We all know vitamins are extremely important for maintaining good health, so I’ve put together a short guide; good food sources, why you need them and some top tips on when and how to take supplements. I hope you find it interesting and useful.
Vitamins cannot be manufactured by the body (they are essential, pun intended in the title…), so must be consumed in the diet (Vitamin D is something of an exception). Vitamins are needed for many bodily functions, including metabolic actions and energy production; although they cannot directly be converted into energy- you need calories for that! Whilst wholefoods are abundant in vitamins, processed and refined foods lack them, making vitamin insufficiencies and deficiencies increasingly common in the average Western diet today. An insufficiency is when the body does not have enough to function optimally (but there may not be any symptoms of this), whilst a deficiency prevents functioning altogether, potentially leading to disease.
It is worth thinking about vitamins in two groups
– Water soluble vitamins (C and the eight different B vitamins)
– Fat soluble vitamins (A, D, E, K)
The water soluble vitamins cannot be stored in the body. This means that the body needs a steady supply. The body can however, build up stores of the fat soluble vitamins. The solubility impacts potential toxicity- you are unlikely to have excess vitamin C or B (and it is pretty much impossible to have too much from diet alone), although some can have mild side effects if excess supplements are taken. Some fat soluble vitamins on the other hand, can be toxic in too high dosages as can build up in the body. Most of the time this unlikely to be an issue from diet, but it is worth bearing in mind if you also take supplements.
You can find the latest advice on reference intakes for vitamins here at the British Nutrition Foundation for the UK (reference nutrient intakes or RNI), and here at the EFSA for Europe. You will find that confusingly, they vary somewhat (and the US recommendations are different again), but there are a number of factors such as age, gender, illnesses and genetic predisposition that all impact vitamin requirements, so there is no accurate right amount for everyone. Reference values should therefore be used as just that – a reference point, rather than a precise daily requirement.
Vitamins are best consumed via the diet, although good quality supplements can be useful, especially if you follow a specific diet which may make it difficult to consume enough of certain vitamins. When taking supplements, a couple of tips:
- Buy the best quality you can afford. Cheaper vitamins tend to have bulking agents and fillers, which its best to avoid if possible, and may contain less bioavailable forms of vitamins (this means that the body cannot use them efficiently or effectively)
- Generally vitamins are best taken with food for best absorption, but do check the label on whatever you are taking.
- BUT, do not take vitamin supplements with tea or coffee. The polyphenols in these drinks destroy certain vitamins or prevent them being absorbed.
- And one thing to remember – if you take a B vitamin complex, or multivitamin with B2 it can turn your urine very bright yellow, so don’t be alarmed!
Key functions and food sources:
Vitamin A: for eye health and immune function. The plant form (carotenes) also have an antioxidant action
Liver, egg yolk, dairy, yellow/ orange fruit/veg and dark green vegetables
The B vitamins are all important in energy production, and many for detoxification
Being water soluble, B vitamins are easily lost when food is cooked, especially in water. Try to steam rather than boil vegetables to help preserve their vitamins.
B1 (Thiamine): Potatoes, whole grains, meat and fish, nuts and seeds, soy beans
B2 (Riboflavin): Meat and fish, wholegrains, dairy and eggs, nuts and seeds
B3 (Niacin): Meat and fish, mushrooms, leafy greens, nuts, whole grains
B5 (Pantothenic Acid): Beef, poultry, wholegrains, potatoes, mushrooms, tomatoes, broccoli
B6 (Pyridoxine): purple fruit, green veg, potatoes, meat, fish
B7 (Biotin): Egg yolk, oats, soy beans, yeast, organ meats
B9 (Folate): legumes, leafy green vegetables, citrus fruit
B12 (Cobalamins): organ meats, fish, eggs, dairy (only found in foods of animal origin)
Vitamin C (Ascorbic Acid): an important antioxidant needed for a good immune system
Many fruits including citrus and berries, peppers, green leafy vegetables
Vitamin D: for strong bones
The majority of your vitamin D is synthesised by sunshine! Oily fish is the best dietary source
Vitamin E: a powerful antioxidant
Vegetable oils, nuts and seeds, green leafy vegetables, fish
Vitamin K: required for blood clotting
Green leafy vegetables, eg spinach and sprouts
Please note this is a very simplified guide. I am not a medical practitioner, and this should not be taken as medical advice. Always consult a health professional if you have any health concerns.
Osieki, H. (2014) The Nutrient Bible, 9th Edition
Haas, E. (2006) Staying Healthy with Nutrition
British Nutrition Foundation DRVs https://www.nutrition.org.uk/nutritionscience/nutrients-food-and-ingredients/nutrient-requirements.htm
European DRVs https://www.efsa.europa.eu/sites/default/files/2017_09_DRVs_summary_report.pdf
US DRVs http://nationalacademies.org/HMD/Activities/Nutrition/SummaryDRIs/DRI-Tables.aspx