Boosting the Immune System

Use Selected Supplements:

I think the two most important supplements for prevention are Vitamin D and Zinc :

Vitamin D 2-5000 iu daily

Especially in the winter months

In one study of different groups of people followed for one year,  the group that took no vitamin D there were 31 attacks of flu and colds whereas in the group that took 2000iu vitamin D there was only one episode.

Another study looked at children under one years of age hospitalised with RSV infection. They found 17.5% (of 125 children) developed life-threatening disease (LFD). This means they needed ITU and ventilatory support.

You might wonder which kids developed life-threatening disease? Was it those with the highest viral load? No, this made no difference. However, those who developed life-threatening disease had significantly lower serum Vitamin D (average 45nmol/l) whereas those who didn’t have LFD had a much higher average Vitamin D of 79nmol/l. In fact, 59% of infants with LFD had a Vitamin D levels below 50nmol/l.

The authors say this provides additional evidence for the development of preventative strategies. J Infect Dis, 2022 Feb 1;jiac033. doi: 10.1093/infdis/jiac033. In other words Vitamin D is an essential preventative strategy.

Doses of up to 10,000 iu are safe (exposure to sunlight in a swimming costume on a hot day for ½ hour can produce 10-20,000 iu of Vitamin D)

For adults take 5000 iu daily for 2 weeks and then 2000iu daily (it takes 2 weeks for levels in the blood to build up) . For children use 2000 iu daily (1000iu for children under 1). In summer you may not need any but if you are indoors a lot (most people) take 1000 iu daily in the evening (so you don’t lose the benefit of the sunshine). Double the dose during any infection.

Apart from vitamin D, sunlight itself stimulates the thymus gland, which is crucial for immunity.


Zinc is crucial to both the humoral and cell-mediated immunity and has specific anti-viral effects. IThe immune hormone thymosin contains zinc.

In one study by Prasad in 2007, a group of people aged 55-87 were given either zinc 45mg daily or placebo for one year. Those given the placebo had three times as many infections and needed six times as many antibiotics.

  Use zinc 30-50mg daily, best taken in the evening. After 1 -2 months reduce to 15mg daily (use this dose for children)

If possible add:

EPA Fish oil 1000-2000mg daily

Vitamin C 2-4 grams daily (not at same time as zinc)

Multivitamin/Multimineral complex

Other Nutrients

        Although the above nutrients will help resolve many problems, there are other crucial nutrients for immunity. Selenium stops viral replication so a deficiency could cause problems. It is important in chronic viral infection and boosts neutrophil numbers and natural killer cells.

        Essential fats, (see Fats: the Good and the Bad leaflet) are important in infections and critical in post-viral illnesses (which seem to be getting more common).

        The body has staggering abilities to combat infection, providing it has the right building blocks. It can produce 200,000 immune cells in one minute.

Immunity and the Gut

(85% of our immunity comes from our gut).

Take these 2 studies: one found taking a daily probiotic (bifidobacterium) in children aged between 3 and 6 reduced coughs and colds and the second, a meta-analysis of 8 studies, showed a daily probiotic (with lactobacillus and/or bifidobacterium) reduced respiratory infections in adults and children.

However I think if you take a probiotic and don’t feed the bugs you are likely to be wasting your money. You need to feed the good bugs (with vegetables, low-sugar fruits, nuts, seeds) and stop the sugar and processed foods (and antibiotics) which either damage the good bugs or feed the harmful bugs.

During Infections: Use High-Dose Vitamin C

Take Vitamin C 1-2 grams every 2-4 hrs (up to 80-90% of bowel tolerance where the stools become slightly loose and then reduce slightly. Usually this happens at 10-15 grams vitamin C but more in a severe infection). See Vitamin C leaflet for more details.

This is a highly effective way of treating both bacterial and viral infections -even though few doctors are aware of the research: see Vitamin C leaflet for more information. HOWEVER IT HAS TO BE HIGH DOSE TO WORK.

After this 2 to 4 grams daily

The best way to take high dose Vitamin C is to use Vitamin C powder. However it has a strong taste. Chewable tablets (500mg or 1 gram) are an option though these supplements are a poorer quality. They are a good option for children.

Dr Robert Cathcart said he has not seen any flu that has not been cured or markedly ameliorated by massive doses of Vitamin C. The Vitamin C leaflet gives evidence that it is highly effective in sepsis.

Beta-glucans, which are derived from the cell wall of fungi, yeast and grains, can help during infections and to protect against infections. Use from 70 -150mg daily.

Taking Echinacea can help or the more expensive but probably more potent Olive leaf extract.


Dietary Considerations

Cut down on sugar. Sugar can double the number of bacteria in 20 minutes. It also reduces the body’s ability to engulf bacteria and viruses by about 50% and this effect can last 5 hours. It also competes with vitamin C. Anyone with an infection or recurrent infections needs to be on a diet which is very low in sugar and refined carbohydrates (bread, cereal, white rice, pasta) until they have fully recovered. Children’s food is particularly high in sugar (cereals, soft drinks, fruit juice, yoghurts and confectionery) and reducing these makes a real difference

Increase fruit, vegetables, nuts & seeds

(one group of pre-school children who ate one kiwi fruit a day reduced the number of infections by nearly half)

Increase daylight/sunlight exposure – known to boost immunity

Increase Exercise (but not during an infection). Exercise makes the lymphatic system more efficient.

Another Tip

        Here’s a study that’s been buried in the medical journals since 1944. 112 patients with cold were given cod-liver oil (containing 150,000 units Vitamin A and 15,000 units Vitamin D) on the first day and a third of this on the second day. If symptoms remained two-thirds of the original dose was given on the third day. After 24 hrs 30% were symptom free and 52% almost symptom-free. That’s 82% virtually cured in 24 hours. No adverse effects were seen. I understand this regime has been used in successfully in nutritional clinics since then.

        Most cod-liver oil these days has much lower levels of Vitamin A or D so usually extra supplements of these would be needed to reach these levels today.

 NOTE: this amount of vitamin A is not suitable for pregnant women.

Thymus Tapping

The key organ controlling immunity is the thymus gland which lies under the sternum (breastbone). Thymus tapping involves tapping in the middle of the sternum which stimulates the gland. Tap with four fingers, enough to cause a gentle vibration. Try 10 taps daily as a preventative, going up to 60 three times daily during infections. No studies exist on this but it costs nothing and is worth trying.