Nutrition 101 – Vitamin D

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Vitamin D is probably most well known for being a vitamin that our bodies can produce from sunlight. But despite it being essentially “free” for us to consume, many people are actually deficient! Clouds, pollution, window glass, and dark skin pigmentation all decrease the amount of vitamin D our bodies can make from sunlight. Plus, depending on the intensity of the sun, for a lot of people there are many months in the year where it just isn’t strong enough for vitamin D production to take place. 

This vitamin tends to have more in common with hormones and is closely related to estrogen and cortisone. It’s actually a cholesterol-like substance and requires practically full-body participation in order to be manufactured and used. The process starts in your skin cells as the UVB light from the sun interacts with the compound 7-dehydrochlesterol to form cholecalciferol. This new compound then heads to the liver or kidneys to be converted to 25-hydroxycholecalciferol (not the most active form) and then to the fully active form 125-dihydroxycholecalciferol by the kidneys. This is the form that we common call vitamin D3. 

The vitamin D that we consume in food or via supplements is absorbed through the intestinal wall. It’s a fat soluble vitamin, so it is absorbed along with fats and with the aid of the bile produced by our liver. The vitamin D is mainly taken to the liver for storage, but it can also be stored in our skin, brain, or bones. 

Benefits of Vitamin D

Vitamin D has a strong relationship with some of the other nutrients, especially calcium. It helps regulate calcium metabolism and aids in its absorption in the gut. It also, when needed, helps decrease the excretion of calcium by the kidneys. 

It promotes the reabsorption of calcium and phosphorus into the bones, specifically the teeth, and helps maintain a healthy blood level of calcium (and therefore pH level of the blood).  Even with adequate calcium and phosphorus intake, if there is not sufficient vitamin D levels, then these minerals will not be used effectively. 

Calcium, magnesium, and vitamin D together are very supportive of heart health and the nervous system and help prevent against osteoporosis, tooth decay, and gum disease.

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Depletion, Deficiency, and Toxicity

As mentioned, vitamin D production by the skin can be inhibited by pollution, clouds, the distance of the sun from the Earth, clothing, window glass, dark skin pigmentation, and sunscreen, and our bodies ability to produce vitamin D decreases naturally as we age.

A severe vitamin D deficiency disease is known as rickets which results in symptoms mainly affecting bone structure and development such as 

  • Soft skull bones and bone fragility

  • A bowing of the legs

  • Spinal curvature

  • Increased size of joints

  • Muscle spasms

  • Poor teeth structure

  • Near sightedness

  • Loss of hearing

Vitamin D is potentially one of the vitamins where it is the most easy to consume a toxic dosage. This can easily occur with either a too large supplementation dosage, and/or in combination with excessive sun exposure. It’s possible that some symptoms of sun-poisoning can be attributed to vitamin D toxicity. 

 An excessive intake of Vitamin D can show up in symptoms like:

  • Excessive thirst

  • Diarrhea

  • Nausea

  • Weakness & headaches

  • Increased levels of calcium and phosphorus in the urine

Dietary Sources of Vitamin D

Unfortunately, there aren’t a lot of foods that have vitamin D. The easiest way to eat your requirements is through seafood, but there are also a few other choices as well. Not mentioned on the list, but to be considered, is that a lot of processed foods (milk from the grocery store, cereals, and even orange juice) have been fortified with vitamin D, which would count towards your required needs. There are the main food sources of vitamin D:

  • Mushrooms

  • Milk

  • Egg yolks

  • Butter

  • Liver

  • Oily fish (mackerel, salmon, herring, sardines)

  • Cod liver oil

Sensible sun exposure will also allow your body to produce some vitamin D, of course it is hard to gauge how much is being produced at any time. In general, aim for around 10-15 minutes of sun on exposed arms, legs, or abdomen a day (the skin shouldn’t begin turning pink – if it does you’ve gone for too long!). If you have sensitive skin, start slowly with only a couple minutes and gradually increase. 

