Did you know DNA influences your risk of vitamin E deficiency?
Vitamin E, antioxidants and genes
Skin, hair, heart and brain – it can benefit them all. Whether you chose to slather on the oil, or swallow a bright, yellow capsule, vitamin E is an extremely versatile nutrient. However, vitamin E intake is a double-edged sword. Too much or too little of it can have adverse effects on our health. We can control how much of this vitamin is in our diet, but the amount utilized by the body is beyond our control. Nutrient intake is governed by genetics, and genetic variants in the APOA5 gene are linked to variations in vitamin E levels.
Vitamin E refers to a group of fat-soluble nutrients known as tocopherols and tocotrienols. Alpha-tocopherol is the most active form in the body. It functions to promote the immune system, muscle growth, healthy eyes and skin. This vitamin is also an antioxidant, a substance that lowers the production of reactive oxygen species (ROS). When food is broken down by the body to provide energy, ROS are produced as a natural byproduct. If left unchecked, ROS can damage cells, contributing to diseases like cancer and cardiovascular disease. Studies have shown that alpha-tocopherol can control the production of ROS when fats are broken down. Hence, there is tremendous interest in researching how this vitamin may promote our general health and perhaps even extend our lives.
Vitamin E has been proposed as both a preventative aid, and a treatment option for chronic diseases, like cancer, diabetes and cardiovascular disease. However, genetic variation, (small changes in the DNA that exists between people), in the APOA5 gene can influence vitamin E levels. The APOA5 gene encodes an apolipoprotein necessary to regulate the levels of triglycerides, or storage fats. People with the rs12272004 C variant of APOA5 may have lower levels of alpha-tocopherol. This contributes to a higher risk of vitamin E deficiency, and diseases associated with ROS. Several other variants of APOA5 are also implicated in obesity, metabolic syndrome and elevated triglycerides. With its involvement in fat transport, it’s not surprising that APOA5 is one of the biggest risk factors associated with coronary artery disease.
If you are taking alpha-tocopherol supplements, you should know that when it comes to intake, moderation is key. Regularly consuming more than the allotted 1000 mg per day for an adult is actually harmful. Excess levels may cause you to experience weakness, blurred vision, dizziness, nausea and diarrhea. Excess levels are also linked to prostate cancer and increased risk of bleeding. See table at the end of this article for tolerable upper intake levels for each age group.
Nuts, leafy green vegetables, avocado, canola oil and flaxseed oil all have high levels of vitamin E. Two tablespoons of peanut butter has 3 mg of vitamin E – nearly a fifth of the 15 mg recommended daily intake for an adult. In fact, just one tablespoon of wheat germ is all you need to meet your daily requirement. More details on vitamin E-rich foods and recommended dietary allowances can be found at the end of this article.
A poor diet rarely leads to vitamin E deficiency, but there are a few instances when it can happen. Fats from our diet are essential for proper vitamin E absorption in the gut. This means that people with conditions affecting fat absorption, like Crohn’s disease and liver disease, can become deficient. There is also a rare genetic condition, isolated vitamin E deficiency, which affects fat metabolism. People with this disease have a defective alpha-tocopherol transfer protein and can’t absorb vitamin E. Symptoms associated with deficiency include muscle weakness, gross lack of coordination of muscles, paralysis of the extra-ocular muscles involved in eye movement, fragile red blood cells, anemia or the lack of healthy red blood cells, neurological problems, damage to the retina and an impaired immune system. Luckily, vitamin E supplements can counteract many of these symptoms.
History tells us that we have always had a love-hate relationship with vitamin E. From its wide popularity in the age of antioxidants to when it appeared to increase the risk of dying, vitamin E has received both praise and scrutiny. With its link to disease and evidence of protection from ROS, is vitamin E due for another revival? Judging from the growth of market shares, the answer might be yes. Whether or not you choose to jump on the supplement band-wagon, you may first want to test your APOA5 genotype, because vitamin E is a prime example of how too much or too little of something good is actually a bad thing.
Recommended dietary allowances for vitamin E (alpha-tocopherol).
Recommended dietary allowances are listed as both milligrams (mg) and international units (IU). For infants from birth to 12 months, an adequate intake is shown, which is equivalent to the mean intake of vitamin E in healthy, breastfed infants.
|0–6 months||4 mg (6 IU)||4 mg (6 IU)|
|7–12 months||5 mg (7.5 IU)||5 mg (7.5 IU)|
|1–3 years||6 mg (9 IU)||6 mg (9 IU)|
|4–8 years||7 mg (10.4 IU)||7 mg (10.4 IU)|
|9–13 years||11 mg (16.4 IU)||11 mg (16.4 IU)|
|14+ years||15 mg (22.4 IU)||15 mg (22.4 IU)||15 mg (22.4 IU)||19 mg (28.4 IU)|
Selected foods sources of vitamin E.
The Daily Value (DV) for vitamin E is 20 mg for adults and children age 4 and older. This DV was developed by the U.S. Food and Drug Administration (FDA) to help consumers compare the nutrient contents of products within the context of a total diet.
|Food||mg per serving||Percent DV|
|Wheat germ oil, 1 tablespoon||20.3||100|
|Sunflower seeds, dry roasted, 1 ounce||7.4||37|
|Almonds, dry roasted, 1 ounce||6.8||34|
|Sunflower oil, 1 tablespoon||5.6||28|
|Safflower oil, 1 tablespoon||4.6||25|
|Hazelnuts, dry roasted, 1 ounce||4.3||22|
|Peanut butter, 2 tablespoons||2.9||15|
|Peanuts, dry roasted, 1 ounce||2.2||11|
|Corn oil, 1 tablespoon||1.9||10|
|Spinach, boiled, ½ cup||1.9||10|
|Broccoli, chopped, boiled, ½ cup||1.2||6|
|Soybean oil, 1 tablespoon||1.1||6|
|Kiwifruit, 1 medium||1.1||6|
|Mango, sliced, ½ cup||0.7||4|
|Tomato, raw, 1 medium||0.7||4|
|Spinach, raw, 1 cup||0.6||3|
|Sweet potato, 1 tablespoon||4.2||15|
|Palm oil, 1 tablespoon||2.2||11|
|Butternut squash, 1 cup||2||7|
|Trout, 3 ounces||2||7|
|Olive oil, 1 tablespoon||2||7|
|Avocado, cubed 1 cup||3.1||15|
|Shrimp, 3 ounces||1.9||9|
|Sockeye salmon, 2.5 ounces||2||7|
|Swiss chard, cooked, ½ cup||2||7|
|Egg, cooked, 2 large||2||7|
Tolerable upper intake levels for vitamin E.
|1–3 years||200 mg (300 IU)||200 mg (300 IU)|
|4–8 years||300 mg (450 IU)||300 mg (450 IU)|
|9–13 years||600 mg (900 IU)||600 mg (900 IU)|
|14–18 years||800 mg (1,200 IU)||800 mg (1,200 IU)|
|19+ years||1,000 mg (1,500 IU)||1,000 mg (1,500 IU)|
Recommended dietary allowances, food sources and tolerable upper limits are obtained from the Vitamin E Fact Sheet for Health Professionals (National Institutes of Health).