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Can the food you eat really ‘boost’ your immune system?

Can the food you eat really ‘boost’ your immune system?

Can you really ‘boost’ your immune system?

As much as I love basking in the sun, I actually love the Winter.  Cosy nights in, wrapping up in Winter woollies and the celebrations of Halloween, bonfire night, Christmas and New Year are all something to enjoy.  What I don’t relish is the prospect of Winter bugs and no matter how healthy you are, they always manage to creep their way in.

As the colder months approach, it becomes more important to eat and live well to support a healthy immune system, which helps to protect us against infections.  Even the best of us are up against it during the Winter and the challenges these months present can hamper good diet and lifestyle practices.  Comfort eating, and the influence of dark mornings and early evenings offer the perfect excuse to lapse on our healthy diet and exercise regimes.

The immunity ‘boost’ conundrum 

As Winter approaches, so comes the advice on how we can ‘boost’ our immune system to ward off infectious bugs.  The idea that you can ‘boost’ your immune system is a little misleading.  This concept conjures up a false expectation of ‘supercharging’ your immune system and in some way making it invincible to anything that attempts to challenge it. The reality is that immunity involves a system and not a single entity. There are many cells of the immune system that have to respond to many different types of microbes. Pinpointing the specific cells and defining to what degree they should be increased is hugely complex and a question that’s yet unanswered by science.

Given the intricacies of the immune response, the science behind the impact of diet and lifestyle on immunity is not definitive, but research is continuing to evolve and it’s clear that maintaining a healthy lifestyle is a key part of keeping your immune system strong and healthy.

Why do we need our immune system?

You couldn’t survive without an efficient immune system, which is made up of special cells, proteins, tissues and organs that defend the body against infectious organisms and other foreign invaders through a series of processes referred to as the immune response.

Foreign invaders in the body are referred to as antigens. These are toxins or other foreign substances that induce an immune response in the body, especially the production of antibodies. One example of an antigen is the common cold virus. What makes the immune system truly remarkable is that once it has encountered an antigen, antibodies are hard coded to fight this invader should it try to attack the body again.

Can the quality of your diet help to maintain a healthy immune system?

The simple answer is yes. Exactly how diet is linked to immunity is not fully understood but is an area of research that continues to evolve.  Scientists acknowledge that malnourished people are more vulnerable to infectious diseases, which helps to illustrate the importance of diet on immunity.

Maintaining a healthy balanced diet is key and there are many micronutrients (vitamins and minerals) required to maintain the normal functioning of the immune system.  If your diet is compromised in any way through dieting or illness for example, then you may not be eating enough food or the right quality of food that allows you to glean the nutrients required to support your immune system.

Findings from the National Diet and Nutrition Survey (NDNS) have shown that amongst certain groups of the population, intakes of certain vitamins and minerals that support immunity are lacking in the diet (1).  Vitamin D plays a key role in immunity and during the Winter months a significant percentage of people have been shown to have low levels of this nutrient, given the lack of sunshine, which is the main supplier.  Minerals such as selenium, iron and zinc also play an important role in immunity and have been shown to be lacking the diet of some people as have intakes of vitamin A.  This doesn’t necessarily mean your immune system will be compromised but that attention should be paid to eating the right foods to support healthy immunity.

Foods that can support your immune system

Diet is defined by food and not nutrients.  Eating a balanced diet consisting of whole foods such as vegetables, wholegrains, lean proteins and healthy fats, will support your immune system. However, for the purposes of this blog I’m going to lay out some of the foods that contain specific nutrients that support good immunity.

Vitamin A

Orange and green fruits and vegetables contain a pigment called beta-carotene, which is converted to vitamin A in the body. Vitamin A plays an important role in maintaining a healthy immune system (2).  This nutrient helps to maintain the integrity of the mucosal cells of the gastrointestinal tract, eye and respiratory system that function as a first line of defence to infection, forming a barrier between from the environment outside the body.  Vitamin A is also important for the normal function of immune cells and the production of antibodies that respond to infections.

