In this article:
- Women are becoming increasingly conscious of the food they eat and how it affects their bodies.
- Vitamins are needed in minimal amounts but are essential for optimal health.
- Men and women are not built the same and therefore have different nutrient requirements.
- Nutrition needs are often increased during pregnancy and lactation.
- A well-balanced diet can adequately provide all essential vitamins.
Nutrition Through the Life Cycle
Nutritional needs evolve depending on the unique changes that both genders encounter in each life stage.
As people age, they experience hormone fluctuations, body composition changes, significant life events, activity variations, etc. Diet must be modified as bodies and lives change. Women experience life stages differently than men due to biological, cultural, and social differences.
In infancy and childhood, the nutritional requirements of males and females are very similar.
In adolescence, hormonal and physical changes associated with puberty start to differentiate men and women.
Women are, on average, smaller and have a lower muscle mass compared with men. Therefore, the calorie needs of women are typically lower.
However, nutrient needs are often the same or even higher for women! This means it is crucial that women consciously choose nutrient-dense foods.
The Recommended Daily Allowance (RDA) represents the level of daily nutrient intake that will meet the needs of 98% of healthy individuals. It is used to assess an individual’s diet adequacy.
The RDAs include recommendations for men and women. Usually, these recommendations are the same; however, there are a few notable differences.
What Are Vitamins?
Vitamins are nutrients that are essential for the body to function properly. Most body processes require at least one vitamin.
Although they are needed in only milligram (mg) or microgram (mcg) amounts, you cannot live without them. You cannot grow, digest, make energy, or move.
Much of what is known about the functions of vitamins first came from observing deficiency diseases among groups with low-quality diets. People used to believe that some of these diseases were due to infections.
Now, the symptoms of vitamin deficiency can be easily identified. The treatment is simple-eat more of that vitamin! Apart from vitamins D and K, the body cannot make vitamins.
They must be supplied in the diet. Eating a nutritious diet is the best way to avoid vitamin deficiencies.
This article will review the general characteristics, food sources, functions, deficiency, and toxicity diseases of the 13 essential vitamins. Additionally, it will discuss the importance of these vitamins to women’s health.
Types of Vitamins
Vitamins can be classified into two main categories:
The solubility of a substance is determined by its chemical structure. Fat-soluble vitamins can interact with fats, whereas water-soluble vitamins interact better with water. Fat-soluble substances repel water, and vice versa.
The solubility of a vitamin determines some of its general characteristics and how it acts in the body.
a. Fat-soluble: Vitamins A, D, E, and K
Fat-soluble vitamins must be escorted in the bloodstream by a carrier. They easily move into cells through the fatty cell membrane. Because a carrier must take them around the body, they are not readily excreted in the urine.
Fat-soluble vitamins can be stored in the body. If consumed in excess, they may accumulate and cause toxicity symptoms.
Toxicity rarely occurs from eating foods rich in vitamins, but from taking supplements that provide greater than 100% the daily value. Taking supplements of these vitamins can be dangerous.
b. Water-soluble: Vitamin C and B vitamins (thiamine, riboflavin, niacin, pantothenic acid, B6, biotin, folate, and B12)
Since humans are made up of 60% water, these vitamins are easily transported around the body. They travel in the bloodstream to various tissues. If not used right away, they simply are filtered out by the kidneys and excreted in the urine.
Our bodies usually do not store excess water-soluble vitamins. For this reason, toxicity is unlikely. This also means that these vitamins must be eaten regularly.
Vitamins for Women’s Health
Women need all 13 essential vitamins. Each performs a different function, and they work together to promote optimal health. The absence of even one vitamin can lead to serious health complications.
1. Vitamin A
- Recommended Amount: The RDA for adult women is 700 mcg/day. Recommendations increase for women who are pregnant (770 mcg) and lactating (1,300 mcg). During lactation, women need more vitamin A than adult men (900 mcg).
- Functions: Vitamin A plays an important role in cell growth, replication, and building new body tissues. It also helps maintain tissues that constantly make new cells, such as the skin, bones, and mucous membranes.
Infection-fighting white blood cells rely on vitamin A to maintain a healthy immune system.
