Two essential vitamins often working together are vitamins A and E. Both are fat-soluble vitamins with important roles as antioxidants. Studies continually find how these two antioxidant vitamins enrich your health and prevent certain diseases. Before we review some of the latest research, let’s take a moment to quickly review their function and status in the body.
Vitamin A Review
Vitamin A is actually the name of a category of vitamins known as retinoids, including retinol, retinal, and retinyl esters. You can consume it already formed, or you can consume provitamin A in the form of carotenoids and your body will then synthesize it into vitamin A. The most well-known carotenoid is beta-carotene, but there are other forms (i.e., beta-cryptoxanthin and alpha-carotene).
The most important functions of vitamin A in the body include:
– Cell growth and differentiation
– Communication in the cells
– Immune function
– Vision health
The RDA, or recommended intake, of vitamin A is 900 ug/day for adult males and 700 ug/day for adult females. Children, teenagers, pregnant women, and lactating women require different amounts. One of the most common symptoms of deficiency includes night blindness and other vision problems. Other signs of deficiency or insufficiency include:
– Developmental problems
– Dry skin and hair
– Infertility and miscarriage
Vitamin E Review
Vitamin E is the name for a group of fat-soluble compounds known as tocopherol and tocotrienol, with tocopherol the most important to humans. There are four types of each, labeled as alpha, beta, gamma, and delta.
The essential functions of vitamin E include:
– Cell signaling
– Immune function
– Metabolic processes
The recommended intake is 15 mg/day for adult males and females, with children, teenagers, and lactating females requiring different amounts. In one study, both smokers and non-smokers tended to have an intake below the EAR (the level that meets the needs of roughly half the population and is less than the RDA) with 98 percent of smokers and 94 percent of nonsmokers falling in this category. With so many failing to meet the EAR, it is likely even more struggle to meet the higher RDA levels.
Overt deficiency is rare, especially in healthy people, but it might occur in those who cannot absorb fat. Signs of deficiency or insufficiency include:
– Ataxia (the inability to control bodily movements)
– Immune impairment
– Peripheral neuropathy (which affects the nerves and may impair sensation and/or movement)
– Retinopathy (which can result in the loss or impairment of vision)
– Skeletal myopathy (which affects muscle cell structure and metabolism and can lead to dysfunction and weakness)
New Studies on Vitamins A & E
Although both vitamins A and E play diverse roles in the body, they have key roles as important antioxidant vitamins. Many of their health benefits come from their ability to mitigate excessive oxidative stress and prevent damage. Recent research has unearthed some exciting findings on the impact of these vitamins on health.
Consuming sufficient quantities of vitamin A and E might help prevent cancer development. In a prospective study published in October 2017, there was an inverse association between vitamin E dietary and total intake with digestive cancer risk. Former smokers and people who had never smoked had a more significant reduced risk than smokers associated with vitamin E intake. The study found a similar correlation between dietary and total intakes of selenium and vitamin C but not beta-carotene. Despite the overall finding, the researchers found no association between taking supplements of these antioxidant vitamins and digestive cancer risk.
A recent meta-analysis found that vitamin E might be protective against colorectal cancer, which is one of the most common cancers. The researchers reviewed 11 studies meeting their rigorous inclusion standards for a total of 6,431 subjects, 520 of which were cases and the remaining 5,981 as controls. Those who had colorectal cancer had lower levels of vitamin E in their blood, with the pooled effect size -2.994 umol/L.
In another study, the researchers found an inverse correlation between plasma alpha- and beta-carotene levels, with a 39 to 59 percent reduction in risk of ER- breast cancer.
A Healthy Gut
Vitamin A and E intake might also influence gut bacteria. In a study on patients with cystic fibrosis, the researchers found that intake of potassium, vitamin C, vitamin E, beta-carotene equivalents, and niacin equivalents had an inverse association with Bacteroides. Conversely, the intakes of many of the same nutrients had a positive correlation with Firmicutes, which might imply that micronutrients could impact the makeup of the gut microbiome. The researchers hypothesize this might be due to their impact on the gut environment, such as reducing mucus production, or it might be due to their antioxidant characteristics.
Obesity and Metabolic Syndrome
A case-control study found a relationship between vitamin A and E levels and metabolic syndrome. There was a significantly lower level of vitamins A and E, as well as C, in those with metabolic syndrome compared to the control. Deficiency based on plasma markers was 15.38 percent of metabolic syndrome patients for vitamin A, 60.45 percent for vitamin E, and 79.12 percent for vitamin C. There was also an inverse correlation between diastolic blood pressure and vitamin E levels and a positive correlation between the vitamin and HDL. Vitamin A also had a positive correlation with HDL cholesterol.
In this study, the dietary consumption was not that different between the patients and the controls. The researchers postulate that this could correlate to the higher oxidative stress levels shown to exist in those with metabolic syndrome and obese subjects in other studies, as well as the fact that higher levels of adipose tissue might lead to more stored fat-soluble vitamins rather than circulating vitamins.
