Vitamin E

Can we survive without vitamin E?

Vitamin E is a fat soluble vitamin that is essential to health. Without it we would experience problems with our nervous system. Symptoms of vitamin E deficiency include, ataxia (impaired balance and coordination), myopathy (muscle weakness), neuropathy (pain, numbness, tingling sensations) and retinitis pigmentosa (damage to the retina of the eye that normally leads to reduced night vision followed by tunnel vision followed by blindness). In other words we want our vitamin E status to be adequate. But how much is adequate, and is there any point in consuming a lot more than the recommended daily amount of 15mg?

What is vitamin E?

To begin to answer the question of whether it is beneficial to consume a lot of vitamin E we need to understand exactly what it is. Firstly it is defined as being a collection of eight different compounds. Secondly, it can be either synthetically produced or in its natural form.

The 8 compounds.

There are 8 different forms of vitamin E. They are classified as either, tocopherols or tocotrienols depending on their side chains. Both tocopherol and tocotrienol types are split further into alpha - a, beta - b, gamma - y and delta - d forms. The alpha, beta, gamma and delta are determined by what is on the spiky bits around the hexagon shaped head of the molecule. The most common form in the body is a-tocopherol, which is the form most common in the European diet, but in the US, y-tocopherol is more widely consumed. The reason we all end up with more a-tocopherol  in our body is that our liver preferentially retains it.

The significance of all these forms is that they do not have equivalent effects in the body. For instance there is evidences that tocotrienols are more effective at reducing risk of heart disease and cancer than tocopherols. Among the more common tocopherols, y-tocopherol may help prevent prostate cancer, while a-tocopherol may not. All this means that when we read about vitamin E we have to consider what exactly is being written about. Normally it is a-tocopherol, but this is not always the case.

Natural or synthetic.

Vitamin E is used as a food additive due to its anti-oxidant functions, which prevents fats from going rancid. In Europe it has the following E-numbers: E306 for natural vitamin E, E307 for synthetic a-tocopherol, E308 for synthetic y-tocopherol and E309 for synthetic d-tocopherol. Synthetic tocopherols and tocotrienols have only half as much vitamin activity as natural vitamin E compounds and are prefixed with the letters "dl-" on supplements. Natural vitamin E compounds are prefixed with "d-".

Functions.

Vitamin E is well known as an anti-oxidant that prevents damage to the membranes that surround each and every one of our body's cells. It also acts as a blood thinning agent and as such has been investigated to see if supplemental amounts reduce risk of cancer, cataracts and heart disease. Results have been mixed and this reflects a misunderstanding of the complexity of vitamin E and its antioxidant role in our bodies.

As an anti-oxidant, vitamin E neutralises reactive particles called free radicals that can cause damage in our body. These free radicals are produced by normal metabolism. They are increased in times of stress, whether from intense activity, cigarette smoke, pollution or ionizing radiation. So far, so good. However, vitamin E neutralises free radicals by becoming one itself, and it is this fact that is often overlooked in studies that supplement vitamin E. In real life when we eat foods containing vitamin E we often consume other anti-oxidants such as beta-carotene and vitamin C that help to neutralise the free radical version of vitamin E. It is the careful combination of the right anti-oxidants that is most likely to lead to benefit rather than the supplementation of a single anti-oxidant such as vitamin E.

Food sources of vitamin E.

The recommended daily amount of vitamin E is 15mg. Vitamin E is found in nuts and seeds and their oils as well as a few other foods, notably eggs, avocado pears, olives, blackberries, chocolate and green leafy vegetables1.

For a handful, 100g of nuts: almonds contain 25mg of vitamin E, hazels contain 15mg, peanuts 8mg, brazils 6mg, pistachios 2mg, pecan and cashews 1mg and walnuts and macademias about 0.6mg.

For a handful, 100g of seeds: sunflowers contain 33mg, pinenuts contain 9mg, flax, sesame and pumkin contain less than 0.3mg.

