Vitamins and minerals
Meet the vitamins and minerals people most often run short of, where to find them in food, and when a supplement makes sense.
TWO FAMILIES
13 vitamins, stored in two different ways
Your body needs 13 vitamins. They split by what they dissolve in:
- Water-soluble: the B group and vitamin C. The body doesn't store much, and extra mostly leaves in urine, so you need them regularly.
- Fat-soluble: A, D, E and K. The body stores them in the liver and fat, so you don't need them every day, but megadoses can build up to harmful levels.
A glass of orange juice today doesn't cover vitamin C for next week. A very high-dose vitamin A pill every day for months could do real harm.
Check yourself
Which group of vitamins can build up in the body to harmful levels if you take very high doses?
- Water-soluble: the B group and C
- Fat-soluble: A, D, E and K
- Neither: extra vitamins always leave the body
- Only vitamin C
Show the answer
Fat-soluble: A, D, E and K
Right. Fat-soluble vitamins are stored in the liver and fat, so megadoses can accumulate.
THE MOST COMMON GAP
Iron
Iron carries oxygen in your blood. Iron deficiency is the most common nutritional deficiency in the world and a main cause of anaemia, especially in women of reproductive age and in children. There are two kinds in food:
- Haem iron, from red meat, poultry and fish, is absorbed easily.
- Non-haem iron, from lentils, beans, dark leafy greens and fortified bread, is absorbed less easily, but what you eat with it makes a big difference.
Vitamin C in the same meal, from lemon juice, tomato, peppers or citrus, helps you absorb non-haem iron. Tea and coffee with the meal reduce it.
Same lentil stew, two ways
Lentils with a glass of tea
The tannins in tea bind to the iron in the lentils, and less of it is absorbed. A habit of tea with every meal adds up over time, especially if your iron is already low.
Lentils with lemon, tea later
A squeeze of lemon juice or a tomato salad on the side brings vitamin C, which helps absorption. Enjoy the tea an hour or so after the meal instead.
Check yourself
Nazanin eats lentils most days and her iron is on the low side. What could she add to the same meal to help her absorb more of it?
- A cup of strong tea
- A squeeze of lemon juice
- A glass of milk
- Extra salt
Show the answer
A squeeze of lemon juice
Yes. Lemon juice brings vitamin C, which helps the body absorb the non-haem iron in lentils. Tea is best moved to an hour or so later.
BONES AND TEETH
Calcium and vitamin D work as a pair
Calcium builds bones and teeth. Good sources: milk, yoghurt, cheese, fortified plant milks, tofu, sesame (and tahini), and leafy greens.
Vitamin D helps your body absorb and use that calcium. Unusually, your skin makes it from sunlight. Few foods contain much: oily fish, eggs and fortified foods are the main ones.
A bowl of yoghurt with lunch and some tahini on bread add real calcium. Vitamin D is harder to get from food alone.
Check yourself
Match each nutrient to where most people get it.
Show the answer
- Iodine → Iodised salt
- Vitamin D → Sunlight on the skin
- Vitamin B12 → Animal foods or fortified foods
- Calcium → Milk, yoghurt, cheese, sesame
- Vitamin C → Fruit and vegetables
Three more, and a rule of thumb
- Iodine keeps the thyroid working. In many countries iodised salt is the main source; Iran has used it nationally for decades. If you use salt, use iodised, but don't use more of it.
- Vitamin B12 is found almost only in animal foods (meat, fish, eggs, dairy). Vegans need fortified foods or a supplement.
- Folic acid: WHO advises 400 µg a day for women trying to conceive and in early pregnancy, to lower the risk of neural tube defects in the baby. Follow a doctor's advice on this.
- Food first. A varied diet with fruit, vegetables, whole grains, legumes and some dairy or protein foods covers most needs for most healthy people.
Check yourself
Who most needs a source of vitamin B12 such as fortified foods or a supplement?
- People who eat fish twice a week
- Vegans, who eat no animal foods
- Anyone who drinks tea with meals
- People who use iodised salt
Show the answer
Vegans, who eat no animal foods
Right. B12 is found almost only in animal foods, so people who eat none need fortified foods or a supplement.
Check yourself
Taking high-dose vitamin pills "just in case" is harmless, because the body simply gets rid of what it doesn't need.
Show the answer
False
False. Fat-soluble vitamins like A and D are stored and can build up to harmful levels, and some minerals are harmful in excess too. Supplements help specific groups with specific needs; for everyone else, more is not better.
Lesson recap
- There are 13 vitamins. Water-soluble ones (B group, C) are needed regularly; fat-soluble ones (A, D, E, K) are stored, so megadoses can harm.
- Iron deficiency is the world's most common nutritional deficiency. Vitamin C in the meal helps absorb plant iron; tea with the meal reduces it.
- Calcium comes from dairy, sesame, tofu and greens; vitamin D mostly from sunlight on skin, and low levels are common even in sunny places.
- Iodine from iodised salt, B12 from animal or fortified foods, and 400 µg folic acid for women planning a pregnancy.
- Food first: supplements help specific needs, on advice, and more is not better.