Due to current circumstances we are seeing more and more blogs, posts, and videos on nutrition and immune health. A lot of posts focus on ‘boosting’ your immune system with nutrients, however, it is important to note that you cannot boost your immune system, so through this blog what we will talk about is supporting your immune system. Please note, overloading your body with specific nutrients will not boost your immune system, and in some cases excess amounts of nutrients can be dangerous, or in others you just excrete excess amounts.
Vitamins and minerals play a role in helping to maintain a healthy immune system. The reason that a healthy balanced diet is usually spoken about is due to the fact that by getting a variety of foods, you are more likely to get all the vitamins and minerals that you need to help support your body. It’s also worth pointing out, that you do not need to be cutting out any foods or food groups to help your immune system, unless due to a medical or dietary reason.
Nutrients That Play a Role in Supporting Our Immune System
I’ll talk a little bit about different nutrients that play a role in the normal functioning of the immune system. This information isn’t me saying that you should go out and buy supplements of each one, so please don’t!
With a lot of things, especially if you are taking medications, is the risk of a reaction between something that you add in. Even if it is an herbal supplement you should always be cautious about adding it in. As mentioned before, some vitamins and minerals in excess amounts can be harmful and can also impact the absorption of other vitamins and minerals. Further down I will talk about side effects of taking excess supplements of each of the below.
When we talk about vitamin A, there are two versions we commonly talk about. Vitamin A (retinol) is one and is only found in animal sources such as eggs, oily fish, dairy products and liver. In pregnancy large amounts of vitamin A (retinol) can be harmful to the baby which means that supplementing with vitamin A should be avoided.
The other way that we can get vitamin A is from beta-carotene, which our body converts into vitamin A. Sources of beta-carotene includes yellow, red and green leafy vegetables and yellow fruits, including spinach, carrots, sweet potatoes, peppers, mango and apricots.
Vitamin A is a fat-soluble vitamin which means that we can store it. Excessive amounts can be harmful specifically in regard to retinol vitamin A. With beta-carotene our body will only convert as much as it needs into vitamin A retinol.
In the UK:
- Adults (19-64 years) need 0.7mg a day for men, and 0.6mg a day for women.
As well as playing a role in immune health, vitamin D helps to regulate the amount of calcium and phosphate in the body. Vitamin D is known as the sunshine vitamin, and from late March/early April to end of September, most of us should be able to get enough vitamin D from sunlight. From end of September to late March, we should all consider supplementing with Vitamin D.
- Children over the age of 1 and adults need 10mcg (micrograms) of vitamin D a day
- Children under one need 8.5mcg to 10mcg a day (through supplementation if breastfed, formulas contain vitamin D).
You may also see supplements have IU after the number instead of mcg, and in reference to this 10mcg is 400IU.
Food sources of vitamin D include oily fish, red meat, liver, egg yolks, some mushrooms and fortified foods.
Who is at risk of vitamin D deficiency and should take 10mcg of vitamin D all year round?
- Those who have little to no sunshine exposure if you aren’t often outdoors (frail, housebound)
- Those who usually wear clothes that cover up most of you skin when outdoors
- Those with dark skin may not get enough vitamin D from sunlight
During this current time, it may be worth those who are isolating, or do not have access to go outside to consider taking 10mcg.
Exposure to sunlight cannot cause you to overdose on vitamin D, however, it is important to be safe and reduce your risk of skin damage and skin cancer.
This is also known as pyridoxine, and foods which contain it include wholegrain cereals, vegetables, soybeans, peanuts, milk, potatoes, eggs, pork, fish, chicken, turkey, and some fortified products.
In the UK:
- Adults (19-64 years) need around 1.4mg a day for men, and 1.2mg a day for women
Vitamin B9 (Folate)
Folate is also known as folic acid , which is the man-made form. Sources of folate include chicken, green leafy vegetables, wholegrains, liver, broccoli, Brussel sprouts, peas, chickpeas, some fortified products.
If you could get pregnant or are trying for a baby, it is recommended that you take a 400mcg(0.4mg) folic acid supplement, until you are 12 weeks pregnant, this needs to be taken before you are pregnant.
In the UK it is recommended that:
- Adults need 200mcg(0.2mg) a day
Vitamin B12 (cobalamin) can be found in meat, salmon, milk, cheese, eggs, and in some fortified foods. If you are vegan or are vegetarian and consume little to no dairy and eggs, it is worth considering supplementation, or making sure you include fortified products.
It is recommended that we aim to get:
- 5mcg a day of B12 for adults aged 19-64
For those on a vegan diet, you should aim to get fortified foods 2-3 times a day, or supplement with either a daily 10mcg, or a weekly supplement containing 2000mcg.
Vitamin C plays a general role in immune functioning. It is not common to be deficient (think scurvy) which can play a role in reducing immune functioning. Generally, most of the population can get enough from foods, and do not require a supplement.
