bb vitamins A-K

The A – K Vitamin Guide

posted in: Nutrition, Supplements | 0
  • Vitamin A
  • Vitamin B
  • Vitamin C
  • Vitamin D
  • Vitamin E
  • Vitamin F
  • Vitamin K

I’m sure as a child you were told many times by your folks to eat your fruit and veggies to get in your daily vitamins. You may not have always wanted to eat them, but knew they were important, and still are. What you didn’t know as a child and perhaps now is why they are important, what they are and what is the best way to get these. This A – K vitamin guide is here to answer all your questions.

Vitamins are essential micronutrients that are needed for the proper functioning of the body. These include a healthy immune system, cell repair, strong hair and nails and much more. Most vitamins cannot be produced naturally within the body. They need to be sourced from certain plant and animal products. Of the ones synthesised in the body, only very small amounts are made, hence the need for food sources and supplements. Some are water-soluble and others fat-soluble meaning they dissolve in water or fat, respectively. Water-soluble ones include your B’s and C vitamins and cannot be stored if there is an excess. Fat-soluble ones (A, D, E, K vitamins) are stored in the liver if there is too much.

Vitamin A

Along with vitamin D, E and K, vitamin A is a fat-soluble (1). It needs fat to be digested and absorbed and gets stored in the liver if too much is consumed. Vitamin A comes from plant sources in an inactive form (provitamin A) commonly known as beta-carotene, and animal sources in an active form (preformed vitamin A) (2, 3). Other names for preformed vitamin A include retinol or retinal acid. You may have heard of these names from topical products used to help with acne.


It is naturally found in the form of beta-carotene of plant foods that are yellow, red, orange and green (4). These include carrots, peppers, spinach, sweet potato, mango and papaya. Animal foods that contain vitamin A include liver and organ meats (very high in A vitamins), meat, chicken, fish, and different dairy products (cheese and yoghurt).


  • It is important for your eye health. A lack of adequate vitamin A can result in night blindness (5).
  • It helps to support a healthy immune system. Vitamin A plays a crucial role in maintaining the natural defence of the body.
  • Due to its immune support, it helps to lower the risks of specific kinds of cancer. It does so by helping in the growth and development of your cells.
  • Important in building strong and healthy bones.
  • Keeps skin and lining of the nose healthy
  • Vitamin A can help to improve the skin, specifically acne.


As extra fat-soluble vitamins, such as vitamin A is stored in the liver, consuming too much can be very harmful and toxic on your body. Too much can cause a condition called hypervitaminosis. Symptoms of this include changes in vision, bone pain, and skin challenges. It can be very harmful during pregnancy and affect your unborn child.

Signs to tell if you are deficient

There are many symptoms that may show if you are deficient in vitamin A (6). But these could be caused by other reasons too, for example, diarrhoea may be caused by a stomach bug or food you have eaten.

  • Changes in vision, especially at night
  • Dry or itchy skin or eyes, dry hair or brittle nails, broken skin
  • Loss of tears or sores in the eyes
  • Diarrhoea
  • Bladder or vaginal infections
  • Slow or poor wound healing

How much do you need?

According to the NHS guidelines, adults aged between 19 – 64 should have around 0.6mg (women) and 0.7mg (men) daily. You should be able to get this all through your diet, and supplementing this is usually not needed and can be harmful. If you don’t get enough in one day, your liver will store it until more is needed.


Pregnant women or women trying to get pregnant must not take any supplements or multivitamins contain vitamin A as this will be very harmful for your unborn child. Regular amounts through your diet are safe, but avoid trying to eat foods very high in vitamin A such as liver and other organ meats.

Vitamin B

Vitamin B (vitamin B complex) is a group of B vitamins which are water-soluble (7). This means they dissolve in water, and if you consume too much, you will pee most of this out. This group of vitamins includes thiamine (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), biotin (B7), folate or folic acid (B9) and cobalamin (B12). Although some of these are more commonly known by their “B -number” name, others are often referred to by their scientific name. We will refer to their more common names below.

Sources and Recommended Intakes

Most of the foods we eat contain our B vitamins, and it is important to have these sources every day. This is because vitamin B is water-soluble and cannot be stored.