Among 100g of other foods: Margarine contains 5mg, olives contain 4mg, blackberries contain 3.5mg, avocados contain 3mg (1/2 an avocado), greens such as spinach contain 2mg, butter contains 1.5mg and eggs contain 1mg (it takes 2 small eggs to weight in at 100g). Chocolate is also around the 1mg mark.

Clearly sunflower seeds, almonds and hazels are the most potent sources with 100g of either supplying more than the recommended daily amount. Bear in mind that the recommended daily amount is a minimum ammount determined to ensure that 95% of the population do not get symptoms of deficiency. For most people consuming between 15-100mg a day could be considered a healthy range. 

Unsurprisingly the oils produced from many of the above foods are also potent sources of vitamin E. Typically the vitamin E content is about 2-3 times more concentrated than the food source. So for instance 100mg of olve oil contains  15mg of vitamin E while 100g of olive contains 4mg, However normally oils are eaten in smaller quantities. A tablespoon of oil weighs in at around 15g (dessert spoon 10ml and teaspoon 5ml).

So as stated above, you want to ensure you consume enough vitamin E. That is best achieved by ensuring you have sufficient fat in your diet as vitamin E is fat soluble and is best absorbed in the presences of fats. In particular nuts and seeds are a healthy addition to any diet. Almonds and hazels are associated with a low inflammatory index score1, which means that they contain a lot of anti-inflammatory compunds, which can be expected to improve your health. Avocados are another great food as are blackberries in season. On the other hand although you always find vegetable oils and margarines listed when you look up vitamin E. These are not foods that I recommend that you consume, as they contain trans-fats which are clearly linked with heart disease and other degenerative conditions. Their equivalents of olive oil and butter are far more healthy, and in the case of butter, have been given an unwarrented negative press over the last 30 years.

So should we supplement vitamin E?

In general I'm not a great fan of vitamin E supplementation on its own for a number of reasons.

  1. Vitamin E can become pro-oxidant and therefore potentially damaging to the body in large amounts2.
  2. Being fat-soluble, most but not all Vitamin E supplements come with an oil such as safflower oil or sunflower oil. It is rare for these oils to be free of trans fats, and as I've never seen a supplement company advertise the fact that the sunflower or safflower oils they use are unrefined, I have to assume they are not, and that they contain trans fats.
  3. In supplements or fortified foods, synthetic vitamin E is often used. It has only half the activity of natural vitamin E.
  4. Most supplements contain proportionately large amounts of vitamin E in the form of alpha-tocopherol. The other types of vitamin E are not absorbed as well in the presence of alpha-tocopherol so some of their benefits are likely to be lost.
  5. High dose vitamin E supplementation has been linked to and increase in all cause mortlity3.

Despite the above points I do think that for certain categories of people and in conjunction with other anti-oxidants supplementation of vitamin E could be beneficial.

Who benefits from supplementation.

There are categories of people for whom vitamin E supplementation could be useful, such as those with problems absorbing vitamin E from the digestive tract. This includes those with cystic fibrosis and cholestatic liver disease. Also people who choose to be on a very low fat diet where fat makes up less than 15% of total calories may benefit. Many people have done this because they think it is more healthy. It isn't!  For these people it would normally be better just to eat more fat.

How to supplement vitamin E.

You can find vitamin E supplements that contain no oil and therefore no trans fats. Some are made from the natural form of vitamin E and some with mixed tocopherols and tocotrienols added in. When it comes to risks of vitamin E supplementation the evidence isn't conclusive. We should bear in mind that high doses of vitamin E can thin the blood, and that could increase risk of internal bleeding and stroke in some people. This is the reason some vitamin E supplements have cautions not just for people on blood thinning medications, but also for people with hypertension. There is an upper limit set of 1000mg per day. However in my view people should limit supplemental intake to below 200mg unless they know thay have a problem with fat absorption.

References:

1) http://nutritiondata.self.com

2) http://www.ncbi.nlm.nih.gov/pubmed/17025373

3) http://www.annals.org/content/142/1/37.full