Another study found that consuming the antioxidant vitamins led to a lower risk of obesity even in those who have a short sleep duration, which is associated with a higher obesity risk. In this study, the odds of obesity were 1.467 (95% CI 1.282 – 1.678) in those who slept for shorter durations. Those who slept at or above 7 hours a day had no increased risk of obesity, regardless of their antioxidant intake. However, those who slept six hours per day or less had a reduced odds ratio with higher levels of vitamins A, C, and E, although the odds ratio was still above 1, meaning there is still an increased risk of obesity.
Although many studies have shown little to no advantage of supplementing with vitamins A and E, one study did find a benefit in supplementation with lowering the risk of developing metabolic syndrome. According to data from the KNHANES, which assess health and nutritional status of Koreans, the highest tertile of vitamin A and E intake had a significant reduced prevalence of metabolic syndrome, with an OR of 0.72 for vitamin A and 0.74 for vitamin E (both at 95% CI 0.53 – 0.99 and 0.55 – 0.99 respectively). For dietary supplement users in general, the odds ratio was 0.82 (95% CI 0.68 – 0.98). Supplementation did increase the total antioxidant intake in the participants, contributing about 38 percent of the total antioxidant capacity. However, this finding might be confounded by the fact that many supplement users tend to live a more healthy lifestyle.
Inflammation and Immune Response
Both vitamins A and E play a role in facilitating a strong immune system, and a deficiency could cause immune-related issues. In one study, researchers found a link between serum levels of vitamin A and E, as well as D, and certain immune-related disorders. Through using samples from tonsils removed from tonsillectomy patients, as well as serum samples taken prior to the surgery and a questionnaire to determine the history of certain diseases and allergies, the researchers looked for correlations. They found that higher vitamin E levels related to lower prevalence of allergy, while higher vitamin A levels correlated to fewer detections of viruses and higher expression of IFN-gamma in the tonsils, demonstrating it might have anti-viral effects.
Deficiency or insufficiency of vitamins A and E might also increase the risk of developing recurrent respiratory tract infections in children. Researchers reviewed data in China and found an inverse relationship between serum levels of the vitamins, as well as vitamin D, and recurrent infections. In the control group, the incidence of deficiency or insufficiency for the vitamins was 24.33 percent, 8.17 percent, and 19.33 percent for vitamins A, E, and D respectively. For those with recurrent infections, the percentage of deficiency or insufficiency was 63 percent, 33.83 percent, and 56.50 percent for vitamins A, E, and D respectively.
In pre-pubescent girls in Spain, a lower intake of vitamin A and E, as well as fiber, had a higher hs-CRP level, which is a marker for inflammation. There was a corresponding decrease in the fruit and vegetable intake in the highest tertile for hs-CRP. Thus, consuming these vitamins, especially if intake comes from vegetables and fruit, might help reduce inflammation, which might also prevent some of the chronic conditions associated with chronic inflammation.
The brain also requires sufficient levels of vitamins A and E. In one study, researchers found potential protective benefits of vitamins A and E: the ability to lower the risk of developing Parkinson’s disease (PD). Using data from the Swedish Mammography Cohort and the Cohort of Swedish Men, the researchers reviewed intake of dietary antioxidants using a 96-item food frequency questionnaire. They calculated the average intake of vitamins C, E, and beta-carotene, a precursor of vitamin A. They compared this to whether patients developed PD over time. They found that those who had higher levels of dietary antioxidant vitamins had a lower risk of PD. In both men and women, there was an inverse association between beta-carotene intake and PD, while this was only present in women for vitamin E and vitamin C.
It is not just PD. In patients with non-Alzheimer’s type dementia, researchers found a significant correlation between low serum levels of vitamins A and E, as well as elevated levels of homocysteine, and the risk of developing the disease.
Other Health Benefits
Another way the antioxidant capacities of vitamins A and E might help is to prevent hearing loss. In a prospective study reviewing the data from the Nurses’ Health Study II, researchers compared responses to self-reported hearing loss and intake of carotenoids, vitamins A, C, and E, and folate in multiple years of the study using a detailed semiquantitative food-frequency questionnaire (sFFQ) with more than 130 items. The participants filled out the sFFQ every four years between 1991 and 2007. During a 2009 questionnaire, they responded to whether they had a hearing problem and at what age it began. Higher intakes of carotenoids, especially beta-carotene and beta-cryptoxanthin, as well as folate, had an inverse association with hearing loss. Vitamin C had a positive correlation with an increased risk of hearing loss. Vitamin E had no significant trend, although there was a minor positive association.