The general aim for intake of vitamin D (through food and supplementation combined) is 600 IU per day, going up to 800IU for people over 70 years of age, and staying below a maximum intake of 4000 IU per day. (1)


Got some questions still on vitamin D? Ask below in the comments!

Nutrition 101 – Vitamin C

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When most of us think about vitamin C, we tend to think about oranges and orange juice! It’s probably one of the most commonly known vitamins, and it’s a very important nutrient for our body, one that we can only obtain through our diet. It’s commonly found in fruits and vegetables, but since vitamin C tends to be found in the watery parts of these plants, it can be lost during cooking. Therefore, for the highest vitamin C content, it is best to eat the raw, uncooked forms.  

Most of the vitamin C we ingest is absorbed by the intestines. Then it is used by the body within about 2 hours and is already out of our blood stream within 3-4 hours. However, our body will use the vitamin C much more rapidly during certain circumstances such as during elevated stress, alcohol use, smoking, fever or viral illnesses, antibiotics, pain medication, or cortisone use, or exposure to environmental toxins or heavy metals. Vitamin C is one of the most commonly supplemented vitamins.

Benefits of Vitamin C

The most common association for vitamin C is with immune support and drinking orange juice while sick. And indeed vitamin C helps stimulate our immune system, it can help activate certain white blood cells and can help with inflammatory problems and treating viral, bacterial, and fungal infections. 

But beyond its immune function, vitamin C also plays a role many other processes:

  • Formation and maintenance of collagen, the most abundant protein in our body (read more about collagen here), which also means it helps us heal from injuries

  • Aids in our cholesterol metabolism (decreasing our cholesterol levels)

  • Thought to have a probable role in the prevention and treatment of atherosclerosis and reducing the formation of arterial plaque and blood clots

  • Important nutrient for our adrenal function and stimulates the release of adrenal hormones like adrenaline and noradrenaline when needed

  • Helps with thyroid function

  • Works as an antioxidant preventing free radical formation

  • Indirectly protects vitamins A, E, and some Bs from oxidation 

  • Essential for maintaining our vitamin E supply

  • Improves our absorption of iron

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Depletion and Deficiency

An extreme deficiency of vitamin C is known as scurvy, which is a fairly rare disease today. The symptoms of a deficiency are generally produced by a lack of collagen formation or in other words a breakdown of tissue. This could be seen as:

  • Poor resistance to illness or infection

  • Slow wound healing

  • Easy bruising

  • General feeling of weakness

  • Loss of appetite and/or poor digestion

  • Sore or bleeding gums, mouth ulcers, loose teeth, or general poor development and health of teeth and gums

  • Nose bleeds

  • Anemia (deficiency of iron whose absorption requires vitamin C)

  • Joint tenderness or swelling

  • Bone brittleness

  • Shortness of breath

  • Reduced growth

Smokers, alcoholics, or people with inflammatory bowel disease often have lower levels of vitamin C due to the chronic needs for the vitamin.

In general vitamin C is considered non-toxic as excess amounts are eliminated from the body. However, over consumption could lead to diarrhea, nausea, a burning sensation when urinating, or skin sensitivities.  If these symptoms occur when taking vitamin C supplementation, decrease the dosage and talk to your health professional.

Dietary Sources of Vitamin C

Vitamin C is mainly found in fruits and vegetables, but can also be found in animal organ meats like the adrenal glands. The main fruit and vegetable sources are:

  • Citrus fruits (lemon, oranges, limes, grapefruit, etc.)

  • Papayas

  • Cantaloupes

  • Strawberries

  • Acerola cherries

  • Tomatoes 

  • Red & green bell peppers

  • Dark leafy greens

  • Broccoli

  • Brussel sprouts

  • Asparagus

  • Parsley

  • Cabbage

  • Sprouted whole grains, seeds, and bean

  • Rosehip 

The needs for vitamin C can vary greatly depending on the lifestyle factors of the person. However, in general our needs for this vitamin do increase during periods of stress. 

The general RDA  (a.k.a. the average daily intake recommended) for women over 19 years of age is 75mg and for men over 19 years of age is 90mg.