Rhodopsin is a form of vitamin A that is found in the retina of the eye. It helps the brain interpret images in the dark. Without adequate vitamin A, you will not be able to see at night.
Beta-carotene is a provitamin that can be converted to vitamin A in the body. Beta-carotene has the additional benefit of being an antioxidant.
As an antioxidant, it helps prevent cell damage that contributes to diseases, including cancer and heart disease.
- Deficiency: Although not common in developed countries, vitamin A deficiency can cause xerophthalmia, commonly known as night blindness. Individuals with diseases that interfere with fat absorption are at increased risk for vitamin A deficiency.
- Toxicity: Vitamin A is stored in the liver; therefore, toxicity can interfere with liver function and can cause irreversible liver damage. Other side effects include reduced bone density, blurred vision, and hair loss.
- Food Sources: Vitamin A is high in fortified dairy products and cereals, liver, and fish. Beta-carotene is found in orange fruits and vegetables and dark leafy green vegetables.
- Importance for Women: Vitamin A is important during pregnancy and lactation because these are times of rapid cell division and growth for the fetus and mother.
However, large supplements are not recommended during pregnancy because they may increase the risk of birth defects.
Accutane is a vitamin A derivative used to treat severe acne. This drug is contraindicated during pregnancy. Women considering taking Accutane should first be tested to ensure they are not pregnant.
2. Vitamin D
- Recommended Amount: The RDA for women 14-70 years old is 600 IU per day. The recommendation increases for women over 71 to 800 IU per day.
- Functions: Vitamin D works with calcium to build and maintain strong bones. Calcium is a mineral that is used to make bones. Vitamin D controls how much calcium is absorbed from food, how much is excreted in the urine, and how much is incorporated into bones.
Vitamin D helps to maintain a healthy balance of calcium all over the body so that the right amount can be used to make bones strong.
- Deficiency: Inadequate vitamin D causes bones to soften. This is of particular concern for growing children. Vitamin D deficiency in children is known as rickets.
Rickets is characterized by the curved, bowed legs of children with bones that are not strong enough to hold the body upright.
In adults, vitamin D deficiency is known as osteomalacia, which increases the risk of fractures. (1)
Research is beginning to show that vitamin D plays a role in many diseases not associated with bones, including diabetes, heart disease, obesity, autoimmune disorders, and cancer. (2)
In pregnancy, a deficiency is associated with complications such as pre-eclampsia, gestational diabetes, infections, and low infant birth weight.
More research is needed to show the true effect of vitamin D on these diseases. However, many experts believe the RDA for vitamin D should be increased due to its relationship to many chronic diseases.
- Toxicity: Excess vitamin D can cause too much calcium to build up in the blood. If this occurs for a long period, calcium will start to deposit in the organs. This can interfere with organ function and can cause painful kidney stones.
- Food Sources: Fatty fish, liver, cheese, and egg yolks are among the few natural sources of vitamin D. Many dairy products and breakfast cereals are fortified with vitamin D and can also contribute to daily intake.
Vitamin D is one of the few vitamins that the human body can produce. Skin cells convert cholesterol to vitamin D when exposed to UV light from the sun. You only need about 10-30 minutes of direct sun exposure several times a week to produce adequate vitamin D.
However, many people face barriers that prevent them from making enough vitamin D. These barriers include limited outdoor activity, clothing that covers the body, sunscreen, and dark-colored skin.
- Importance for Women: Women are four times more likely to have osteoporosis than men. (3) This disparity is related to the average lower body weight, calcium intake, and hormonal changes that occur during menopause.
Unfortunately, bone density inevitably declines when menstruation ends. Adequate calcium and vitamin D intake is essential for women beginning in childhood to minimize the effects of this decline.
3. Vitamin E
- Recommended Amount: The RDA for women older than 14 years old is 22 IU per day.
- Functions: Free radicals are harmful substances produced during normal body processes that can damage body cells. Vitamin E is an antioxidant that blocks the harmful effects of free radicals.
Vitamin E is a blood thinner and prevents excessive clotting. Vitamin K helps blood to clot. Vitamin E and K work together to maintain a healthy balance of clotting and thinning blood.
- Deficiency: Too little vitamin E can cause excessive blood clotting. Vitamin E deficiency is not common. However, it does occur in people with disorders that prevent fat absorption.
