What Is Folate?
There are two forms of the vitamin folate: the naturally occurring folate in foods and the synthetic form, folic acid, which is added to foods (such as ready-to-eat cereals and grains) and found in supplements. (A very small amount of folic acid can occur naturally in foods. But, for practical purposes in this book, folic acid always refers to the synthetic variety.)
Functions of Folate
Folate Is Vital for DNA Synthesis
Folate is vital to making the DNA in your cells. If the synthesis of DNA is disrupted, your body’s ability to create and maintain new cells is impaired. For this reason, folate plays many important roles, from maintaining healthy blood cells and preventing birth defects to possibly fighting cancer and heart disease. Folate also helps your body use amino acids and is needed to help red blood cells divide and increase in adequate numbers.
Folate Prevents Birth Defects
Folate plays an extremely important role during pregnancy, particularly in the first few weeks after conception, often before the mother knows she is pregnant. Folate is needed to create new cells so that the baby can grow and develop. A deficiency during pregnancy can result in birth defects called neural tube defects. The neural tube forms the baby’s spine, brain, and skull. If the neural tube doesn’t develop properly, two common birth defects, anencephaly and spina bifida, can occur. In anencephaly, the brain doesn’t completely form so the baby can’t move, hear, think, or function. An infant with anencephaly dies soon after birth. In spina bifida, the baby’s spinal cord and backbone aren’t properly developed, causing learning and physical disabilities, such as the inability to walk. Folic acid reduces the risk of these birth defects by 50 to 70 per cent if consumed at least the month prior to conception and during the early part of pregnancy.
Research studies to date suggest that synthetic folic acid has a stronger protective effect than the folate found naturally in foods.
Folate Reduces Some Cancer Risks
Inadequate amounts of folate in the body can disrupt the cell’s DNA, potentially triggering the development of cancer, and adequate intake of folate has been shown to help reduce the risk of certain cancers, specifically colon cancer. Studies show that men and women taking a multivitamin supplement or otherwise consuming the recommended amounts of folate have a lower risk of developing colon cancer.
Other studies show an association between diets low in folate and an increased risk of breast and pancreatic cancers.
Your body absorbs the synthetic folic acid more easily than it absorbs naturally occurring folate. In fact, synthetic folic acid is absorbed 1.7 times more efficiently than most folate that is found naturally in foods. Because of this, your folate needs are measured in dietary folate equivalents (DFE). Most adults should consume 400 micrograms DFE of folate daily. While the foods in your diet analysis program database list the micrograms of folate as DFE, the Nutrition Facts panel on the food label doesn’t make this distinction. To convert the micrograms of folic acid found on the food labels of foods with folic acid added, such as enriched pasta, rice, cereals, and bread, to dietary folate equivalents, multiply the amount listed on the label by 1.7: 100 μg x 1.7 = 170 μg DFE
Because 50 per cent of pregnancies in the United States are unplanned, women at risk of becoming pregnant should consume 400 micrograms of synthetic folic acid daily from fortified foods or supplements, along with a diet high in naturally occurring folate. Women with a family history of neural tube defects should, under the guidance of their physicians, take even larger amounts.
Since 1998, the FDA has mandated that folic acid is added to all enriched grains and cereal products. This enrichment program has reduced the incidence of neural tube defects by more than 25 per cent. Enriched pasta, rice, bread and cereals, legumes (dried peas and beans), leafy green vegetables (spinach, lettuce, collards), broccoli, asparagus, and orange juice are all good sources of this vitamin.
Too Much or Too Little
There isn’t any danger in consuming excessive amounts of naturally occurring folate in foods.
However, consuming too much folic acid, either through supplements or fortified foods, can be harmful to individuals who are deficient in vitamin B12. A vitamin B12 deficiency can cause anaemia and, more dangerous, crippling and irreversible nerve damage.
Too much folate in the diet masks the symptoms of B12- deficiency anaemia. Though the folate can correct anaemia, the nerve damage due to the vitamin B12 deficiency persists.
This delays a proper diagnosis and corrective therapy with vitamin B12. By the time the person is given the vitamin B12, irreversible nerve damage may have occurred. While, as you read, low folate intake may be associated with increased cancer risk, studies suggest that folate consumption double the DRI or even higher may increase the risk of cancer.
When it comes to folic acid, some is essential, but more may not be better.
