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Multivitamin Supplements- What You Need to Know About Them

Multivitamin Supplements- What You Need to Know About Them

In a world where the likes of whey protein, prep workout powder, amino acids etc are the primary products to fall under the “supplement” label, while yes these supplements are important in order to assist one in their endeavor for progress, there are some supplements much more essential for one’s health that are overlooked by most. The primary supplement I am referring to in this instance is the multivitamin, not the £2 Tesco branded multivitamin, I am referring to a clinically dosed supplement specific to one’s needs. In this blog I am going to elaborate on what makes a good multivitamin, key components and their dosages, along with some personal recommendations.


What is a multivitamin?

A multivitamin can be described as a product containing (you guessed it) a multitude of various minerals and vitamins, they may also include other products such as probiotics. Typically containing a vast amount of the essential vitamins and minerals required for good general health and function, these supplements can come in capsule form, powder, chewy gummies etc and are varied to accommodate those from all walks of life, elderly, young, infants, men, women etc.

The vitamin complex of most multivitamin supplements is usually comprised of vitamins A,E,D,K,C and an assortment from the vitamin B complex. Certain vitamins when paired with specific minerals can actually increase the absorption of the mineral, an example of this would be the pairing of vitamin C with Iron, as studies have shown that consuming as much as 100mg of vitamin C with a meal increased non-heme iron absorption by as much as 67%.


So why do we need these vitamins?

The necessity of sufficient vitamin intake is important for every demographic for varying reasons subjective to age, gender, existing medical conditions/ health requirements. Understanding the general function and sources of each vitamin and mineral is important in assessing individual requirements.


Vitamin A

Comprised of a group of fat-soluble compounds (retinol, retinal and retinyl esters), this vitamin is stored in the liver in the form of retinyl esters, this fat-soluble vitamin is essential for immune function, eyesight, cell growth and fetal development. Vitamin A has effective antioxidant properties as well as being a powerful immune system support, it is also essential in the forming of placenta, therefore is a must have for pregnant women. It also plays a role in sperm/ egg production in male and females, making it worth considering for those trying to conceive.

A deficiency of this vitamin can be linked to issues with macular degeneration (eyesight deterioration), anemia in pregnant women, other symptoms of deficiency also include skin conditions such as acne. An excessive intake of this vitamin can also have detrimental affects to health and is referred to as hypervitaminosis A. This excessive intake can lead to conditions such as nausea, cranial pressure, liver damage and compromised vision along with issues such as birth defects in infants. The recommended daily allowance (RDA) for vitamin A is 900mcg for men and 700mcg for women, anything consistently over 3,000mcg/d is considered the tolerable upper limit in order to prevent toxicity.


The RDA for this vitamin can be easily met through a varied diet that includes foods such as:

  • Eggs
  • Chicken liver
  • Salmon
  • Mackerel
  • Trout
  • Sweet potato
  • Carrots
  • Kale
  • Collard greens
  • Parsley
  • cabbage


Vitamin E

This fat-soluble vitamin has strong antioxidant properties and studies suggest it may even reduce free radical damage, thus mitigating the ageing process. There are few scientifically proven cases where vitamin E supplementation is required, other than to treat vitamin E deficiency.

In regards to excessive intake/ deficiencies, the RDA for vitamin E is subjective to the source of which your vitamin E is coming from, synthetic or natural (this will be displayed on the product label) for synthetic the RDA is 33.1IUs/d, while natural is 22.4IUs/d. while deficiencies are rare unless you have underlying health conditions, some symptoms include:

  • difficulty with walking/ coordination
  • muscle pain or weakness

The upper limit for consumption is 1000IUs/d, making it exceptionally hard for consumption to become toxic.

Some sources of vitamin E include:

  • nuts and seeds
  • wholegrains
  • vegetable oils
  • fortified cereals
  • leafy veg



Vitamin D

Another fat-soluble vitamin stored by the body, of which there are 2 derivatives, vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). D3 being the most effective at increasing blood levels of vitamin D and is mostly derived from animal sources, while D2 is derived from certain plants and mushrooms. Vitamin D is converted into calcidiol which is the storage form of the vitamin, then is converted to calcitriol which is the active steroid form, this then binds to the cells vitamin D receptors and allows for gene expression to occur.

Sufficient vitamin D intake/ supplementation can is important as the vitamin helps to regulate the absorption of calcium and phosphate in the body, thus improving bone and teeth strength along with supporting muscle growth. Without sufficient vitamin D, individuals run the risk of developing certain health complications such as osteoporosis and osteomalacia, along with bone deformities in infants. If consumed in excess, hypercalcemia may occur which is a build up of calcium in the body due to excessive gene expression, this can lead to bone pain and kidney problems such as kidney stones.