- Toxicity: Too much vitamin E can interfere with blood-thinning medications. People who are taking warfarin or other blood thinners should have a consistent intake of vitamins E and K to maintain a desirable blood thickness.
- Food Sources: Vitamin E is high in vegetable oils, nuts and seeds, whole grains, and dark leafy green vegetables.
- Importance for Women: Some research shows that vitamin E is a beneficial antioxidant for the prevention of adverse pregnancy outcomes. (4) Adequate intake may decrease the risk of birth defects, miscarriage, and premature delivery related to stress from toxins and pollutants.
More research is needed to understand the relationship between antioxidants and pregnancy outcomes fully. (4)
4. Vitamin K
- Recommended Amount: The RDA for women 19 years old and older is 90 mcg/day.
- Function: Vitamin K helps blood to clot, preventing excessive bleeding after being cut. It also plays a role in bone metabolism.
- Deficiency: Low intake of vitamin K prevents blood from clotting properly. Deficient people may bruise easily and heal slowly from cuts. A vitamin K deficiency may also contribute to osteoporosis and cardiovascular disease. (5)
- Toxicity: Toxicity is unlikely from consuming foods rich in vitamin K. However, supplements have been known to cause hemolytic anemia-the accelerated destruction of red blood cells.
Individuals taking the drug warfarin must be cautious about including foods with vitamin K in their diet. Warfarin is a blood thinner, and vitamin K can decrease its effectiveness.
If taking warfarin, it is important to have your doctor monitor the time it takes for your blood to clot (INR) to determine the correct warfarin dose and acceptable vitamin K intake.
- Food Sources: The best food sources of vitamin K are dark leafy green vegetables. Other foods contain small amounts such as vegetable oils, some meat, and cheeses. One form of vitamin K is produced by bacteria living in the human intestines. (6)
- Importance for Women: Vitamin K has a positive effect on bone health. Low vitamin K intake has been associated with decreased bone density and increased fracture risk in women. (7)
1. Vitamin C
- Recommended Amount: The RDA for adult women is 75 mg.
- Functions: Vitamin C helps the body build and repair tissue. It facilitates the formation of collagen, a protein that maintains the stability of the skin, gums, hair, and nails. (8) Additionally, vitamin C is an antioxidant and supports eye health.
Vitamin C is touted for its immune-boosting benefits. Although vitamin C is important for immune system health, taking vitamin C above the RDA is not proven to decrease the duration or severity of cold symptoms. (9)
Research does not support taking vitamin C greater than the RDA to improve immunity.
- Deficiency: A severe deficiency of vitamin C, known as scurvy, impairs tissue repair, and wound healing. Symptoms include tooth loss, severe bleeding and bruising, fatigue, and joint and bone pain.
Vitamin C deficiency is rare because only a tiny amount of this vitamin is needed to prevent scurvy. (10)
- Toxicity: Contrary to popular belief, high doses of supplements do not enhance the functions of vitamin C. Because it is water-soluble, excess vitamin C is not stored in the body, but is readily excreted in the urine.
Supplements>2,000 mg can cause stomachaches and diarrhea.
- Food Sources: Vitamin C is high in many fruits and vegetables, including citric fruits, bell peppers, strawberries, tomatoes, cantaloupe, kale, and papaya.
- Importance for Women: Due to blood loss during menstruation, women of childbearing years need more than twice the amount of iron recommended for men (18 mg/day vs. 8 mg/day)! The recommendation is further increased to 27 mg/day for women who are pregnant.
Many women struggle to meet the RDA for iron. Vitamin C helps increase the absorption of iron from food.
Consuming a good source of vitamin C with plant-based sources of iron, such as whole grains and beans, can help women improve their iron status and prevent anemia.
2. Thiamine (Vitamin B1)
- Recommended Amount: The RDA for adult women is 1.1 mg/day. The recommendation increases during pregnancy (1.4 mg).
- Function: Thiamine helps the body process food into energy.
- Deficiency: Thiamine was first identified in 1912 when Polish biochemist Casimir Funk discovered that vitamin deficiency was the root cause of the disease beriberi.
