This blog will cover water-soluble vitamins. These dissolve in waters and are absorbed and used by tissues immediately. Unlike fat-soluble vitamins, these are not stored in the body and are regularly required in our diet. Excess amounts are excreted via our urine, and toxic levels rarely build up.
Water-soluble vitamins include:
- Vitamin B1 (Thiamine)
- Vitamin B2 (Riboflavin)
- Vitamin B3 (Niacin)
- Vitamin B5 (Pantothenic Acid)
- Vitamin B6 (Pyridoxine)
- Vitamin B7 (Biotin)
- Vitamin B9 (Folate/Folic Acid)
- Vitamin B12 (Cobalamin)
- Vitamin C (which is discussed in a separate blog here)
Water-soluble vitamins are much more sensitive to heat during cooking, as well as some to light. To reduce vitamin loss, refrigerate fresh produce, keep milk out of direct sunlight, and instead of boiling vegetables, steam them. This blog covers their function, sources and recommended amounts.
Vitamin B1 (Thiamine)
Function
The main function of thiamine is to help cells within the body convert carbohydrates into energy. It is essential as well for a healthy functioning of the nervous system, heart and muscles.
What happens if you’re deficient?
Deficiency is easily preventable, however, it can be life-threatening if no action is taken. Deficiency may lead to muscle weakness, confusion, and weight loss. In more serious cases it can lead to BeriBeri, which can affect the heart and circulatory system (cardiovascular), or your nervous system.
- Cardiovascular BeriBeri (also known as wet BeriBeri) causes swelling of the lower legs, increase in heart rate, lung congestion, shortness of breath, and enlarged heart.
- Nervous system Beriberi (AKA dry BeriBeri) causes pain and tingling, loss of feeling in feet and hands, decrease in muscle strength and function, difficulty walking, mental confusion, difficulty speaking, and paralysis.
With chronic alcohol abuse it can lead to Wernicke-Korsakoff Syndrome, which affects the nervous system and causes:
- Lack of voluntary control of muscles
- Acute confused state
- Paralysis of the muscles in and surrounding the eye
- Impaired short-term memory
Malnutrition and other cases where thiamine deficiency occur can lead to Wernicke-Korsakoff Syndrome, but it is more common in chronic alcohol abuse. Although it can be treatable, symptoms can be long-lasting or permanent.
What are sources of thiamine?
- Whole grains
- Meat
- Fish
- Beans and peas
- Dairy
- Nuts and seeds
- Yeast (marmite and vegemite)
- Acorn squash
- Some fortified foods
How much do I need?
As it is a water-soluble vitamin it is not stored extensively, so it is important to get enough of it regularly. Women need 0.8mg a day, and 1mg a day for men (ages 19-64). You should be able to get enough from your diet, and supplementation is not necessary unless your doctor has prescribed it to you (usually they will prescribe a b-complex supplement).
There are those at risk of deficiency including: lower absorption or increased excretion of thiamine due to chronic alcohol misuse; certain medications; protein-calorie malnutrition; protracted vomiting (continuous); those who have had bariatric surgery; and certain genetic abnormalities.
Vitamin B2 (Riboflavin)
Function
Riboflavin is a bright yellow compound which enables us to utilise energy from food, as well as keeping our skin, eyes and nervous system healthy. It helps with the metabolism of iron, and protecting our cells from oxidative stress. Riboflavin is sensitive to light and can be destroyed by UV rays, so it’s best to keep foods containing it out of direct sunlight.
What happens if you’re deficient?
Deficiency is rare in developed countries, due to being in several different foods. However, it can occur in the elderly and in alcohol abuse. Symptoms include inflamed sides of the mouth; cheilosis (inflamed and cracking corners of the mouth); inflamed tongue; and cataracts.
What are sources of riboflavin?
- Eggs
- Dairy (milk)
- Nuts
- Broccoli
- Mushrooms
- Soybeans
- Green leafy vegetables
- Whole grains
- Brussel sprouts
- Some fortified products
How much do I need?
Those aged between 19-64 years need 1.3mg for men, and 1.1mg for women. Unless recommended by your doctor or health-care professional, you should not need to supplement with riboflavin as you should be able to get enough through a varied diet.