Still have some lingering questions about vitamin C? Just leave a comment below!

Nutrition 101 – Vitamin A

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Vitamin A, the first of the nutritional alphabet and so named as it was one of the first vitamins discovered!

There are two different forms of this vitamin: the preformed, or active form, of vitamin A is called retinol (yes, like all those anti-aging creams!). The second form is the provitamin, or precursor, forms of vitamin A called carotenoids of which beta-carotene is the most widely known and studied. Beta-carotene needs to be converted by the body into the active form of vitamin A, retinol. This is not a one-to-one process, however, in fact the rate is only around one-third.

We absorb most of our vitamin A in the small intestines as well as converting the pre-cursors to the active form. From here it goes mainly to the liver for storage (around 90%) and the rest to other organs like the kidneys, lungs, eyes, and fat tissue. 

This vitamin is in the family of the fat-soluble vitamins (along with vitamins D, E, and K), meaning its absorption into our system is aided by the presence of sufficient fatty acids and bile salts. Bile salts are what emulsify and breakdown the fatty acids in the small intestine, so without sufficient fat consumption in our diet we won’t produce enough quality bile and be able to properly absorb our fat-soluble vitamins. Another reason why fat is such an important part of balanced diet! (Read more about fat here!)

Benefits of Vitamin A

In general we tend to think about vitamin A in predominantly two areas. First there is skin health, thanks to all the retinol creams out there. Second is for eyesight – you might remember being told to eat more carrots to improve your vision? Of course there is more to this vitamin than just these two aspects! Some of the functions of vitamin A are:

  • Tissue growth and repair: overall skin health and lining of nose, eyes, intestines, lungs, and bladder, tissue repair and protection from infection or after surgery
  • Promotes eye health: health of the cornea and aiding our vision in the dark
  • Immune system: supports our white blood cell function, cancer protective, fights oxidation
  • Moisturizes our mucosal linings: lungs, nose, throat, stomach, etc. which are the immune system’s first line of defence, protecting from infection and environmental toxins

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Depletion and Deficiency

Our vitamin A levels can be depleted by various factors, such as stress and illness, alcohol use (which also depletes the liver stores), antibiotics, cholesterol or cortisone medications, laxatives, bat fats (i.e. trans-fats and vegetable oils), vitamin E deficiency, excess iron intake, and excessive exercise. 

If you have a vitamin A deficiency, you may show some of the following symptoms:

  • Eye health: eye tissue more easily irritated or inflamed, difficult seeing at night / night blindness
  • Immune system: overall decreased effectiveness, high risk of some cancers, increased vitamin C loss, increased chance of periodontal disease, kidney stone formation, ear problems
  • Skin health: acne or blemishes, dry bumpy skin (especially on the backs of the arms), rapid aging, dandruff

It should be noted that there is a possibility for vitamin A toxicity (a.k.a. too much vitamin A), but this is fairly uncommon when using dietary sources. Most of our vitamin A will be coming in the form of beta-carotene which will need to be converted.

A high intake of beta-carotene (such as excessive amounts of carrot juice) can cause a slight orange tint to the skin. But this is known to disappear once consumption is reduced.

Dietary Sources of Vitamin A

Vitamin A in its active form, retinol, is mainly found in animal sources such as grass-fed butter and other full-fat dairy products, egg yolks, organ meats (especially liver), seafood, and cod liver oil (as a supplement).

Beta-carotene on the other hand is namely found in plant-based sources in our yellow, red, and orange fruits and veggies and dark leafy greens. Some examples are:

  • Greens: asparagus, broccoli, Brussel sprouts, kale, lettuce, mustard greens, parsley, spinach, seaweed (nori)
  • Orange/yellows: carrots, pumpkin, sweet potatoes, yams, winter squash, bell peppers, apricots, cantaloupe, mango, papaya, peaches
  • Reds: red cabbage, bell peppers, cherries, watermelon

Another great reminder to eat the rainbow!


Still have some lingering questions about vitamin A? Just drop me a comment!

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