Dr. Funk observed that chickens given white rice developed beriberi, while chickens given brown rice did not. When whole grains are milled into refined grains, thiamine is removed.
The chickens that ate only white rice developed a thiamine deficiency. Beriberi is classified as either wet or dry. Wet beriberi affects the cardiovascular system and ultimately results in heart failure.
Dry beriberi is characterized by decreased muscle strength and general malaise and can lead to paralysis.
Thiamine is now fortified into many refined grain products to help reduce the incidence of beriberi. Because of fortification, severe thiamine deficiency is not common in developed countries.
However, alcohol impairs the absorption of thiamine from food. Wernicke-Korsakoff syndrome is a thiamine deficiency associated with chronic alcohol abuse. (11)
- Toxicity: No toxicity disease has been observed with high thiamine intake.
- Food Sources: Thiamine is high in a variety of foods, including whole and fortified grains, pork, eggs, nuts, seeds, and legumes.
3. Riboflavin (Vitamin B2)
- Recommended Amount: The RDA for adult women is 1.1 mg/day. Recommendations are increased during pregnancy (1.4 mg) and lactation (1.6 mg).
- Functions: The major function of riboflavin is to help the body process food into energy. It also participates in many other chemical reactions that promote skin, blood, digestive tract, and general health. (12)
- Deficiency: Riboflavin deficiency, called ariboflavinosis, is characterized by cracking at the corners of the mouth and on the lips. Severe deficiency can impair liver and nervous system functions.
Riboflavin deficiency is rare and is normally accompanied by a deficiency of other B vitamins. Groups that may be susceptible to riboflavin deficiency include older adults and alcoholics.
- Toxicity: Toxicity is rare; however, extreme doses have been associated with increased risk of kidney stones, sensitivity to light, burning sensations, and numbness.
- Food sources: Good food sources of riboflavin include dairy, eggs, meat, green vegetables, and fortified grains products.
- Importance for Women: Women taking birth control pills are at greater risk for deficiency because these medications prevent the absorption of riboflavin.
Riboflavin deficiency during pregnancy is associated with an increased risk of adverse pregnancy outcomes, such as preeclampsia. (13)
Women who are vegan or consume a few portions of meat and dairy products must choose other good food sources of riboflavin.
4. Niacin (Vitamin B3)
- Recommended Amount: The RDA for adult women is 14 mg/day.
- Functions: The major function of riboflavin is to help the body process food into energy. It is also involved in the chemical reaction that creates sex and stress hormones.
Niacin is used for the prevention and treatment of heart disease. However, researchers are calling into question the efficacy of these treatments.
A 2017 Cochrane review of 23 randomized controlled trials found that niacin supplementation did not decrease the total number of deaths from heart disease, stroke, or heart attack. (14)
The reviewers concluded that niacin is not an effective treatment for the prevention of cardiovascular disease events.
- Deficiency: Niacin deficiency, known as pellagra, is unlikely in developed countries. Populations with low-protein diets have been known to develop niacin deficiency.
Pellagra is characterized by the “4 Ds”: dermatitis, dementia, diarrhea, and death. (15)
- Toxicity: Niacin supplements >3000 mg per day have been known to cause nausea, vomiting, and the “niacin flush.”
Symptoms of the niacin flush include warm red skin (like a sunburn), tingling, itching, dizziness, and rapid heartbeat. Prolonged excessive niacin intake may lead to liver toxicity. (16)
- Food Sources: Niacin is high in meat, poultry, fish, whole and fortified grains, legumes, and nuts.
- Importance for Women: Niacin is classified as a category C drug for pregnancy. This means that animal studies suggest that niacin supplementation may be harmful to the fetus.
There has not been enough research in humans to demonstrate that niacin is safe to use during pregnancy. The risks of using niacin supplements during pregnancy outweigh the potential benefits.
Furthermore, maternal niacin supplementation has shown to increase the vitamin’s content in breastmilk. Excess niacin could have adverse side effects on breastfeeding infants.
5. Pantothenic Acid (Vitamin B5)
- Recommended Amount: The RDA for women 14 years and older is 5 mg/day. Recommendations increase for women who are pregnant (6 mg) and breastfeeding (7 mg).
- Function: Pantothenic acid helps produce energy from food. It is also important for the production of new blood cells.