Iron, selenium and zinc

All of these minerals are required for the production of antibodies, which are cells of the immune system that fight infection (3, 4, 5). Findings from the NDNS survey have shown that 27% of adult women and 54% of teenage girls do not get enough iron from their diet and partnered with menstrual blood loss, this puts them at particular risk of deficiency.  Selenium intakes are also low with 38% of adults being shown to have inadequate intakes. Zinc is also lacking the diet, with 8% of adults and 17% of teenagers shown to have inadequate intakes of this mineral (1).

You can maintain good intakes of iron by eating foods such as meat, poultry, oily fish and eggs.  Plant foods such as beans, pulses, dark green vegetables and dried spices are also a good source and you can increase the uptake of iron from these foods by partnering with foods rich in vitamin C.   Selenium is found in Brazil nuts, oily fish and wholegrain foods such as brown pasta, rice and bread. Levels of selenium do vary depending on where the food has been grown and the quality of the soil. Zinc is found in meat, shellfish, eggs, beans, pulses, wholegrains, nuts, seeds and cheese.

Vitamin C

This vitamin is the one people most associate with immunity and the common cold, which is backed up by some research suggesting its effectiveness at reducing the risk and length of infection (6).  Research has shown how several cells of the immune system accumulate vitamin C and requires this vitamin to perform their task, especially T cells and phagocytes.

Most people get more than enough vitamin C in their diet, but appetite can lesson if you do get ill, which may impact on your intake. You can keep your levels topped up by eating foods such as red peppers, citrus fruits, berries, broccoli and potatoes. Vitamin C is water soluble and easily destroyed so try not to overcook vegetables and avoid soaking before cooking.

Vitamin D

Vitamin D has been shown to play an important role in the immune system by increasing the antimicrobial effect of white blood cells that fight infection (7). Low levels of vitamin D can suppress the immune system, putting you at a greater risk of viral infections. Research involving more than 19,000 people found that those with the lowest levels of vitamin D were 36% more likely to develop a common cold than those with higher levels (8).

Findings from the NDNS have shown that 30-40% of all age groups are classed as being deficient in vitamin D due to the lack of sunshine (1). Public Health England recommends everyone takes a supplement providing 10mcg of vitamin D during the Autumn and Winter.

Gut bacteria also play a role

Over 70% of immune cells are located in the gut so it makes that a relationship exists between the two. We’re beginning to understand that it’s quality and not quantity that’s key to gut health and the diversity of microbes in your gut is referred to as your microbiome.

Probiotics are bacteria that have been shown to have a positive health benefit.  Well researched strains include those from the Lactobacillus and Bifidobacterium family.  Live yoghurt is the most well-known probiotic food and contains strains such as Lactobacillus Acidophilus and Lactobacillus Casei. Fermented foods such as kimchi, kefir and miso also contain strains of bacteria that can support good gut health.

Probiotic supplements offer a way of delivering large doses of specific bacteria to the gut and may be beneficial in the prevention of upper respiratory tract infections (URTI) such as the common cold (9). The effect of probiotics on the immune system has been widely researched and certain strains have been shown to promote the production of antibodies. The same strains have also been shown to stimulate the activity of immune cells such as natural killer cells and T-lymphocytes, which help regulate immune responses.   A Cochrane Review showed that probiotics were better than a placebo in reducing the incidence and duration of a URTI (10).

Choose a supplement that contains both Lactobacillus and Bifidobacterium strains in a dose of at least 10 billion bacteria per serving.

Mushrooms are interesting too

The overall quality of your diet is more beneficial than focusing on any single food or nutrient, but mushrooms do appear to be interesting when it comes to immunity.  Not only are they one of the few foods to contain a natural source of vitamin D, but they also contain beta-glucan polysaccharides that have been shown by some studies to modulate the immune system (11).  Chinese medicine has long considered mushrooms to be medicinal and especially varieties such as shiitake.

