How does your body absorb and store vitamins?
Vitamins are absorbed and stored by your body in two different ways – many dissolve in water and are described as water-soluble, the others are fat-soluble so are better absorbed in the presence of a little oil or fat.
Water-soluble vitamins: These include vitamins C, B1, B2, B3, B5, B6, B12, biotin and folate. These vitamins only remain in the body for a short time before being excreted by the kidneys (apart from B12), which means you need a regular intake.
Fat-soluble vitamins: These include vitamins A, D, E and K. These are absorbed with fat through the intestine and may be stored in the liver.
Water-soluble vitamins
Vitamin B1
Also known as thiamine, vitamin B1 is needed for energy production, carbohydrate digestion, maintaining a healthy nervous system and heart function.
How can I get enough?
It’s found in wholegrain foods such as cereals, oats, rye, millet, quinoa, legumes, pork and liver. A 25g serving of yeast extract would supply your daily needs, which is 0.8-1mg. You should be able to get all the thiamine you need from a balanced, healthy diet.
Vitamin B2
Also known as riboflavin, vitamin B2 helps keep the skin, eyes and nervous system healthy and enables you to access the energy from the food you eat.
How can I get enough?
Good sources include milk, eggs, fortified breakfast cereals and rice. Vitamin B2 is destroyed by UV light, so keep these foods out of direct sunlight. You should be able to get all your vitamin B2 from your diet; an average adult needs approximately 1.1-1.3 mg a day.
Vitamin B3
Also called niacin, vitamin B3 is needed for the production of hormones, including insulin, the hormone that regulates your blood sugar levels, and also for thyroxine, serotonin and other mood and brain hormones. It’s thought to be useful for conditions including depression, arthritis and circulatory disorders.
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How can I get enough?
Vitamin B3 is found in foods that are high in protein, such as chicken, beef, fish and nuts. Breads and cereals are often fortified with niacin. A 50g serving of peanut butter with two slices of wholemeal bread will help you on your way to your daily needs. The amount of B3 you need is approximately 13-16mg a day. You should be able to obtain this from a healthy, balanced diet.
Vitamin B5
Vitamin B5, or pantothenic acid, is needed for conversion of the fats and carbohydrates in your diet to energy and also for supporting the adrenal glands, which regulate your stress response.
How can I get enough?
The best sources of B5 are fish, poultry, wholegrains (including rye, barley and millet), nuts, chicken, egg yolks, liver and green leafy vegetables. No daily amount has been set in the UK, but you should be able to get all your needs from a healthy balanced diet.
Vitamin B6
Vitamin B6 is the ‘workhorse’ of nutrients, involved in more bodily processes than any other vitamin. It functions primarily as a coenzyme, forming red blood cells, helping cells to make proteins, manufacturing neurotransmitters in the brain and releasing energy. There is also evidence to suggest that it plays a role in preventing and treating many diseases.
How can I get enough?
One serving of fortified breakfast cereal with a banana and one large salmon steak should get you well on your way to your daily needs. The main sources include poultry, lean red meat, egg yolks, chickpeas, oily fish, dairy produce, cabbage, leeks, bananas and wheat germ. The average amount needed by an adult is 1.4mg a day with amounts increasing during pregnancy and lactation.
Biotin (vitamin B7)
Also known as vitamin H, biotin is needed for healthy hair, nails, skin and for energy production.
How can I get enough?
It’s found in brewer’s yeast, liver, soy products, brown rice, nuts, egg yolks and fruit. The beneficial bacteria that live in your gut also make biotin, so the amount you need from your diet is dependent on your gut health.
Folate (folic acid)
Folate, or vitamin B9, is known for its role in helping to prevent neural defects during pregnancy but it is also plays an important role in the immune system, in energy production and in preventing anaemia. The man-made form of folate is referred to as folic acid.
How can I get enough?
Adults need 200mcg (micrograms) of folate each day. A serving (80g) of Brussels sprouts or fortified breakfast cereal (30g) each supply approximately 88mcg and 119mcg respectively. A glass of fresh orange juice (150ml) provides 49mcg and a slice of wholemeal bread (toasted) provides 12mcg. Other good sources include dark green leafy vegetables such as kale, spinach, asparagus, broccoli, sprouts, egg yolks, carrots, apricots, oranges, pumpkins and squashes, melons, wholemeal foods and rye.
If you’re pregnant or planning a pregnancy, you’re recommended to take a 400mcg supplement of folic acid daily until your 12th week of pregnancy.
Vitamin B12
Vitamin B12 is needed for growth, the digestive and nervous systems, as well as the production of energy and healthy blood cells. After the age of 50, the ability to absorb vitamin B12 from the food you eat declines.
How can I get enough?
A large glass of milk, an egg or a serving of fortified breakfast cereal will supply your daily needs. Animal products are the primary source of B12, these include red meat such as beef, liver and pork, shellfish and other fish, eggs and dairy produce. Vegetarians and vegans may consider fortified foods as well as sea vegetables. Most people should be able to achieve the 1.5mcg of vitamin B12 they need each day from a well-balanced and varied diet.
Vitamin C
Vitamin C supports the immune system, a healthy heart, healthy skin and gums, and helps to prevent diseases like heart disease and cancer.
How can I get enough?
An orange, half a red pepper or a generous serving of watercress provides your daily needs. Other good sources are berries, pomegranates, citrus fruits, potatoes, pumpkins, cabbage, broccoli, cauliflower and spinach. We need approximately 40mg of vitamin C per day.