VitaminFood SourcesDaily reference value for adults (age 19 – 64 years)
Thiamine (vitamin B1)Eggs, wholegrains, liver, fresh and dried fruit and fortified cereal0.8mg (women)
1.0mg (men)
Riboflavin (vitamin B2)Milk, eggs, rice and fortified cereal1.1mg (women)
1.3mg (men)
Niacin (vitamin B3)Meat, fish (Salmon is 50% the RDA), milk, eggs and wheat flour13.2mg (women)
16.5mg (men)
Pantothenic acid (vitamin B5)Porridge, potatoes, chicken, meat, eggs, wholegrains, broccoli, tomatoes, kidneysNo daily reference value has been established in the UK. Supplements containing 200mg or less are considered safe (8)
Vitamin B6 (pyridoxine)Milk, eggs, potatoes, fish, poultry, pork, vegetables, wholegrains, bread and peanuts 1.2mg (women)
1.4mg (men)
Biotin (vitamin B7)Very small amounts are found in a wide range of foods, but it is mostly made by the bacteria in your gutThere is no set recommendation for this in the UK, but supplements of 0.9mg or less are considered to be safe
Folate (vitamin B9)Most green vegetables included green leafy veg (spinach, kale), broccoli, peas, brussels sprouts, chickpeas, liver (high in Vitamin A, so avoid during pregnancy). Supplement form is known as folic acid200μg (micrograms) per day, except if trying to get pregnant or during pregnancy (up to 12 weeks) where 400μg is recommended
Vitamin B12 (cobalamin)Cheese, eggs, milk, fish (mainly salmon and cod), meat, some fortified cereals1.5µg (micrograms) per day. Vegans and vegetarians are likely to be low in this and may require a B12 injection


All of the vitamin B’s provide many important benefits. Some have the same benefits, while some may have their own important roles to play. Vitamin B’s are important for:

  • Keeping the nervous system and skin healthy
  • Helping to form healthy blood cells
  • Increasing energy levels and promoting brain function
  • Promoting good digestion, cardiovascular health, and a healthy appetite
  • Helping to promote the production of hormones and cholesterol
  • Preventing folate or vitamin B12 anaemia
  • Breaking down fat (biotin)
  • Preventing neural tube defects in pregnant women (folate or folic acid)


Excess vitamin B6 can lead to peripheral neuropathy (9). If you are supplementing, it is important to not take more than 200mg a day. An excess of niacin (vitamin B3) can cause skin flushes. Too much folic acid (supplement form of folate) may not be harmful, but can hide symptoms of a vitamin B12 deficiency leading to damage of the nervous system. There is not enough evidence to determine the effects of taking too much thiamine, riboflavin, pantothenic acid, biotin and vitamin B12. It will be difficult to have too much of any B vitamins through food sources, but if you take supplements, this should be taken with caution.

Signs to tell if you are deficient

It is rare to be deficient in most B vitamins, but the most common are folate and vitamin B12. This more commonly occurs in people who follow a vegan or vegetarian diet where many foods containing these vitamins are avoided or limited. Most vitamin B’s have similar clinical signs, but some produce more prominent ones:

  • Muscle weakness (mainly thiamine deficiency)
  • Cracked or sore mouth (mostly riboflavin or vitamin B6 deficiency)
  • Swollen or red tongue (mostly niacin deficiency)
  • Skin rashes (mostly vitamin B6 deficiency)
  • Fatigue (possibly vitamin B12, folate or biotin deficiency)
  • Anaemia (folate or vitamin B12 deficiency)
  • Tingling of hands or feet (possible peripheral neuropathy, possibly Pantothenic acid deficiency)
  • Dry or brittle skin and hair (mostly biotin deficiency)

Vitamin C

Ascorbic acid or vitamin C is another essential micronutrient with many important roles in our body’s health (10). It functions as an antioxidant in the body and is a coenzyme for the various biochemical pathway. It is probably the most unstable of all the vitamins and can be easily destroyed and diminished.

Like with the B vitamins, it is water-soluble and our bodies can’t store it. Because of this, we need to have it every day. If we have too much of it, the body will usually expel this through your urine. But sometimes the body can’t get rid of it fast enough and it can have some negative side effects.

