In the modern diet full of take-out meals and process foods most of us are not getting enough of these critical nutrients – vitamins C, E, A, D, and B9 (Folate). Deficiencies in these vitamins leave millions of Americans open to weakening immunity and susceptible infections like the coronavirus.  According to a study based on the National Health and Nutrition Examination Survey, 31% of Americans are at risk of at least one of the above vitamin deficiencies.

Since all five of these essential vitamins support proper immune function, not getting enough of them can dramatically weaken one’s immune system.

What Happens when you don’t get enough?

Vitamin C: Also known as ascorbic acid; it is required for the synthesis and repair of many tissues like skin, bone, and cartilage. It is essential for the formation of cartilage which is the building block of hair, bone, and nails. Being a strong antioxidant, vitamin C also plays a key role in the immune system and helps to kill external pathogens in macrophages. Chronic deficiency of vitamin C results in a weaker immune system and a disease named as scurvy. Lack of vitamin C can manifest as:

  • Impaired immunity
  • Rough Dry skin
  • Corkscrew shaped hair
  • Bright red hair follicles
  • Spoon shaped nails with lines
  • Frequent and prolonged infections
  • Slow-healing wounds
  • Easy bruising and tooth loss
  • Swollen painful joints
  • Weaker bones


Vitamin E: It is another essential vitamin with potent antioxidant qualities. Vitamin E is needed for the smooth functioning of the immune system and protection against free radicals. Though rare, vitamin E deficiencies are linked with:

  • The frequent onset of infections due to inhibition of immune cells
  • Numbness and tingling
  • Muscle weakness
  • Walking difficulties
  • Adverse vision changes
  • Lack of coordination


Vitamin A: It is also known as retinol and its deficiency is quite common in developing countries. It is required in adequate quantities for healthier skin, good vision, and a stronger immune system. Vitamin A deficiency can culminate in:

  • Night blindness (the earliest sign of vitamin A deficiency)
  • Thickening and drying of conjunctiva
  • Infertility
  • Delayed growth
  • Frequent throat and chest infections


Vitamin D: Vitamin D is required for about 200 enzymatic pathways and bones get most of its benefits by getting thick and stronger. It acts like hormones and interacts with immune cells directly through its receptors mediating their functions. Vitamin D deficiency can lead to:

  • Frequent infections and sickness
  • A consistent feeling of being tired
  • Bone and muscle pains
  • Depression
  • Bone and hair loss


Vitamin B9 (Folate): Folate deficiency causes anemia (lack of red blood cells) as cells fail to mature to their optimum levels. Vitamin B9 also stimulates the production of white blood cells while deficient levels fail to perform this role efficiently. Major signs of folate deficiency include:

  • Tiredness and easy fatigability
  • Irritation
  • Palpitations
  • Shortness of breath
  • Headache and difficulty concentrating


Best Whole Food Source of Immune Supporting Vitamins:

Vitamin C: Rich sources of vitamin C include citrus fruits like oranges, lemon, kiwi, grapefruit, strawberries, guava, papaya, bell pepper, broccoli, tomato, and kale.

Vitamin E: Sunflower seeds, almonds, peanuts, avocados, spinach and vegetable oils (soybean oil, corn oil) are good food sources of vitamin E.

Vitamin A: Best food sources of vitamin A are cod liver oil, eggs, beef liver, fortified skim milk, carrots, sweet potato, spinach, and broccoli.

Vitamin D: Vitamin D is synthesized in the skin in the presence of Sunlight. Good food sources of vitamin D are tuna, salmon, beef liver, cheese, egg yolks, and dairy products.

Vitamin B9 (Folate): Best whole food sources of folate include beans, citrus fruits, leafy vegetables, whole grains, lettuce, beets, asparagus, and cauliflower.


According to a study based on the National Health and Nutrition Examination Survey, 31% of Americans are at risk of at least one major vitamin deficiencies; including vitamins C, E, A, D, and B9 (Folate). To avoid an impaired immune system eating a plentiful amount of healthy whole foods is the key. Consume the given food sources in a well-balanced diet and enjoy the perks of a healthy life.



Vitamin C Deficiency (Scurvy) – StatPearls – NCBI Bookshelf

Vitamin E – Consumer

Vitamin D Deficiency: MedlinePlus

What Is Vitamin A Deficiency? – American Academy of Ophthalmology

Vitamin B9 (folate) deficiency

The best foods for vitamins and minerals – Harvard Health


Chef Shedric

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