Fat-soluble vitamins
Vitamin A
Vitamin A is a fat-soluble vitamin and is also known as retinol. It’s essential for growth and cell development, vision and immune function as well as for plump, youthful skin, healthy hair and for maintaining the integrity of the gut lining. It protects against infections and helps prevent disease.
How can I get enough?
We can get pre-formed vitamin A from meat, eggs and dairy while from fruit and vegetables we obtain beta-carotene, otherwise known as pro-vitamin A, our bodies need to convert this plant form into vitamin A. One 180g baked sweet potato would provide your daily needs. Other good sources include, animal products such as liver, oily fish, eggs, milk, cheese, butter as well as broccoli, dark green leafy vegetables, sweet red peppers, pumpkins, mangoes, cantaloupe melons and apricots.
The average male needs 0.7mg a day and a woman 0.6mg. Any vitamin A your body doesn’t use is stored for future use – this means you don’t need it every day.
Vitamin D
Known as the sunshine vitamin, vitamin D helps regulate the amount of calcium and phosphorus in the body, this is essential for healthy bones and may slow the progression of conditions such as osteoporosis. Vitamin D is also believed to support the immune system working with vitamins A and C and may help prevent certain cancers. We need vitamin D for our muscles to grow and for them to function properly.
How can I get enough?
Vitamin D is manufactured mainly by the skin when it’s exposed to sunlight. You should be able to get your recommended amounts by spending 15-30 minutes (depending on your age and ethnicity) outside in the sun each day from late March to early September. One can (155g) of sardines should also supply your daily needs. Other good sources include herrings, salmon, tuna, dairy produce, mushrooms and eggs – make sure you include these regularly in your diet.
Government guidelines suggest that children from the age of one and adults, including pregnant and breastfeeding women, need 10 micrograms of vitamin D each day.
Although, during the summer months, most people should be able to get all the vitamin D they need from the action of sunlight on the skin, the Department of Health recommends certain individuals supplement, especially during the autumn and winter months. Check whether you need to supplement by referring to the NHS guidelines.
Vitamin E
Vitamin E has protective, antioxidant properties and helps maintain healthy skin, a well-functioning immune system and heart.
How can I get enough?
Half a large avocado or a small handful of sunflower seeds would provide your daily needs. It’s found in all vegetable oils such as sunflower and pumpkin oils, tuna, salmon, broccoli, almonds, eggs, soya and wholegrains, including oats, rye and brown rice.
The amount of vitamin E you need is 4mg for males and 3mg for females – this should be attainable from a balanced and varied diet.
Vitamin K
Vitamin K refers to a group of vitamins that play a protective role in ageing. The vitamin is well-known for helping to build and maintain strong bones, blood clotting and wound healing. It also protects the collagen in the body and as such may support the health and youthful appearance of the skin.
How can I get enough?
It can be found in yogurt, egg yolks, fish oils, dairy produce and green leafy vegetables. An 80g serving of cooked kale or Brussels sprouts should supply your daily needs – serve with an olive oil dressing to improve your absorption. An average adult needs approximately 1 mcg for each kilogram of body weight. You should be able to get all the vitamin K you need by eating a varied diet.
A note on UK dietary recommendations
Dietary recommendations for any nutrient are based on the daily intake thought to be adequate to safely satisfy the needs of the majority of the population. Despite much research, values for optimum intakes are still being debated. The Reference Nutrient Intake (RNI) measure used in the UK is calculated from studies of the physiological requirements of healthy people, but because these studies are subject to wide interpretation, the RNI value for a nutrient can vary from country to country.
The term most of us are familiar with is the Recommended Daily Allowance (RDA) – this is the original term used to describe our daily needs for a nutrient. RDAs have now been replaced with Nutrient Reference Values (NRVs), however, the values for RDA and NRV are the same.
NRVs are the levels of essential nutrients considered adequate for most healthy people, and are guides only. Nutritional requirements often vary for specific groups of the population, for example during pregnancy and old age.
If you’re concerned that you might be at risk of nutrients deficiencies, speak to your GP or a registered dietician.
A note on UK dietary recommendations
Dietary recommendations for any nutrient are based on the daily intake thought to be adequate to safely satisfy the needs of the majority of the population. Despite much research, values for optimum intakes are still being debated. The Reference Nutrient Intake (RNI) measure used in the UK is calculated from studies of the physiological requirements of healthy people, but because these studies are subject to wide interpretation, the RNI value for a nutrient can vary from country to country.
The term most of us are familiar with is the Recommended Daily Allowance (RDA) – this is the original term used to describe our daily needs for a nutrient. RDAs have now been replaced with Nutrient Reference Values (NRVs), however, the values for RDA and NRV are the same.
NRVs are the levels of essential nutrients considered adequate for most healthy people, and are guides. Nutritional requirements often vary slightly for specific groups of the population, for example during pregnancy and old age.
If you’re concerned that you might be at risk of nutrients deficiencies, speak to your GP or healthcare provider.
Jo Lewin is a registered nutritionist (RNutr) with the Association for Nutrition with a specialism in public health. Since graduating from the University of Westminster in 2010, Jo has worked in a variety of public and private contexts, delivering weight management programmes, community cookery projects, and corporate wellness packages. Alongside trying to grow more of her own fruit and veg at her allotment, Jo works as a Nutritionist and Health Coach for Second Nature. She has contributed articles to a number of nutrition websites, including BBC Good Food.
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