A folate deficiency can also result in abnormally large and immature cells known as megaloblasts (megalo = large). These megaloblasts develop into abnormally large red blood cells, or macrocytes, that have a diminished oxygen-carrying capacity. Eventually, macrocytic anaemia causes a person to feel tired, weak, and irritable and to experience shortness of breath. Because folate acts with vitamin B12 to produce healthy red blood cells, a deficiency of either vitamin can lead to macrocytic anaemia.
An upper level of 1,000 micrograms has been set for folic acid from enriched and fortified foods and supplements to safeguard those who may be unknowingly deficient in vitamin B12.
Fulfil Your Folate Needs
Have a bowl of cereal in the morning.
Add chickpeas to your salad.
Enjoy a tossed salad with your lunch.
Add fresh spinach leaves to your sandwich.
Have a handful of crackers as a late afternoon snack.
What Is Vitamin B12?
The family of compounds referred to as vitamin B12 is also called cobalamin because it contains the metal cobalt. Vitamin B12 is the only water-soluble vitamin that can be stored in your body, primarily in your liver.
B12 Needs Intrinsic Factor to Be Absorbed
A protein produced in your stomach called intrinsic factor is needed to promote vitamin B12 absorption. Intrinsic factor binds with vitamin B12 in your small intestine, where the vitamin is absorbed.
Individuals who cannot produce intrinsic factor are unable to absorb vitamin B12 and are diagnosed with pernicious anaemia (pernicious = harmful). Individuals with this condition must be given regular shots of vitamin B12, which injects the vitamin directly into the blood, bypassing the intestine.
Because your body stores plenty of vitamin B12 in the liver, the symptoms of pernicious anaemia can take years to develop.
Functions of Vitamin B12
Vitamin B12 Is Vital for Healthy Nerves and Red Blood Cells
Your body needs vitamin B12 to use certain fatty acids and amino acids and to make the DNA in your cells. Vitamin B12 is also needed for healthy nerves and tissues.
Like folate, vitamin B12 plays an important role in keeping your cells, particularly your red blood cells, healthy.
It is also one of the three B vitamins that collectively could be heart healthy.
Adults need 2.4 micrograms of vitamin B12 daily. American adults, on average, consume more than 4 micrograms daily.
The body’s ability to absorb naturally occurring vitamin B12 from foods diminishes with age. This decline appears to be due to a reduction in the acidic juices in the stomach, which are needed to break the bonds that bind the B12 to the proteins in food. If the bonds aren’t broken, the vitamin can’t be released. Up to 30 per cent of individuals over the age of 50 experience this decline in acidic juices in their stomachs. Not surprisingly, the pernicious anaemia associated with a vitamin B12 deficiency occurs in about 2 per cent of individuals over the age of 60.66
With less acid juice present, the bacteria normally found in the intestines aren’t properly destroyed and so tend to overgrow. This abundance of bacteria feed on vitamin B12, diminishing the amount of the vitamin that may be available.
Luckily, the synthetic form of vitamin B12 that is used in fortified foods and supplements isn’t bound to a protein, so it doesn’t depend on your stomach secretions to be absorbed. (Synthetic vitamin B12 still needs intrinsic factor to be absorbed.)
Because the synthetic variety is a more reliable source, individuals over the age of 50 should meet their vitamin B12 needs primarily from fortified foods or a supplement.
Naturally occurring vitamin B12 is found only in foods from animal sources, such as meat, fish, poultry, and dairy products.
A varied diet that includes the minimum recommended servings of these food groups will easily meet your daily needs. Synthetic vitamin B12 is found in fortified soy milk and some ready-to-eat cereals, which are ideal sources for older adults and strict vegetarians, who avoid all foods from animal sources.
If you are relying solely on fortified foods to meet your vitamin B12 needs, continually check the labels on these products to make sure they haven’t unexpectedly been reformulated to exclude the vitamin.
Too Much or Too Little
At present, there are no known risks of consuming too much vitamin B12 from foods, fortified foods, or supplements, and no upper level has been set.
There is also no known benefit from taking B12 supplements if your diet contains foods from animal sources and/or fortified foods.
A Vitamin B12 Deficiency Can Cause Macrocytic Anemia
Because vitamin B12 and folate work closely together to make healthy red blood cells, a vitamin B12 deficiency can cause macrocytic anaemia, the same type of anaemia caused by a folate deficiency. In macrocytic anaemia due to a vitamin B12 deficiency, there is enough folate available for red blood cells to divide, but the folate can’t be utilized properly because there isn’t enough vitamin B12 available. In fact, the true cause of macrocytic anaemia is more likely a B12 deficiency than a folate deficiency.
