Vitamin D, Covid, Milk Supply, Immunity

Vitamin D, Covid, Milk Supply, Immunity

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Immune-Boosting Supplements for Covid – and also for Milk Production

Since the start of the pandemic in early 2020, the doctors I follow[i] have recommended four basic supplements to advance the immune system’s first line of defense against Covid-19. These are:

Quercetin, Zinc, Vitamin D and Vitamin C.

I have been taking them and I hope you have been, too.

I find it interesting that Quercetin, Zinc, and Vitamin D all support pregnancy and good lactation. As a “side-effect,” they boost the immune system specifically against viruses.

(Vitamin C is of course also important and useful, but for mothers with IGT it may best be reduced during early lactation for reasons I explain in Mother Food.)

In this post, we’ll look at vitamin D. I will write about the other supplements in following posts. Sign up to my newsletter to be notified of new articles. 

Vitamin D

Vitamin D is called an “immunomodulator” because it enables the immune system to modulate, that is, to react quickly, flexibly and intelligently against pathogens.

At the beginning of an infection, a quick and adept response gives the immune system an edge over the disease.

People with good levels of vitamin D have fewer and less severe viral and upper respiratory diseases.

People with low blood levels of vitamin D are more prone to viral and respiratory diseases, but also to fatigue, chronic infectious and autoimmune diseases, gum disease, diabetes, brain-fog, depression and other mood disorders. In short, people with low vitamin D are immunocompromised.

Vitamin D is also involved in bone strength and in regulating insulin sensitivity–two important factors for women.

Who is at risk? 

Vitamin D is obtained from skin exposure to the sun and from specific dietary sources.

People who live in the northerly climates with cloudy skies and reduced sun exposure are at risk for low D.

People who live mostly indoors, or who wear sunscreen when in the sun, are at higher risk.

People with melanin-rich skin are at higher risk, as the melanin slows the absorption of sunrays and slows the production of D.

People whose diets exclude animal sources of Vitamin D, especially eggs, animal fat, dairy cream and fatty fish are at risk because these are our food sources of vitamin D.

As well, people with chronic health conditions or who are older can have a harder time absorbing Vitamin D from food, or converting sun exposure into vitamin D.

Supplementing Vitamin D

Even though Vitamin D supplements are inexpensive and easily available, some people find it difficult to increase their blood levels of this vitamin. Here’s why:

  1. Overweight and obese persons require more time because vitamin D must first fill up the fat cells before it rises in the blood. It can take weeks, months and sometimes years of consistent supplementation.
  2. Doctors tend to under-dose vitamin D. Consistent high doses may be needed to move the dial and increase the levels.
  3. People respond differently to forms of Vitamin D3 supplementation. Combinations of different brands and types may be needed.
  4. Vitamin D should be taken with magnesium[ii] and vitamin K to prevent the displacement of calcium.

As you can see, recommending that people supplement with high doses of Vitamin D is not that simple, and considering that high dosage, multiple brands and also added magnesium and vitamin K are needed, it is not as easily affordable for low-income families.

The current definitions of levels of vitamin D are:

Deficient: Less than or equal to 10 ng/ml (25 nmol/L)

Insufficient: Between 10 ng/ml and 20 ng/ml (25 to 50 nmol/L)

Sufficient: More than 20 ng/ml (50 nmol/L)

Please consult with your doctor to learn your present level of vitamin D, and get started with your personal program. 


Vitamin D Supplementing Tips

In my case, several attempts to increase my vitamin D blood levels failed because the doctor’s recommended dosage was not high enough and I was not told to also supplement with Vitamin K and magnesium.

Through experience and in conversation with other patients, I found that the best way to take vitamin D is to alternate brands and types, and to take it in the morning together with a beverage or meal that includes some fat or cream, to ensure that this fat-soluble vitamin is properly digested.

I aim for about 10,000 iu a day, a dose that is considered safe for most people.[iii]

Over the last year, my vitamin D levels rose from 20 (deficient) to 60 nmol/L (sufficient).

I feel significantly safer now with higher levels of Vitamin D, especially as I also supplement with Vitamin K and magnesium.

While scientists race to produce new vaccines for new variants, we can be actively involved in keeping our immune system the most resilient that it can be.

Vitamin D and Covid

We know that persons with adequate blood levels of vitamin D rarely develop severe covid-19, and that persons with a blood level of above 40 have better outcomes.[iv]

One might ask why no public health measure has been enacted that would roll out high-dose vitamin D supplementation to those who need it most, together with vitamin K and magnesium.

The answer seems to be that our medical system is designed to respond to symptoms, to step in only after a disease is already in progress. It is not designed to be preventative, that is, to reduce susceptibility to disease by building up a person’s resiliency.

Vaccinations are supposed to act preventatively. But in fact, they only target a specific disease and do not increase the overall immune resiliency or health of a population.

Low Milk Supply Mothers

Mothers with true low milk supply are likely to have one or more of the following health issues: we are overweight or obese, have insulin resistance or diabetes, have some degree of PCOS,[v] and may have chronic health conditions.

I recall a mother in our online group MOBI who “tried everything” to build her supply without success, but finally had a significant boost when her doctor gave her a mega-boost of Vitamin D: 40,000 iu, all at once.

Her supply increase might relate to the role of vitamin D in lactation: it surely facilitates the action of calcium, an important mineral for milk production.

While do not have concrete research on the effect of vitamin D supplementation on milk production, many of us here in lactation-world believe the correspondence is significant.

Moreover, because vitamin D supplementation has shown benefit in stopping the progression from pre-diabetes to diabetes, its use in insulin resistance is indicated.[vi]

Low Milk Supply Mothers and COVID

Clearly, low milk supply is linked to many health conditions that are acknowledged risk factors for Covid, from insulin resistance and prediabetes to obesity, and autoimmune conditions. As these conditions are also linked to low Vitamin D, supplementation of vitamin D3 in combination with magnesium and Vitamin K may be useful in building a mother’s immune resiliency.

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[i] I will not name the doctors here, as professional medical persons may be deplatformed for suggesting that it is possible to increase immunity or build resistance to this disease, in spite of the exhaustive clinical practice showing otherwise.

[ii] Uwitonze, A.M.; Razzaque, M.S. Role of Magnesium in Vitamin D Activation and Function. J. Am. Osteopath Assoc. 2018, 118, 181–189.


[iii] Krul-Poel YHM, Koenders PP, Steegers-Theunissen RP, ten Boekel E, Wee MMt, et al. (2018) Vitamin D and metabolic disturbances in polycystic ovary syndrome (PCOS): A cross-sectional study. PLOS ONE 13(12): e0204748.


[iv] Bleizgys, A. Vitamin D and COVID‐19: It is time to act. Int J Clin Pract. 2021; 75:e13748.

[v] Krul-Poel YHM, Koenders PP, Steegers-Theunissen RP, ten Boekel E, Wee MMt, et al. (2018) Vitamin D and metabolic disturbances in polycystic ovary syndrome (PCOS): A cross-sectional study. PLOS ONE 13(12): e0204748.


[vi] Mahtab Niroomand, Akbar Fotouhi, Navid Irannejad, Farhad Hosseinpanah, Does high-dose vitamin D supplementation impact insulin resistance and risk of development of diabetes in patients with pre-diabetes? A double-blind randomized clinical trial, Diabetes Research and Clinical Practice, Volume 148, 2019, Pages 1-9, ISSN 0168-8227,