Vitamin B3 (Niacin)
Function
Enables us to utilise energy from the foods that we eat, as well as the normal functioning and keeping our nervous system and skin healthy.
What happens if you’re deficient?
Deficiency is rare in the UK and developed countries, but deficiency can lead to a condition called Pellagra. Pellagra symptoms include digestive problems; diarrhoea; dermatitis; and dementia. The skin reacts when exposed to UV light and becomes dark and scaly, and the skin may become cracked and ulcerated.
What are sources of niacin?
- Meat
- Fish
- Milk
- Eggs
- Nuts
- Green vegetables
- Beans
- Wholegrain cereals
- Some fortified foods
You can also make niacin from the amino acid (a protein) called tryptophan.
How much do I need?
For those aged 19-64, men need 16.5mg a day, and women need 13.2mg a day. As with all of these, unless recommended by your GP or a health-care professional, you should not need to supplement with B3, as you should be able to get enough from your diet. Excess high doses of niacin could cause liver problems.
Vitamin B5 (Pantothenic Acid)
Function
Pantothenic acid plays a role in fat and carbohydrate metabolism; the synthesis and metabolism of steroid hormones, vitamin D, and some neurotransmitters; and helping reduce tiredness and fatigue.
What happens if you’re deficient?
Deficiency is very rare, and usually will only be found in those with severe malnutrition.
What are sources of pantothenic acid?
- Chicken
- Beef
- Potatoes
- Oats
- Tomatoes
- Kidney
- Eggs
- Broccoli
- Pulses
- Wholegrains
How much do I need?
In the UK there is no recommended amount, as you should be able to get enough from your diet alone.
Vitamin B6 (Pyridoxine)
Function
Pyridoxine has many roles in maintaining normal functioning of the nervous system; normal protein and glucose metabolism; getting energy from food sources; the formation of red blood cells; regulating hormone activity; and normal functioning of the immune system.
What happens if you’re deficient?
It is rare, as you can find B6 in multiple sources, but if deficient it is usually seen alongside other low levels of B vitamins including B12 and Folic Acid. It can lead to dermatitis with cracks at the corners of the mouth, swollen tongue, and neurological issues including depression and confusion.
What are sources of pyridoxine?
- Poultry
- Meat
- Fish
- Pork
- Eggs
- Milk
- Wholegrains
- Oats
- Peanuts
- Soybeans
How much do I need?
1.4mg for women and 1.2mg for men, aged 19-64 years. You should be able to get enough of it through your diet alone if varied and balanced. Excess vitamin B6 (+200mg) could lead to loss of feeling in both your arms and legs.
Vitamin B7 (Biotin)
Function
Biotin plays a role in fat and carbohydrate metabolism, as well as the normal functioning of the nervous system; psychological functioning; and healthy hair, nails, and skin.
What happens if you’re deficient?
It is very rare, and in healthy individuals eating a normal diet has never been reported. However, symptoms include confusion, muscle pain, hair loss, swollen tongue, cracking on the corners of the mouth, insomnia, and depression.
What Are Sources?
- Liver
- Meat
- Fish
- Seeds
- Nuts
- Eggs
- Dairy
- Sweet potatoes
- Grains
How much do I need?
There is no recommendation, as we need biotin in such small amounts. You should be able to get enough through diet alone, and supplementation is usually not required. However, if you wish to supplement aim to take 0.9mg or less as this is unlikely to cause any harm. Bacteria in your gut can also make biotin, and some of it is absorbed through your intestinal wall.
Vitamin B9 (Folate/Folic Acid)
Function
Folate is also known as Folic Acid which is a man-made form. Folate helps to form healthy red blood cells, as well as preventing neural tube defect in foetuses (see ‘How Much Do I Need’ for more information). Its role is to form healthy red blood cells (together with B12), as well as normal cell division; normal nervous system structure; normal synthesis of amino acids; normal immune functioning; and the development of the neural tube in the embryo - this later develops into the spinal cord and skull.
What happens if you’re deficient?