Because pernicious anaemia (caused by a lack of intrinsic factor) is a type of macrocytic anaemia, its initial symptoms are the same as those seen in folate deficiency: fatigue and shortness of breath.
Vitamin B12 is needed to protect nerve cells, including those in your brain and spine, so one long-term consequence of pernicious anemia is nerve damage marked by tingling and numbness in the arms and legs and problems walking. If diagnosed early enough, these symptoms can be reversed with treatments of vitamin B12.
Table Tips Boost Your B12
Enjoy heart-healthy fish at least twice a week.
Sprinkle your steamed vegetables with reduced-fat shredded cheese.
Drink milk or fortified soy milk.
Try a cottage cheese and fruit snack in the afternoon.
Enjoy a grilled chicken breast on a bun for lunch.
You don’t have to go out of your way to ensure that your dog’s daily chow contains enough vitamin C. Dogs and many other animals possess an enzyme that can synthesize vitamin C from glucose.
Humans, however, lack the necessary enzyme for this conversion and have to rely on food to meet their daily vitamin C needs.
Functions of Vitamin C
Vitamin C Acts as a Coenzyme
Vitamin C, also known as ascorbic acid, acts as a coenzyme that is needed to synthesize and use certain amino acids. In particular, vitamin C is needed to make collagen, the most abundant protein in your body. Collagen is plentiful in your connective tissue, which supports and connects all your body parts, so this protein is needed for healthy bones, teeth, skin, and blood vessels. Thus, a vitamin-C–deficient diet would affect your entire body.
Vitamin C Acts as an Antioxidant
Like beta-carotene and vitamin E, vitamin C acts as an antioxidant that may help reduce the risk of chronic diseases.
White blood cells as heart disease and cancer. It also helps you absorb the iron in plant foods such as grains and cereals and break down histamine, the component behind the inflammation seen in many allergic reactions.
Vitamin C Boosts Your Immune System
Vitamin C helps keep your immune system healthy by enabling your body to make white blood cells, like the ones shown in the photo above. These blood cells fight infections, and this immune-boosting role has fostered the belief that high doses of vitamin C can cure a common cold. (The “Gesundheit!
Women need to consume 75 milligrams of vitamin C daily, and men need to consume 90 milligrams daily to meet their needs.
Smoking accelerates the breakdown and elimination of vitamin C from the body, so smokers need to consume an additional 35 milligrams of vitamin C every day to make up for these losses.
Americans meet about 90 per cent of their vitamin C needs by consuming fruits and vegetables, with orange and/or grapefruit juice being the most popular source in the diet. One serving of either juice will just about meet an adult’s daily needs.
Tomatoes, peppers, potatoes, broccoli, oranges, and cantaloupe are also excellent sources.
Too Much or Too Little
Brendan, the track athlete introduced at the beginning of this chapter, attempted to ward off a cold by taking vitamin C supplements. His attempt to solve one medical dilemma created another one that impeded his training more than his sniffling and sneezing.
Though excessive amounts of vitamin C aren’t known to be toxic, consuming more than 3,000 milligrams daily through the use of supplements has been shown to cause nausea, stomach cramps, and diarrhoea.
Brendan can attribute the diarrhoea he experienced to his daily 3,500-milligram supplement of vitamin
Once he stopped taking the supplement, his diarrhoea ceased.
The upper level for vitamin C for adults is set at 2,000 milligrams to avoid the intestinal discomfort that excessive amounts of the vitamin can cause. Too much vitamin C can also lead to the formation of kidney stones in individuals with a history of kidney disease. Because vitamin C helps to absorb the form of iron found in plant foods, those with a rare disorder called hemochromatosis (hemo = blood; chroma = color; osis = condition), which causes the body to store too much iron, should avoid excessive amounts of vitamin C.
Iron toxicity is extremely dangerous and can damage many organs in your body, including the liver and heart.
For centuries, scurvy, the disease of a vitamin C deficiency, was the affliction of sailors on long voyages. After many weeks at sea, sailors would run out of vitamin-C–rich produce and then develop the telltale signs of scurvy: swollen and bleeding gums, a rough rash on the skin, coiled or curly arm hairs, and wounds that wouldn’t heal. Because vitamin C is needed for healthy blood vessels, a deficiency also often causes purple colored spots, a sign of skin haemorrhages, to appear on the skin and in mucus membranes of the body such as the lining of the mouth.