The RDA for vitamin D is as follows:

  • 10mcg (400IUs) for infants 0-12 months
  • 15mcg (600IUs) young adults up to 70 years
  • 20mcg (800IUs) adults over 70 and breastfeeding women

The safe upper limit for vitamin D is 100mcg/ 4000IUs/d


Vitamin K

Vitamin K is derived of a number of fat-soluble vitamins that play a role in blood clotting, bone metabolism and calcium regulation. Vitamin K is necessary in order for the body to produce prothrombin, which is a clotting factor essential for blood clotting and bone metabolism. Vitamin K comes in two forms, vitamin K1 (phylloquinone),which is a plant derivative and vitamin K2 (menaquinone), which is a derivative of animal products and some fermented foods. Research suggests there may also be a link between vitamin K, bone, cognitive and heart health.

Vitamin K1 sources are as follows:

  • Green leafy vegetables
  • Some vegetable oils

Vitamin K2 sources include:

  • Eggs
  • Spinach
  • Soybean oil
  • Parsley


Toxicity from vitamin K is exceptionally rare, therefore no upper limit has been identified, although vitamin K is known to have interactions with certain clinical anticoagulants such as warfarin as these delay/ reducing vitamin K’s clotting ability, increasing vitamin K supplementation can interfere with these processes, thus it would be advisable to keep vitamin K consumption consistent to mitigate this. The RDA for vitamin K is typically around 70-90mcgs for the average adult.


Vitamin C

Probably the most commonly recognized of all the vitamins, this vitamin (also known as ascorbic acid) is referred to as “essential” meaning your body cannot produce it intrinsically. A water-soluble vitamin found abundantly in citrus fruits, broccoli, kale, spinach and bell peppers. There are many potential benefits of supplementing vitamin C as it is an effective antioxidant, meaning it will protect the cells from free radicals that cause oxidative stress, this also gives it anti-inflammatory properties. Vitamin C is also known to be an excellent immune system support agent, as it stimulates neutrophil migration to infection sites along with facilitating heightened phagocytosis and oxidant production.

Vitamin C also plays a large role in the absorption of iron in the body, especially non-heme iron, which is the least efficiently absorbed source of iron, commonly found in plants.

The RDA for vitamin C lies at around 65-90mcgs per day with the upper limit lying at around 2,000mcgs/d, since vitamin C is water soluble it is very unlikely that high doses will become toxic as this will be excreted in urine etc, although extremely high doses may cause stomach/ bowel irritation. On the other hand, vitamin C deficiency can lead to scurvy, anemia etc with symptoms such as:

  • Slowly healing wounds
  • Damaged, dry skin
  • Rough bumpy skin


Vitamin B complex

Comprised of 8 total B vitamins including:

  • B1-Thiamine
  • B2- Riboflavin
  • B3- Niacin
  • B5- Pantothenic Acid
  • B6- Pyridoxine
  • B7- Biotin
  • B9- Folic acid
  • B12- Cobalamin

The vitamin B complex is an exceptionally beneficial group of vitamins that provide a multitude of health benefits ranging from cell health, improved digestion, improved cognitive function, better eyesight etc.

B vitamins are especially important for pregnant and breastfeeding women as they reduce the risk of birth defects, along with playing a role in fetal brain development. They are also important to consider for expectant mothers as they may improve energy levels and reduce the risk of preeclampsia.


For women the RDA for the Vitamin B complex is as follows:

  • B1- 1.1mg
  • B2- 1.1mg
  • B3- 14mg
  • B5- 5mg
  • B6- 1.3mg
  • B7- 30mcg
  • B9- 400mcg
  • B12- 2.4mcg


For men the RDA’s are as follows:

  • B1- 1.2mg
  • B2- 1.3mg
  • B3- 16mg
  • B5- 5mg
  • B6- 1.3mg
  • B7- 30mcg
  • B9- 400mcg
  • B12- 2.4mcg


These amounts are specific to the average adult, certain other demographics require specific amounts such as the older generation, pregnant women and those with certain health issues such as:

  • Coeliac disease
  • HIV
  • Crohn’s disease
  • IBS
  • Rheumatoid arthritis
  • Ulcerative colitis


Deficiencies of Vitamin B can display symptoms that include:

  • Fatigue
  • Skin rashes
  • Cracks around the mouth
  • Abdominal distress
  • Anemia


There is no toxic dose stated for humans for the vitamin B complex as it is also a water soluble vitamin meaning any excess is excreted in the form of urine, however doses consistently exceeding RDA’s may cause abdominal distress depending on previous or underlying health conditions.



In conclusion I feel that a multivitamin supplement is an excellent addition to anybody’s daily routine, with far more positive attributes than negative. Most products available on the market today will cost you little over £20 for a month supply, all containing multivitamin clinical dosages.


By Tireoghain O’Neill



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