- Deficiency: Pantothenic acid is present in a variety of foods; therefore, a deficiency is rare. However, symptoms of a pantothenic acid deficiency may include generalized malaise, feelings of fatigue, depression, and irritability.
- Toxicity: No toxicity disease has been observed with high pantothenic acid intake.
- Food Sources: Many foods contain pantothenic acid, including meat, whole and fortified grains, beans, nuts, and some vegetables.
6. Pyridoxine (Vitamin B6)
- Recommended Amount: The RDA is 1.3 mg/day for women 19–50 years old. Recommendations are increased for women who are older than 50 (1.5 mg), pregnant (1.9), and breastfeeding (2 mg).
- Functions: Vitamin B6 is used in over 100 chemical reactions in the body. It helps facilitate reactions involved in cell growth, protein metabolism, and production of hemoglobin for red blood cells and neurotransmitters that regulate behavior. (17)
- Deficiency: Symptoms of a vitamin B6 deficiency include microcytic anemia, skin and lip irritations, neuropathy, depression, and confusion.
A deficiency of this vitamin is rare but can be caused by malnutrition and alcoholism. Isoniazid medications inhibit vitamin B6 and are known to cause neuropathy. Individuals taking isoniazid may need a vitamin B6 supplement.
- Toxicity: Excess B6 from supplements >200 mg/day can cause peripheral neuropathy. Although in the short term these effects may be reversible, long-term toxicity may lead to permanent neuropathy.
- Food Sources: Sources of vitamin B6 include meat, poultry, and fish, whole and fortified grains, potatoes, and eggs.
- Importance for Women: Vitamin B6 helps produce prostaglandins (a type of fat that controls inflammation and relaxation) and the hormones serotonin and dopamine, which improve mood.
Due to these effects, there is some evidence that vitamin B6 decreases premenstrual syndrome (PMS) and relieves cramps.
One study compared the PMS symptoms of women during their menstrual cycle with and without vitamin B6 supplementation. The women were instructed to take 40 mg of vitamin B6 per day for 1 week before their menstrual cycle and continue for 2 cycles. (18)
The women who took vitamin B had significantly decreased PMS symptoms when compared to their baseline. (18)
However, women may have perceived that their symptoms improved because they were receiving treatment. Many studies showing the benefits of vitamin B6 for PMS do not control for this critical element.
A recent review of 14 studies on dietary supplements for PMS treatment found that vitamin B6 relieved premenstrual stress and anxiety when combined with magnesium. (19)
Vitamin B6 had no effect when taken alone. Further research is needed to determine the true effect of vitamin B6 on PMS symptoms.
7. Biotin (Vitamin B7)
- Recommended Amount: The RDA for women over 19 years old is 30 mcg/day. Recommendations are increased for women who are breastfeeding (35 mcg).
- Function: Biotin helps the body process fat and protein. It also may help control blood sugar levels and maintain healthy skin, hair, and nails.
- Deficiency: Biotin deficiency is not common in the United States. Symptoms include hair loss, scaly skin, rashes, brittle nails, and fatigue.
- Toxicity: No toxicity disease has been observed with high biotin intake.
- Food Sources: Biotin is high in egg yolks, liver, nuts, avocados, and dairy.
- Importance for Women: Having adequate biotin is important for hair, skin, and nail health. In the absence of a deficiency, there is little evidence that biotin supplements will improve health.
However, biotin is often advertised in cosmetics to improve hair and nail thickness and strength or relieve dermatitis. Most people do not need a biotin supplement but can get adequate amounts from their diet.
8. Folate/Folic Acid (Vitamin B9)
- Recommended Amount: The RDA for women over 19 years old is 400 mcg dietary folate equivalents (DFE) per day. Recommendations are increased for women who are pregnant (600 mcg) and breastfeeding (500 mcg).
- Functions: Folate is important for cell division and growth. This makes folate vital during pregnancy so that the fetus can grow and develop properly. It is also used for the production of new red blood cells. (20)
- Deficiency: A folate deficiency can cause anemia. Symptoms of anemia include fatigue, weakness, irritability, paleness, decreased appetite, and shortness of breath.
