BBC's Trust Me I'm a Doctor reveals the best mood-boosters

You really are what you eat – and your brain health and mood are no exception.

That was the overwhelming verdict of experts looking at how food affects our mental health in the latest episode of the BBC series Trust Me I'm a Doctor.

The show, which airs on Wednesday night, explores in detail the impact of food on the brain.

The findings are fascinating – and reveal just how crucial a healthy diet is to feeling happy.

For example:

Junk food really can affect our mental health by causing blood sugar highs and lows. This interferes with brain chemicals that affect mood. Protein is vital to make serotonin and dopamine – which are key to our mental health There are crucial nutrients that our brain requires in tiny amounts that can really affect our mental state. They include B vitamins, iron, calcium, magnesium, chromium, zinc and selenium.

But how exactly does each of these so-called trace nutrients affect the brain and our mood?

What are the best food sources and how much of them do you need for maximum brain function?

Below, I look at each one – B vitamins, iron, calcium, magnesium, chromium, zinc and selenium – and give the definitive answer…

Dr Sarah Brewer gives her take on how to make a diet that feeds your brain

Dr Sarah Brewer gives her take on how to make a diet that feeds your brain


When you feel tired, do you reach for a sweet snack? And when you're upset, do you find solace in chocolate, ice-cream or a bag of chips?

Research confirms that you are more likely to turn to junk food when you're in a bad mood, as their high fat and sugar content activates pleasure centres in the brain, triggering the release of 'feel-good' neurotransmitters such as dopamine and serotonin.

But there's a catch. Self-medicating with junk food also leads to blood sugar highs and lows that interfere with how these brain chemicals function to regulate mood. The overall effect can worsen your mental health.

Avoiding quick-fix, unhealthy snacks and selecting healthy foods instead can help you overcome mood swings by providing the nutrients your brain needs in tiny amounts to maintain normal mood.


BRAIN BENEFIT: B group vitamins are involved in energy production in cells, including brain cells. They reduce tiredness and fatigue, improve nervous system function, aid memory, psychological function and cognition – the ability to think straight.

Being stressed, drinking alcohol or eating sugary foods can all deplete our level of B vitamins. And a lack of B vitamins also leads to anxiety and irritability, making symptoms worse.

Researchers have found that women with low levels of vitamin B1 (thiamin), for example, are more likely to feel less composed, less confident and more depressed than those with higher levels.

When they increased their intake of foods rich in vitamin B1, they reported a marked improvement in mood and self-confidence as their thiamin levels increased.

Other studies show that correcting low levels of vitamin B2 (riboflavin), vitamin B6 (pyridoxine) and vitamin B12 has beneficial effects on well-being, self-confidence and mood.

The B vitamins in milk help reduce tiredness and fatigue, improve nervous system function, aid memory, psychological function and cognition

The B vitamins in milk help reduce tiredness and fatigue, improve nervous system function, aid memory, psychological function and cognition


1mg a day for men, 0.8mg a day for women


Yeast extracts: Whether you love it or hate it, Marmite is an excellent source of B vitamins. Each 4g serving provides between a fifth and a half of your B1, B2, folic acid and B12 needs. Although its often criticised for its salt content, a single serving provides an acceptable 0.4g salt.

Milk is an excellent source of riboflavin and provides 0.2mg vitamin B2 per 100ml, (half a small glass of milk of milk) plus 0.4mcg vitamin B12. Live yoghurt is especially good as it provides probiotic bacteria which were recently found to interact with serotonin receptors in the gut to improve mood - and may even influence food choices.

Oily fish such as salmon are often referred to as brain food due to their high level of omega-3, but they are also good sources of B vitamins, including B6 and B12 plus protein, which provides the raw materials to make brain chemicals. Try to eat fish at least twice a week, of which at least once is oily.

Turkey is a rich source of vitamin B3, with a typical turkey burger providing 4mg. The poultry also provides amino acids such as tryptophan and tyrosine which are needed to make brain chemicals such as serotonin and dopamine.


It's known as the bone boosting vitamin, but we need vitamin D for much more than that…

Not only is it needed for calcium absorption in the gut, it's also involved in regulating mood. 

Deficiency can cause headache, loss of appetite, mental fatigue, low mood and irritability. 

Lack of vitamin D is believed to play a role in depression and seasonal affective disorder. 

Average dietary intakes of vitamin D are just 3mcg per day, yet we need at least 10 mcg per day to avoid deficiency effects such as reduced immunity. 

Public Health England recommends that everyone over the age of one year takes a vitamin D supplement of 10mcg per day. 

This is very much a minimum. Older people need more and supplements providing 25mcg to 50mcg per day are ideal for those over the age of 50 years.

Look for supplements supplying vitamin D3 which is body ready and there are different delivery methods now available also such as Healthspan Super Vitamin D3 Gummies.

Brown rice: A serving of 100g (1/2 a small bowl) cooked brown, long-grain rice gives you thiamin, niacin and vitamin B6. By providing wholegrain fibre, brown rice also helps to maintain more even glucose levels.

Alternatively, supplement with a vitamin B complex, such as Healthspan Vitamin B Complex, which contains 8 essential B vitamins including B1,2,12.


BRAIN BENEFIT: Iron is needed to transport oxygen to the brain, needed by enzymes involved in neurotransmitter metabolism – and is also needed for the production and function of brain chemicals (neurotransmitters).

Lack of iron leads to anaemia, impairs your ability to think straight and leads to low mood and depression. Lack of iron is the most common deficiency worldwide and the National Diet and Nutrition Survey (NDNS) data shows that 27 per cent of women, and as many as 48 per cent of teenage girls get less iron than is needed to prevent these deficiency symptoms.


8.7mg a day for men (19-64 years)

14.8mg a day for women (19-50 years)

8.7mg a day for women (50-64 years)


TIP: A 100g (3.5oz) serving is roughly a deck of cards in palm in your hand e.g. a standard chicken breast is around 125g

Pigs' liver: a 100g serving of fried liver provides 17mg iron.

Black pudding: not surprisingly, as it's made from blood,

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