Sources and Recommendations

Vitamin C is the only vitamin that cannot be found in animal products. Its main sources are from fruit and vegetables. But many people choose to take a supplement to get in extra vitamin C. This is often not necessary as you should be able to get this if you are eating at least 5 portions of fruit and veg daily (11). And taking extra from a supplement is most likely going to be peed out anyway.

The UK guidelines recommend adults aim for 40mg daily. This is fairly low compared to the US of 90mg per day.

Some fruit and vegetables are much better sources than others. Foods highest in vitamin C include:

Fruit or VegetableVitamin C per 100g
(% RDA – UK)
Guavas228mg (570%)
Peppers128mg (320%)
Kiwis93mg (232%)
Broccoli89mg (222%)
Papaya61mg (152%)
Snow Peas60mg (150%)
Strawberries59mg (148%)
Oranges53mg (133%)
Tomatoes23mg (58%)
Kale18mg (45%)
My Food Data


  • Promotes a healthy immune system by supporting white blood cell production – important for protecting the body against infection
  • As it is an antioxidant, it helps protect cells (such as white blood cells) from free radicals and other harmful molecules
  • Involved in the production of collagen, helps repair tissue and reduced damage from inflammation. It is therefore helpful in wound healing
  • It helps in forming and maintaining healthy bones, cartilage, blood and skin
  • Can help improve iron absorption
  • May help in protecting your memory and thinking as you get older
  • May reduce the risk of chronic disease (ie. heart disease), help in managing blood pressure

Other claimed benefits such as preventing cancer and preventing a common cold, unfortunately, have not been proven. However, as vitamin C does help in the immunes defence and supports white blood cells, it may have indirect effects. One study done in 2013 did find evidence to support that using high doses of intravenous vitamin C may benefit cancer patients (12). A further study from 2015 shows to support this finding.


Although excess vitamin C is unlikely to cause any issues, taking very high doses of a vitamin C supplement (over 1000mg daily) may cause some disturbances. As it will not all be absorbed by the gut, an excess could cause diarrhoea or kidney stones.

Signs to tell if you are deficient

A vitamin C deficiency used to be common back in historical times. It was especially common in men who worked on ships, who spent a long time out at sea. Fruit and vegetables would quickly spoil, and vitamin C content would quickly deplete. As a result, they got scurvy, a disease caused by a lack of vitamin C.

Although scurvy is no longer common, it can still occur in poor elderly patients, those with a history of mental or chronic illness or alcoholism (13). Vitamin C deficiency symptoms may present as:

  • Fatigue
  • Slow wound healing
  • Inflammation and sometimes bleeding gums
  • Dry and damaged skin, also may show as bumpy or rough
  • Bruising easily
  • Corkscrew hair
  • Occasionally depression
  • Possible iron deficiency (as vitamin C plays a role in iron absorption)

Vitamin D

You may know it as the sunshine vitamin, or more formally as calciferol, but believe it or not, Vitamin D is a hormone (14). The reason for its sunny nickname is that vitamin D is created by the body when direct sunlight hits the skin. Unfortunately, between October to March (in the northern hemisphere), we are not able to make enough vitamin D from the sun. Although there are small amounts in food, this is the one vitamin recommended to take as a supplement over food. Also, with the use of sunscreen protecting the skin from sunburn, this can limit our vitamin D production. The same applies to sunlight going through glass, which is indirect and does not have the same effect.


As already mentioned, the main source is through direct sunlight. But as we don’t get enough of this all year round, and need to protect our skin from burning during summer, a supplement is the way to go. Vitamin D comes in two main forms – vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol) (15). Vitamin D2 is usually found in plant food sources, and vitamin D3 from animal food products. Most supplements are in the form of vitamin D3.

Although foods don’t tend to contain enough vitamin D and it will be hard to reach the recommended daily dose, it is still helpful to include these foods as part of a healthy diet. These include oily fish such as salmon and sardines, liver, egg yolks, mushrooms, yeasts and some fortified foods.