Antioxidant capacity plays a role in maintaining reproductive health in women, so having sufficient intake of vitamins A and E, as well as other antioxidants, might be an important component of women’s health. In one prospective cohort study looking at healthy, menstruating women, researchers found a variance in antioxidant level during the phases of menstrual cycle. During menses, the levels of retinol, alpha-tocopherol, lycopene, lutein, beta-carotene, and ascorbic acid were lower compared to the different phases. There was also a positive correlation between E2 and testosterone and several of these antioxidants, including retinol, lutein, and alpha-tocopherol. There was a positive association with LH and retinol and a negative association with FSH and alpha-tocopherol and ascorbic acid. There was also a correlation between a higher alpha-tocopherol to gamma-tocopherol ratio and an increased risk of anovulation, demonstrating the importance of mixed tocopherols.
How to Ensure You Have Adequate Levels
It is generally best to start with food to ensure adequate intake levels of nutrients, including vitamins A and E. By recognizing the richest sources of these vitamins, you can easily add them to your daily diet to boost your general intake and reduce your risk of deficiency.
Food Sources of Vitamin A
Vitamin A precursors are found in a variety of plant-based foods, making it easy to consume copious amounts. Below is a chart of the foods richest in the different forms of vitamin A, listed from greatest to least:
Cod liver oil
Other leafy greens
As you can see, some foods make it on several of these lists, so they are a great place to start for loading up on vitamin A.
Food Sources of Vitamin E
Some of the foods richest in vitamin E, in order from greatest to least, include:
– Sunflower seeds
– Pine nuts
– Rose hips
– Dried apricots
– Sunflower oil
– Almond oil
As you can see from the list, nuts and seeds are a great place to start for getting your daily dose of vitamin E.
One way to enhance your absorption of vitamin E is to eat cooked whole eggs. According to one study on young, healthy men, eating a cooked egg with a salad increased the absorption of the alpha- and gamma-tocopherol from the salad at a 7.5 and 4.5 fold increase respectively when compared to eating the salad without the egg. Participants also had a higher vitamin E level after consuming the salad and egg combination than when eating the eggs alone. The increased level of absorption was higher than would be expected from just the increased intake of vitamin E from the combined food sources.
You can also increase not just your vitamin A and E level but also your overall antioxidant capacity by consuming sesame seeds. In one study on male, semi-professional soccer players, consuming two tablespoons (40 grams) of a sesame seed paste made from 40 g of crushed roasted sesame seeds mixed with 17 g of honey each day before and after training for 28 days led to an increased antioxidant capacity, including increased biomarkers of vitamins A and E, compared to the control group taking the placebo. The two groups had a similar nutritional intake, with both groups exhibiting a deficiency prior to the start of the program in vitamins A and E. The experimental group had improved oxidative stress markers and reduced muscle damage markers, with a 25 percent and 65 percent increase in serum vitamin A and E respectively.
Supplementing: What You Need to Know
Taking supplements might help reduce the risk of a nutrient deficiency or insufficiency. In one study reviewing data from the NHANES 2009 – 2012, the researchers looked at the prevalence of inadequacy in participants, comparing those getting their micronutrients from just food and those who also supplement. They found, in general, taking supplements did reduce the number of people below the EAR for some of the most commonly deficient vitamins. For vitamin A, 32.5 percent of the population had an intake that was below the EAR, while only 2.34 percent were below the EAR with supplementation. Vitamin E also had an impressive reduction, with 80.4 percent below the EAR from food intake only and 5.96 percent sufficient with supplements. For vitamin A, 0.37 percent of supplement users ended up with an intake above the upper limit, while 0 percent did for vitamin E. Food only did not put them above the UL for most of the nutrients, including vitamins A and E.
This study used the EAR, which as discussed only covers the needs of half the population. It did review some biomarkers to determine the impact of supplements, although it only looked at biomarkers for iron, vitamin D, vitamin C, vitamin B6, and vitamin B12. They did find that compared to food only intake, those who consumed the supplements did have a reduced risk of deficiency for all but iron, with the most frequent usage having a 58 to 76 percent reduced risk. A meta-analysis did point to some potential benefits of supplementing with vitamin E, especially in regards to preventing cardiovascular disease, but more studies are needed.
Both vitamin A and E are fat-soluble vitamins, which means there is a risk of toxicity for most people if you take quantities above a certain level. The tolerable upper intake designated by the Food and Nutrition Board of the Institute of Medicine for vitamin A is 3,000 ug/day for adults, with different levels for children and teenagers. For vitamin E, that number is 1,000 mg/day, with again a different number for children and teenagers.
When supplementing with vitamins A and E, you have a choice for the type you supplement. For vitamin A, you can choose to supplement with the precursors, such as beta-carotene, or the preformed vitamin A. For vitamin E, many supplements only have alpha-tocopherol. However, some studies are pointing to a potential benefit of choosing supplements with mixed tocopherols instead, at least in some situations.
As always, discuss supplementing with your doctor before you begin to go over any individual risk factors you might have. Always start increasing your intake of vitamins with a food-first approach, recognizing that supplements can help give you a boost, especially when you are deficient, but should not constitute the only source of the vitamins. When you consume food, you gain the benefit of the other micronutrients and phytonutrients in the food that act synergistically to keep you healthy!
Rainbow Foods & Supplement Course
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