Alcohol interferes with the absorption of folate and can lead to deficiency. Folate needs are increased during pregnancy. Deficiency causes neural tube defects known as spina bifida.
- Toxicity: No toxicity disease has been observed with high folate intake. However, since folate and vitamin B12 work together to make red blood cells, excess folate can mask a B12 deficiency.
This can be dangerous because an undetected B12 deficiency can lead to irreversible nerve damage.
- Food Sources: Supplements and fortified grain products contain the synthetic form of folate called folic acid. Folic acid is easier for the body to absorb than naturally occurring folate in foods.
Good food sources of folate include beans, dark leafy green vegetables, and citrus fruits.
- Importance for Women: Adequate folate levels are especially important for women of childbearing years. During the early stages of pregnancy, folate is involved in fetal neural development.
Early in pregnancy, the mother may not know that she is pregnant. If she is not eating adequate folate before and during the early stages of pregnancy, the child is at increased risk for spina bifida.
Spina bifida is a birth defect wherein the spinal cord does not form and close properly. This can cause varying levels of paralysis and compromised muscle control, depending on the severity.
9. Cobalamin (Vitamin B12)
- Recommended Amount: The RDA for women older than 14 years old is 2.4 mcg/day.
- Function: Vitamin B12 works with folate to synthesize DNA and form red blood cells. Additionally, it plays a role in proper nerve function. (21)
- Deficiency: A vitamin B12 deficiency causes anemia. Symptoms of anemia include fatigue, weakness, irritability, paleness, decreased appetite, and shortness of breath.
Severe B12 deficiency can lead to irreversible nerve damage. Early symptoms of neural damage include numbness, tingling, depression, and confusion. (22)
As vitamin B12 is mostly found in animal products, vegetarians and vegans are at high risk for deficiency. These individuals must take supplements or consume fortified foods.
Vitamin B12 is bound by proteins in food and must be released during digestion. Some individuals may have a decreased ability to release B12 from food and are at risk for deficiency.
These groups include older adults, individuals with gastrointestinal disorders, and those who underwent gastrointestinal surgery.
- Toxicity: No toxicity disease has been observed with high vitamin B12 intake.
- Food Sources: Vitamin B12 is found in animal products, including dairy, eggs, meat, fish, and poultry. Vegans can obtain B12 from supplements, fortified foods, and nutritional yeast.
Although more than half of Americans take vitamin or mineral supplements, the effects of supplements on overall health and disease are unclear. (23)
Some supplements can be dangerous for certain populations. Furthermore, supplements are not well regulated and may be contaminated with substances not indicated on the label.
If you do choose to take a supplement, these are some tips for ensuring safety:
- Multivitamins are usually better than single-nutrient supplements. There is little evidence that multivitamins increase the risk of death and disease. (24)
- Avoid supplements that contain >100% the daily value of any nutrient, particularly fat-soluble vitamins.
- Choose supplements that do not contain any “extra ingredients” that are not vitamins or minerals.
- Choose supplements that have a third-party certification seal. These inspections are optional for supplement companies and can signify to the consumer that the supplements are generally safe.
Most healthy people do not need to take dietary supplements. The best way to obtain all the essential vitamins is through a balanced and nutritious diet.
Whole foods contain many other nutrients that work synergistically with vitamins and minerals to promote optimal health.
However, there are some cases when supplementation is appropriate:
- Deficiency: If a vitamin deficiency disease is apparent, supplements should be used to correct the deficiency.
- Pregnant women: A prenatal vitamin is often recommended for women who are pregnant or planning a pregnancy.
Supplementation of folic acid and iron are usually recommended. Always consult your physician before taking supplements.
- Postmenopausal women: Many postmenopausal women are prescribed calcium and vitamin D to prevent or treat osteoporosis.
- Vegetarians/vegans: A well-planned vegetarian diet can include all the essential vitamins and minerals.
However, vegetarians and vegans may need supplements of vitamin B12, vitamin D, iron, zinc, and calcium. Always consult your physician before taking supplements.
A balanced, nutritious diet can supply all the essential vitamins. To meet their nutrient requirements, adults should choose whole grains and eat at least 5 cups of fruits and vegetables and at least 3 servings of dairy products per day.
Some women may need supplementation; however, this is not the norm. Always choose food first.