In the low-fat era of the '90s, eggs were pushed aside like yesterday's leftovers. Scares of high cholesterol and heart disease made people shun the egg, or at least the egg yolk, but since then, researchers have learned that eggs are actually nutritious foods that are one of the highest biotin sources in the diet.
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Biotin is a B vitamin that plays vital roles in food metabolism and keeps your hormones healthy. But it's not just the biotin that makes eggs stand out. Eggs contain every nutrient except for vitamin C and including them in your diet can help you meet all of your nutrient needs.
What Is Biotin?
There are two classes of vitamins: fat-soluble and water-soluble. Fat-soluble vitamins dissolve in fat before being stored in your body. As the name implies, water-soluble vitamins are carried through your system by water. Biotin, also called vitamin B7 or vitamin H, is a water-soluble vitamin that belongs to the B vitamin family.
Biotin's most notable role is as a cofactor for the enzymes that help your body metabolize the carbohydrates, proteins and fats that you eat. In other words, you need biotin so that certain chemical reactions in your body can take place. It also keeps your endocrine system, or the collection of glands that produce and release hormones, healthy. Biotin is specifically involved in the action of your pancreas, thyroid and adrenal glands.
The vitamin is also often hailed for its ability to promote nail and hair growth and keep the skin healthy; although a review published in Skin Appendage Disorders in April 2017 notes that the jury is still out on this. Although there have been some studies, such as those discussed in the November 2017 review in the Journal of Dermatological Treatment, that have found promising results for treating nail conditions, the majority of studies are small and limited, and bigger clinical trials are needed to make conclusive statements.
Biotin in Eggs
A single, large egg contains between 13 and 25 micrograms of biotin. The biotin in an egg is found mostly in its yolk, so if you're trying to include more biotin in your diet, make sure you're not opting for an egg white omelet over eating the whole egg.
The amount of biotin you'll absorb from the egg also depends on whether it's raw or cooked. Raw eggs contain a protein called avidin that binds to the biotin and makes it nearly impossible for your body to absorb. Cooking the egg denatures, or destroys, avidin and releases biotin so that you can properly absorb it in your digestive tract. Once biotin is released from avidin, almost 100 percent of it is absorbed.
Eating raw eggs can increase your risk of developing a biotin deficiency, because the avidin not only binds to the biotin in the egg, it binds to vitamins from other food sources, too.
Read more: 10 Easy Ways to Cook Eggs
Other Biotin Sources
In addition to eggs, there are several other food sources of biotin. Some of the richest sources are:
- Beef liver
- Sunflower seeds
- Sweet potato
The NIH Office of Dietary Supplements notes that the exact amount of biotin in foods can vary based on the season, planting conditions and types of processing. For example, canning can reduce the biotin content in tuna, whereas eating it fresh from the ocean may provide higher amounts.
Biotin and Your Bacteria
In addition to the biotin you get from your diet, the bacteria that naturally live in your gut make some biotin, too. According to a June 2016 report in the International Journal of Trichology, the bacteria actually produce more biotin than you need for the entire day.
However, Michigan Medicine notes that there's conflicting evidence about whether or not the biotin produced by your gut bacteria is in a form that you can actually absorb. Because of this disparity, it's best to meet your biotin needs with eggs and other foods that offer forms of the vitamin that are easily absorbed.
How Much Biotin You Need
Unlike fat-soluble vitamins, your body cannot store water-soluble vitamins. Because of this, it's important to meet your needs of water-soluble vitamins every day to prevent deficiencies. Both male and female adults need 30 micrograms of biotin each day. If you're breastfeeding, that number jumps to 35 micrograms daily. Because one large whole egg is rich in the vitamin, you can meet your daily needs just by eating two to three eggs.
According to the National Institutes of Health Office of Dietary Supplements, most people get all of the biotin they need regularly. In fact, biotin deficiency is so rare, that it has never been reported in someone who was eating a normal diet that includes a variety of different foods. However, an August 2017 report in the Journal of Nutrition notes that it's possible that someone may not be getting enough biotin even if that person is not considered actually deficient.
If biotin deficiency does develop, it can cause a cluster of symptoms that may seem unrelated, like:
- Thinning hair/loss of scalp and body hair
- Rash around the eyes, nose and mouth
- Skin infection
- Brittle nails
Read more: Signs of Too Much Biotin in Your System
A Note From the FDA
Biotin is often described as "beauty vitamin" because of its connection to healthy skin, hair and nails. Many health and beauty supplements and products marketed toward strengthening the hair or promoting nail growth contain synthetic forms of biotin as an added ingredient.
In November 2017, the Food and Drug Administration issued a safety warning alerting the public that taking supplemental biotin may interfere with the results of certain lab tests. High doses of biotin can cause false highs or false lows on potentially serious tests, like one that measures troponin, a compound that can give doctors clues about your risk of having a heart attack.
This negative effect was seen only in those who were taking supplemental doses of biotin that were 650 times higher than the recommended daily intake. It's not a concern if you're getting your daily biotin from eggs or other dietary biotin sources.
- International Food Information Council Foundation: "What Is Biotin?"
- Skin Appendage Disorders: "A Review of the Use of Biotin for Hair Loss"
- Journal of Dermatological Treatment: "Biotin for the Treatment of Nail Disease: What Is the Evidence?"
- Oregon State University: Linus Pauling Institute: Micronutrient Information Center: "Biotin"
- University of Michigan: Michigan Medicine: "Biotin"
- Biotin and Other Inferences in Immunoassays: "Chapter 2 - Biotin: Pharmacology, Pathophysiology, and Assessment of Biotin Status"
- International Journal of Trichology: "Serum Biotin Levels in Women Complaining of Hair Loss"
- National Institutes of Health: Office of Dietary Supplements: "Biotin"
- The Journal of Nutrition: "Biotin: From Nutrition to Therapeutics"
- Nutricion Hospitalaria: "Role of Eggs Consumption in Women at Different Life Stages"
- U.S. Food and Drug Administration: "The FDA Warns That Biotin May Interfere With Lab Tests: FDA Safety Communication"