  • Involved in regulating phosphate and calcium in the body. Therefore it is essential for bone health, muscles and teeth
  • May help to prevent depression and low mood
  • Vitamin D may promote a healthy immune system
  • May help reduce risk of cancer, diabetes, heart disease and other chronic diseases
  • Vitamin D may aid weight loss

The many possible effects of vitamin D are continuously being looked into with countless studies researching its effects. Although we can’t confidently say it can help reduce the risk of cancer or aid weight loss, previous study results do look promising.


Excess intake of Vitamin D causes issues like elevated blood levels, nausea, vomiting, poor appetite, stomach pain, constipation, diarrhoea, and kidney failure in extreme conditions.

Signs to tell if you are deficient

A vitamin D insufficiency and deficiency is very common in the UK, but around the world too – even in hot countries. The main health issues of vitamin D deficiency is rickets (a bone malformation) in children and osteomalacia (softening of the bones) in adults. Other signs may include:

  • Fatigue and extreme tiredness
  • Low mood and depression
  • Often getting sick, such as having a common cold or getting infected
  • Bone and joint pain, including bone loss and lower bone density
  • Muscle pain (a large percentage of people with fibromyalgia have low levels of vitamin D)
  • Possible hair loss

How much do you need?

According to the NHS guidelines, children from the age of 1 years old and adults (including pregnant women) should have 400 IU (international units) daily (16). This is equivalent to 10μg (micrograms). Babies under the age of one should have 8.5 – 10μg daily. This level is considered safe and is helpful in maintaining a healthy vitamin D level.

However, if your levels are very low, you may require higher amounts short term to help boost this. It is advised to have this level tested first and speak to a doctor or dietitian to be given a recommended dose to take. In is important to note that other countries, the daily dose recommended is much higher, but this is not recommended in the UK without supervision.

People at higher risk of being deficient include overweight and obese people, people with darker skin tones, elderly, people who stay indoors or wear sunscreen always and people who live in darker, cooler climates, far from the equator.

Vitamin E

Another fat-soluble vitamin and antioxidant on. the list is Vitamin E, also known as tocopherol (17). Like all vitamins, it is essential for the body, but is often found in topical creams such as moisturisers to help with dry skin. It mainly benefits us by protecting our cells from free radicals, targeting the skin and also involved in cardiovascular health.


Vitamin E is found in a large array of foods, so you are unlikely to become deficient in this. Plant-based foods include wheatgerm, sunflower oil and seeds, and almost all seeds, nuts, nut butters and oils. It is also found in avocado, kiwis, mangos, broccoli and green leafy vegetables. Animal sources include salmon, rainbow trout, lobster and crayfish, snails, goose meat and abalone (the richest animal source).


  • It helps maintain healthy skin and also eye health
  • Plays a role in the nervous system
  • Helpful in supporting the immune system
  • Can help reduce signs of ageing on the face.
  • May play a helpful role in cardiovascular health, inflammation and cancer – but the evidence is lacking for these benefits


Higher levels of vitamin E from food is unlikely and there is insufficient evidence of the harms of having too much. However, some studies suggest taking too much of a vitamin E supplement can cause side effects, of which the most pressing being a stroke (18).

Signs to tell if you are deficient

A vitamin E deficiency is unlikely to occur in healthy individuals. But may occur in people with chronic illnesses where fat is not properly absorbed or digested, such as Crohn’s disease. As vitamin E is fat-soluble, it means it needs some fat in the gut to help absorb it. Signs of a deficiency may include:

  • Nerve and muscle damage
  • Weakness of muscles
  • Loss of body movement control
  • Vision problems

How much do you need?

The NHS suggest a recommended amount of 3mg for women and 4mg for men daily (19). This should easily be met through the foods that you eat.

Vitamin F

This is not a vitamin in the traditional sense compared to the other vitamins, but rather the original or old fashioned name from the 1920’s given to two types of essential polyunsaturated fatty acids (20). They are more commonly known as ALA (alpha-linolenic acid) and LA (linoleic acid), and are mostly plant-based forms of omega 3 and omega 6 respectively. The body is capable of producing all fatty acids, except ALA and LA. Thus food sources of these are important. ALA gets changed into EPA and DHA (the type of omega 3 found in oily fish) in the body, but the process is slow and not much is utilized. Thus larger amounts of plant-based omega 3 is needed to have an impact compared to animal sources of omega 3.