Immunity is a hugely complex system that involves many different cells that work together to fight foreign invaders in the body.  Your diet is known to have a role to play although exactly how is yet fully understood.  Eating a balanced diet is no doubt helpful and there are certain nutrients that play a key role in maintaining the proper function of your immune system. Diet shouldn’t be defined by nutrients as food is what matters but understanding the nutrients that support your immune system help to support the importance of a balanced diet made up of a wide variety of foods.

 

References 

  1. https://www.gov.uk/government/statistics/ndns-results-from-years-7-and-8-combined
  2. https://www.ncbi.nlm.nih.gov/pubmed/11375434
  3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3173740/
  4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3723386/
  5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3724376/
  6. https://www.ncbi.nlm.nih.gov/pubmed/23440782
  7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3166406/
  8. https://www.ncbi.nlm.nih.gov/pubmed/19237723
  9. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3560336/
  10. https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD006895.pub3/abstract
  11. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4684115/

 

Vitamin D for desire?

Vitamin D for desire?

Boosting your vitamin D during the winter months may help with libido study says… (Download PDF)

Ever wondered why the summer months leave you feeling frisky and the winter makes you feel more like settling in with a warming cup of cocoa and a box set before bed? Winter has always encouraged us to get cozy and comfort eat but could our lack of the sunshine vitamin be a reason why many of us go off sex as the nights draw in?

Diet and libido

There are many factors that can affect libido such as stress, anxiety, depression, medication, smoking, drinking, illness and being overweight.  These factors can impact on the food choices we make, which in turn can affect nutrient intake and the quality of our diet.  Some can even impact on the bodys requirement for certain nutrients or affect their absorption in the body and the joint effect of this may have an impact on your libido.

What you eat could have an effect on your sex drive – and not just by providing vitamins, minerals or aphrodisiac foods. What you eat influences your hormone balance and following a hormone-friendly diet will help. This involves obtaining the right types of essential fatty acids – such as those found in oily fish, nuts and seeds, plenty of fruit and vegetables (at least five servings per day) and as wide a variety of wholegrains as possible. Wholegrains are a rich source of B vitamins, plant hormones and the trace minerals that are vital for both a healthy sex drive and for sexual stamina

 

Nutrients that are important for sex drive  

Sexual Function Nutrient Food sources
Production of sex hormones, including testosterone and maintaining sex drive Vitamin A Liver, eggs, dairy, fish, meat, dark green leafy vegetables and orange-yellow fruits and vegetables
Magnesium Nuts, seeds, brown rice, wholegrains, eggs, cocoa, dark green leafy vegetables
Slenium Brazil nuts, broccoli, mushrooms, cabbage, onions, garlic, wholegrains, seafood
Zinc Red meat (especially offal), seafood (especially oysters), wholegrains, pulses, eggs and cheese
Production of sexual secretions and fertility Vitamin C All fruit and vegetables but especially citrus, berries, peppers, kiwi and leafy greens
Vitamin E Oily fish, fortified margarine and dairy products, liver, eggs
Production of energy, stamina and staying power, plus healthy circulation and blood vessel dilation B vitamins Yeast extracts, brown rice, wholegrain bread, seafood, poultry and meat (especially offal), pulses, nuts, eggs, dairy products, green leafy vegetables
Iron Red meat (especially offal), seafood, wheat germ, wholemeal bread, egg yolk, green vegetables, prunes and other dried fruit
Arousal and orgasm Calcium Milk, yoghurt, cheese, green vegetables, oranges, bread
Phosphorus Dairy products, yeast, soya beans, nuts, wholegrains, eggs, poultry, meat and fish

 

Vitamin D and libido

Vitamin D has been a sexy nutrient for a while now and research findings exploring its many potential health benefits seem to make the headlines on a monthly basis but could this vitamin really put the D back into desire?

Research findings have suggested that the sunshine vitamin may have a key role to play in the libido of both sexes.  A study published in the journal, Clinical Endocrinology (1) has shed further light (excuse the pun) on the possible link between vitamin D and sexual desire. The research findings have found that levels of the male sex hormone testosterone may be linked to vitamin D status and that men with adequate levels of this nutrient had more testosterone that those with lower levels.  Delving deeper, researchers also found that testosterone levels dipped during the winter and peaked during the summer, implying an association between this male hormone and vitamin D. 