Our body can store a small amount in relation to requirement needs, and a deficiency can occur in a few months. A deficiency leads to folate deficiency anaemia (megaloblastic anaemia) which leads to abnormally large immature red blood cells - this means our organs and tissue do not get enough oxygen. Symptoms include, tiredness, shortness of breath, swollen tongue, lack of energy, mouth ulcers, pins and needles, muscle weakness, forgetfulness, and depression.
What are sources of folate?
- Chicken
- Green leafy vegetables
- Wholegrains
- Liver
- Broccoli
- Brussel sprouts
- Peas
- Chickpeas
- Fortified products
How much do I need?
Adults in the UK need 0.2mg for males and females aged 19-64 years. In the UK women are recommended to supplement with 400mcg (0.4mg) of folic acid to prevent birth defects, including neural tube defect (such as spina bifida), and 40% of cases of neural tube defects are fatal. Supplementation should be taken 3 months prior to conception, and up to 12 weeks of pregnancy. It is important to note that around half of pregnancies are unplanned as well.
Extra information
In the UK, it is likely that flour will be soon fortified with folic acid, previously this wasn’t done due to the concern of masking a B12 deficiency (which as you’ll read in the next tip can cause serious damage to the nervous system if not treated). This concern is especially raised for older people, whereby vitamin B12 absorption decreases, and those who may not get enough B12 (predominantly vegans and vegetarians).
Vitamin B12 (Cobalamin)
Function
B12 (cobalamin), is a water-soluble vitamin, and is synthesised by bacteria. It contains the mineral cobalt, making B12 the largest and most complex structure for a vitamin. It is involved in maintaining a healthy nervous system. It is also needed to help red blood cells divide; normal functioning of the immune system; normal psychological function; as well as energy production from fats and proteins.
What happens if you’re deficient?
Deficiency can lead to permanent damage to the nervous system, anaemia (megaloblastic), and elevated homocysteine levels. Some of the symptoms include weakness, tiredness, numbness, tingling in arms and legs, diarrhoea, poor memory, and confusion.
What are sources of cobalamin
- Meat
- Salmon
- Milk
- Cheese
- Eggs
- Some fortified dairy-free milks, yoghurts, and cereals
How much B12 do I need?
The recommended intake in the UK for B12 is 1.5 micrograms a day for those aged 19-64.
If you eat fish, meats, and dairy you should get enough from your diet alone. Interestingly 10-15% of those over 60 years have a B12 deficiency so it is important to be aware of how much you are getting, and if concerned talk to your doctor and ask for a blood test to check your levels.
What about vegan and vegetarian diets?
If you do not consume meat, it is important that you are aware of how much B12 you are getting daily. If you do not consume enough from fortified foods, it would be wise to consider supplementing with B12. As mentioned, the UK’s recommendation is 1.5mcg per day. However, it is recommended on a vegan diet to try and eat fortified foods 2-3 times a day, or you can take a supplement: either daily 10mcg, or weekly containing 2000mcg of B12. Absorption of B12 ranges from 50% for 1mcg to 0.5% for 1000mcg. This higher level of supplementation ensures that you are getting enough.
Other blogs you might be interested in:
- Protein
- Carbohydrates
- Water-Soluble Vitamins: Vitamin C
- Fat-Soluble Vitamins
- Nutrition & Immune Health
- Foods to Feed Your Skin
- Antioxidant vs Anti-inflammatory
- Guide to Bone Health
- Following a Plant Based Diet pt 1
- Following a Plant Based Diet pt 2
Daisy, MSc PGDip ANutr, is a Registered Associate Nutritionist with a Master's Degree in Public Health Nutrition, and a Post Graduate Diploma in Eating Disorders and Clinical Nutrition, both of which are Association for Nutrition (AFN) accredited. She, also, has a BSc degree in Psychology and Cognitive Neuroscience; and has completed an AFN accredited Diet Specialist Nutrition course.
Daisy has worked for an NHS funded project, the Diabetes Prevention Programme; and shadowed a nutritionist in Harley Street.
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Any information provided by us is not intended to diagnose, treat, cure or prevent disease. We always recommend referring your health queries to a qualified medical practitioner.
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