Vitamin C is in citrus fruits, red and green peppers, tomatoes, berries, green vegetables, and white potatoes. A systematic review found that in the general population a vitamin C supplement of 1,000mg did not reduce the frequency of the common cold. It did, however, reduce the duration by 8% (which is roughly half a day) but you would need to be taking this before symptoms of the cold started. However, please note this doesn’t mean that it works for everything.
In relation to current situations, there is no concrete data for vitamin C’s role in Covid-19.
In the UK:
- Adults ages 19-64 need 40mg of vitamin C a day, smokers should aim to get 80mg a day.
Copper can be found in nuts, seeds, soybeans, potatoes, chickpeas, shellfish and liver.
In the UK:
- Adults (19-64 years) need 1.2mg of copper a day
Sources of iron include pulses, legumes, tofu, nuts, dried fruit, meat, wholegrains, dark green leafy vegetables, seeds, oats, and quinoa. Interestingly eating vitamin C rich foods alongside iron rich foods increases the amount of iron that you absorb.
In the UK it is recommended that:
- Men over 18 need 8.7mg a day, however, women between 19-50 years need 14.8mg, and women over 50 need 14.8mg
When people think of selenium, they usually think of brazil nuts, and you can also get it from fish, meat, eggs, and brown rice.
In the UK:
- Men aged between 19-64 years need 0.075mg a day and women aged 19-64 need 0.06mg a day
You can find zinc in meat, dairy foods, bread, cereals, shellfish, beans and nuts.
In the UK:
- Men aged between 19-64 need 9.5mg a day, and for women 7mg
What About Supplementation?
Supplementation is only recommended if you are deficient in a certain nutrient, in most cases. This can vary if you are pregnant, have a medical condition (for which your doctor has recommended supplementation), are part of a certain population group, or follow a specific diet which may lead to a risk of deficiency.
Why Excess Amounts of Vitamins and Minerals Can Be Dangerous
It has been shown in some research that having an average of 1.5mg of vitamin A per day may affect your bones and increase the risk of fractures when you’re older. This is especially important for women as they are at a higher risk of osteoporosis. Be aware if taking fish liver oil as it is high in vitamin A. If you are supplementing you may want to make sure that you are getting no more than 1.5mg a day from the supplement and from food. If you eat liver every week you do not take a supplement containing vitamin A.
Too much vitamin D over a long period of time can cause a build-up of calcium in the body, which can weaken bones and damage your kidneys and heart. Do not take more than 100mcg a day as it could be harmful. 10mcg is enough unless specified by a health care professional (doctor, nurse, or dietitian).
Excess amounts of B6 (over 200mg a day) over a long period of time can actually lead to loss of feeling in your arms and legs. These symptoms can improve once the B6 supplement has stopped being taken, but in some cases, it may be permanent, especially in those who have taken it for a few months. Over short periods of time it should be fine to take 10-200mg a day, however, it is not known for how long these amounts can be safely taken.
Folic acid, when taken in higher than 1mg doses can mask the symptoms of a B12 deficiency, which can cause damage to the nervous system, if not treated.
For B12, there is not enough evidence to show what effects excess B12 may cause. It is believed that taking 2mg or less a day is unlikely to cause any harm.
For vitamin C, taking large amounts over 1000mg per day can cause stomach pain, diarrhoea, and flatulence.
Excess amounts of copper can cause stomach pains, sickness, diarrhoea, and damage to kidneys and liver (if taken in excess over a long period of time). Having 1mg or less a day of copper is unlikely to cause any harm, however, you should be able to get enough through diet.
Iron supplements should only be considered if it is something discussed with your doctor, or dietitian. Taking a high dose, over 20mg, can lead to constipation, feeling sick or vomiting, and stomach pains.
Excess selenium can cause selenosis, which can cause loss of hair, skin and nails in its mildest form. You should be able to get enough selenium in your diet if you include meat, fish or nuts in your diet. In a supplement, too much selenium can be dangerous. Taking 0.35mg or less a day is unlikely to be harmful.
Zinc, if taken in high doses, can reduce the amount of copper that your body can absorb and can cause anaemia and weaken the bones. Unless advised by your doctor, you should not be taking more than 25mg of zinc supplements a day.
You’re better off getting your nutrients from whole foods where possible.
It is too simplistic to reduce foods just down to a single component. We know that nutrients, as well as other substances like antioxidants, work together in a complex way. You can’t boost your immune system, so trying to choose as varied a diet as possible, whilst also being conscious of getting enough sleep, managing stress as best as you can, taking part in physical activity, reducing alcohol consumption, stop smoking, and washing your hands are the best ways to help support your immune system. There is no need to reach for immune boosting supplements.
If you don’t have access to fresh fruits and vegetables, you can always use frozen, or tinned varieties, which will provide you with the same nutrients as fresh. With tinned fruits and vegetables, it is better to choose versions which have no added salt or sugar. You can read more about this here.
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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