Natural sources of ALA include rapeseed oil, walnuts, walnut oil, flaxseed oil and flaxseed or linseed, chia seeds and algae. Foods rich in LA include eggs, avocado oil, almonds, cashews, peanut butter, hemp, tofu, safflower oil and walnuts. Some of these foods may contain both types of fatty acids. Except for eggs, all other omega 6 is found in plant-based sources. But omega 3 doesn’t only come in the form of ALA (which is plant-based), but also EPA and DHA mostly found in foods such as oily fish such as salmon, mackerel and sardines.


ALA and LA (or vitamin F) are fatty acids that fit into the omega 3 and omega 6 group. In the western world, it is common for people to have a much higher ratio of omega 6 (included LA) than omega 3. Most people tend to have a ratio of around 17:1 omega 6 to omega 3, but sometimes much higher. A good aim would be to reach a ratio of 3:1, but in an ideal world, this would be a 1:1 ratio. Both play a vital role in the body’s health, but too much of one on a constant basis will throw out your ratio. These benefits include:


  • As an omega 3, it has anti-inflammatory properties and may be beneficial for people with joint pain and arthritis
  • It may play a role in heart health and brain health, including depression, but there is insufficient evidence to support this
  • ALA plays a role in pregnancy and breastfeeding, supporting the health of the baby


  • As an omega 6, it has more inflammatory properties which is important when the body is under stress or has suffered any injury.


The main concern of having too much of is more about affecting the ratio of omega 6 to omega 3. Too much of one can counteract the effects of the other.

Signs to tell if you are deficient

An omega 3 deficiency can be common as most people in the western world do not eat enough of these. Possible signs of a deficiency include brittle or soft nails, dry skin and hair, a lack of concentration, mood swings and fatigue and possible poor wound healing. An omega 6 deficiency is unlikely, and having too much is more of a concern.

How much do you need?

If you don’t eat oily fish and rely on plant-based food for your intake of omega 3 (in the form of ALA), try to have small amounts of these foods daily. One tablespoon of chia seeds daily is roughly equivalent to 2 – 3 portions of oily fish in terms of omega 3 intake, which is the recommended amount per week. You should already be getting in enough omega 6 from the foods you eat, but try not to overdo these foods if you want to improve your omega 3 intake and ratio.

Vitamin K

The last vitamin and last fat-soluble type on the list is vitamin K. It has some important functions and as it is a fat-soluble vitamin, if your body doesn’t need that you take in, it will store it for when it does.


Sources of vitamin K include green leafy vegetables such as spinach, collards, kale, Swiss chard, some types of lettuce, broccoli and vegetable oil. Smaller amounts are also found in and cereal grains, eggs, meat, fish, liver and dairy products.


  • Its main role is blood clotting and involved in wound healing
  • Some research suggests it may play a role in bone health


Not enough research has been done about the effects of having too much vitamin K. However, for people taking warfarin or other blood-thinning medication, it is usually advised by their doctor or dietitian to limit the intake of vitamin K. This is because vitamin K helps with clotting and works against the purpose of the medication.

Signs to tell if you are deficient

Signs of a vitamin K deficiency include (21):

  • Excess bleeding from a wound or cut
  • Easy bruising
  • Bleeding in the gut
  • A heavy periods in women
  • Blood in the stools or urine

How much do you need?

The UK guidelines recommend adults have a daily amount of 1μg (microgram) of vitamin K per kilogram body weight. This means, for someone weighing 60kg (132 lbs or 9.5 stone), they need 60μg of vitamin K a day. This should be easily met through a healthy balanced diet. If you do take a supplement, don’t exceed 1mg total vitamin K, as although there is a lack of evidence, this may cause harm.

The Final Word

Different types of vitamins are classified as either water or fat-soluble. Water-soluble vitamins are those that dissolve in water and are not stored in the body. While the fat-soluble ones dissolve in fat and are stored if too much is consumed. All vitamins are essential to your health. You should be able to get enough of all of these by eating a healthy, balanced diet rich in fruit and vegetables, grains, protein and healthy fats, with the exception of vitamin D which should be supplemented all year round.