • 45 percent of the participants had vitamin A levels below the RDA
  • 46 percent had low vitamin C levels
  • 95 percent were deficient in vitamin D
  • 84 percent had low vitamin E levels
  • 15 percent were below the RDA for zinc

And remember, the recommended amounts are totally inadequate to begin with. Plus, the researchers extrapolated this data to the entire U.S. population and concluded that the nutrient insufficiencies were so severe, they could ultimately increase the risk of infectious diseases in the population.

In addition, the researchers reported that the nutrient deficiencies were particularly notable in the people who didn’t take dietary supplements—and instead relied upon food alone for nutrients.

While a healthy, balanced diet should supply much-needed nutrients, in today’s America, that’s sadly not the case. Due to the decline in food quality and nutrient composition—not to mention the poor food choices made by too many individuals, grocery store chains, and restaurants—the risk of inadequate nutrition is real. Which is why smart supplementation is often necessary.

Key vitamins and nutrients for fighting infectious disease

A healthy immune system helps you fight off virtually every disease (not to mention infections and viruses like COVID-19). And key vitamins and nutrients can help boost and balance your immune system…

Vitamin A has long been associated with resistance to infections, and plays a key role in supporting immune cells. It also benefits the gastrointestinal microbiome, which is really “ground zero” for health—and is critical for the immune system.

Vitamin A deficiency increases risks for viral infections in both children and adults. And in a classic “Catch-22,” infections and illnesses deplete A in the blood, bumping up requirements for this nutrient. (I’ll discuss more benefits of vitamin A in next month’s issue as well—stay tuned!)

Recommended dose: Despite widespread U.S. deficiency, I don’t recommend taking vitamin A supplements. Because A is fat soluble, it has the potential of building up to high levels in your body. Fortunately, this is one instance where getting enough from food is possible, since there are plenty of foods rich in vitamin A, including meat, fish, and dairy.

Plus, yellow and orange fruits and vegetables like sweet potatoes, pumpkin, squash, carrots, and cantaloupe are loaded with certain carotenoids, which your body safely and naturally converts to vitamin A. So, be sure to add these healthy foods daily to your balanced diet.

Vitamin C has long been recognized for its ability to combat colds. Indeed, it’s required for a healthy immune response against infections. In fact, this nutrient is so essential that all animals make their own vitamin C, without needing to obtain it from the diet, except for humans and guinea pigs.

Vitamin C is water-soluble, meaning it can’t be stored in the body, so it needs to be replenished daily. Immune system cells require high amounts of vitamin C to act as antioxidant and antimicrobial agents, so it’s not surprising that C levels become rapidly depleted during colds, flus, and lung infections. In fact, research shows that the amount of vitamin C in immune cells can drop by as much as 50 percent when you have a cold—and it can take a week after recovery for your C levels to return to normal.

Recommended dose: 250 mg twice a day. If you’re fighting a cold, flu, or other infectious disease, you can safely consume up to 2,000 mg a day. One study found that taking 1,000 mg of vitamin C a day shortened the duration of colds by 6 percent, and 2,000 mg decreased duration by 21 percent.2

Vitamin D deficiency is a major public health problem worldwide, in all age groups. That’s particularly alarming when it comes to infectious diseases, because this vitamin is a central regulator of the body’s defenses against infections. Low levels of D are associated with increased risks of respiratory infections, ear infections, urinary tract infections, hepatitis, and other infections.

For most people living in the northern hemisphere, the body’s ability to make D from sunshine is nonexistent during winter—right when cold and flu season hits. A dramatic example occurred during the 1918-19 Spanish flu pandemic, when there were higher death rates in populations with less sunlight exposure. This was even before vitamin D was discovered during the 1920s. And now, in the age of coronavirus, new research links low vitamin D levels to a higher risk of severe complications and death.

Recommended dose: Ask your doctor for a vitamin D blood test. Optimal levels are between 50 and 75 nmol/L. To help reach and/or maintain these levels, I recommend supplementing with 10,000 IU per day—especially during winter. Just remember to get your levels tested by your doctor once every six months.

Vitamin E enhances immune response by boosting white blood cell activity. It also prevents oxidative damage to cellular membranes, preserving the function of immune cells.

Vitamin E is especially crucial for older people. Several studies show it can reduce the incidence and severity of respiratory infections in people whose immune systems may be compromised due to age.

Recommended dose: 50 mg per day. You’ll want to look for a supplement that ideally contains the eight active compounds that make up vitamin E—four tocopherols (alpha, beta, delta, and gamma) and four tocotrienols (also called alpha, beta, delta, and gamma).

But again, following a healthy, balanced diet is key—or you may need higher amounts.

Zinc supports the immune system through a number of different functions. Just a mild deficiency in zinc can increase the risk and severity of viral infections. And research shows that people over the age of 60 tend to have lower zinc blood levels than younger adults.

Without sufficient zinc levels, regulation of the immune system can run out of control, resulting in the hyper-inflammatory states that damage lungs and other organs (as can be seen in serious cases of coronavirus, which is why zinc is so important in treating this particular infection).

Recommended dose: Up to 100 mg of zinc acetate lozenges per day. One study found that a daily combination of 10 to 30 mg of zinc with 1,000 mg of vitamin C shortened the duration of respiratory tract infections, including the common cold.3

Of course, there’s one eye-opening conclusion from this major new research:

Most people today need to take dietary supplements to protect themselves against infectious diseases. And smart supplementation is still necessary to complement a healthy, balanced diet.

Otherwise, mainstream medicine in the U.S. will sadly continue to lag behind Third World countries when it comes to understanding and controlling infectious diseases in the population.


1“Inadequacy of immune health nutrients: intakes in US adults, the 2005-2016 NHANES.” Nutrients. 2020 Jun 10;12(6):E1735.

2“Vitamin C supplementation and common cold symptoms: factors affecting the magnitude of the benefit.” Med Hypotheses. 1999 Feb;52(2):171-8.

3“A combination of high-dose vitamin C plus zinc for the common cold.” J Int Med Res. 2012;40(1):28-42.