Women may also be affected by the lack of sunshine during the winter as it may impact on levels of oestrogen.  A study published in the Journal of International Urology and Nephrology (2) found those with sexual dysfunction had lower blood levels of vitamin D. Further research has also suggested that low levels are linked to low arousal, lubrication, orgasm, satisfaction and pain.

 

Vitamin D and mood

Low vitamin D levels have also been associated with low mood and in particularly Seasonal Affective Disorder. Vitamin D activates the genes that release of neurotransmitters, dopamine and serotonin, the lack of which is linked to depression.  Low levels of testosterone have also been shown to impact on low mood and oestrogen helps to boost serotonin and other transmitters such as GABA that promote calm and happiness.  It may be that low levels of vitamin D trigger a vicious cycle of low mood and libido that impact on your sex life during the winter months.

 

Vitamin D status in the UK

Findings from the UK National Diet and Nutrition Survey (3) have shown from blood analysis that theres evidence of low vitamin D status in 23% of adults over the year, which increases to 40% during the winter.

 

How much vitamin D do we need?

The current recommendation for vitamin D is 10mcg per day as advised by Public Health England. Many experts believe this is a minimum and in the absence of sunlight a dose of 25mcg (1000IU) may be more appropriate to maintain bone, heart, brain and immune health.  Older people may be recommended a higher dose of at least 50mcg (2000IU) as they process sunlight less efficiently through the skin and have a reduced ability to absorb vitamin D from the limited foods that contain this nutrient. 

 

Can you get enough vitamin D from your diet?

At most, its likely that you may be able to get up to 20% of your vitamin D intake from food but the rest needs to come from sunlight in the summer and supplements during the winter. Even if youre lucky enough to escape the British winter with a sunny holiday, your stores of vitamin D are not likely to last more than 4-6 weeks.

Very few foods contain vitamin D. The main source is oily fish and a little can be found naturally in eggs and mushrooms.  You can also find vitamin D in fortified foods such as breakfast cereals and margarine spreads.

 

 

Vitamin D content of foods in mcg per serving  

Food Portion size vitamin D (mcg)
Herring raw 140g 26
Sardines raw 140g 15.4
Trout raw 140g 14.8
Pilchards canned in tomato sauce 1 can 14
Kipper raw 140g 11.2
Tuna raw 140g 10.8
Salmon raw 140g 8.4
Canned salmon half a can 8
Mushrooms 100g 5
Eggs 2 eggs 1.8
Bran flakes 30g 1.3
Children’s yoghurt (petit filous) 1 pot 1.3
Flora 15g 0.75

 

Supplementing your diet

Supplementing your diet with the recommended 10mcg (400IU) is the most effective way to increases and maintain your vitamin D levels.  Increasing the dose to 25mcg (1000IU) will do you no harm and may help you to achieve optimal rather than adequate levels.  When choosing a supplement, you should opt for vitamin D3 as evidence suggests that this form is more effective at maintaining vitamin D status than vitamin D2.

 

Light therapy

If vitamin D really does impact on sex hormones and libido then another option to get your UV fix is light therapy. Scientists at the University of Siena in Italy (4) found that regular, early-morning use of a light box (such as those used to treat SAD) helped men increase testosterone levels and improved their sex life.

There are many factors that can affect libido but if ensuring your vitamin D levels has a role to play then why not try topping up with supplements, diet or explore light therapy to see if this helps to reignite the lost spark in the bedroom during the winter months.

 

References

  1. https://www.ncbi.nlm.nih.gov/pubmed/27522658
  2. https://academic.oup.com/jcem/article-abstract/102/11/4292/4096785?redirectedFrom=fulltext
  3. https://www.gov.uk/government/collections/national-diet-and-nutrition-survey
  4. https://www.sciencedaily.com/releases/2016/09/160918214443.htm

 

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