In 1753, a British naval surgeon discovered that orange and lemon juice prevented scurvy. Decades later, the British government added lemon or lime juice to their standard rations for sailors to thwart scurvy. In 1919, vitamin C was discovered as the curative factor in these juices.
Juicy Ways to Get Vitamin C
Have a least one citrus fruit (such as an orange or grapefruit) daily.
Put sliced tomatoes on your sandwich.
Enjoy a fruit cup for dessert.
Drink low-sodium vegetable juice for an afternoon refresher.
Add strawberries to your low-fat frozen yoghurt.
Pantothenic Acid and Biotin
What Are Pantothenic Acid and Biotin?
Pantothenic acid and biotin are B vitamins.
Functions of Pantothenic
Acid and Biotin Pantothenic acid and biotin aid in the metabolism of the nutrients that provide you with energy: carbohydrates, proteins, and fats.
Adults need 5 milligrams of pantothenic acid and 30 micrograms of biotin daily.
Both pantothenic acid and biotin are widely available in foods, including whole grains and whole-grain cereals, nuts and legumes, broccoli, peanut butter, meat, milk, and eggs. Most Americans easily meet their needs.
Biotin deficiency is so rare that an accurate list of the amount in foods is hard to find. In addition to its abundance in foods, biotin can be synthesized by the bacteria in your intestinal tract, providing yet another avenue to meet your needs.
Eating a healthy diet to meet all of your other B vitamin needs will ensure that you meet your needs for pantothenic acid and biotin.
Too Much or Too Little
Like many of the other B vitamins, there are no known adverse effects from consuming too much pantothenic acid or biotin.
An upper level has not been determined for either of these vitamins.
Although a pantothenic acid deficiency is rare, if you do fall short of your needs, your symptoms might include fatigue, nausea, vomiting, numbness, muscle cramps, and difficulties walking.
During World War II, prisoners of war in Asia experienced a “burning feet” syndrome.
The symptoms ranged from heat sensations and tingling on the soles of their feet to a painful burning intense enough to disrupt sleep. Their diet consisted predominantly of nutrient-poor polished rice. A doctor in India who was studying an identical phenomenon in his patients discovered that when he gave them supplements of pantothenic acid, the condition stopped. In both cases, the syndrome was later attributed to a diet deficient in pantothenic acid.
Consuming inadequate amounts of biotin can cause hair loss, skin rash, and feelings of depression, fatigue, and nausea. Though deficiencies are rare, they can occur if you eat a lot of raw egg whites. The protein avidin, found in egg whites, binds with biotin and blocks it from being absorbed in your intestine.
Cooking the egg denatures and inactivates the protein, eliminating the problem.
1. Vitamins are essential nutrients needed by your body to grow, reproduce, and maintain good health. They are found naturally in foods, added to foods, or in pill form in dietary supplements.
2. Fat-soluble vitamins are stored in your body and require fat for absorption. They can accumulate to the point of toxicity if your intake is excessive. Water-soluble vitamins are absorbed with water and typically aren’t stored for extended periods. Excess amounts of water-soluble vitamins do not accumulate to toxic levels but can be harmful if you routinely consume too much.
3. Antioxidants, such as vitamins E and C, and beta carotene, suppress harmful oxygen-containing molecules called free radicals that can damage cells. Free radicals can contribute to chronic diseases such as cancer and heart disease and accelerate the ageing process. Diets abundant in antioxidant-rich fruits, vegetables, and whole grains are associated with a lower incidence of many diseases.
4. Vitamin A is needed for strong vision, reproduction, and healthy fetal development. Carotenoids are yellow-reddish pigments that give some fruits and vegetables their vibrant yellow-red color. The carotenoid beta-carotene is a common provitamin that can be converted to vitamin A in your body. Two other carotenoids, lutein and zeaxanthin, are being investigated for their potential role in eye health. The carotenoid lycopene acts as an antioxidant in the body.
5. Vitamin D is necessary for absorption of calcium and phosphorus. Although vitamin D can be made in your body with the help of ultraviolet rays from the sun, some individuals are not exposed to enough sunlight to meet their needs. A deficiency of vitamin D can cause rickets in children and osteomalacia in adults. Milk and fortified yoghurts are excellent sources of vitamin D.
6. Vitamin E is an antioxidant that protects your cells’ membranes. It plays an important role in helping prevent the “bad” LDL cholesterol carrier from being oxidized. High levels of artery-clogging, oxidized LDL cholesterol are a risk factor for heart disease. Vitamin K helps your blood to clot and to synthesize proteins that keep bones healthy.
7. The B vitamins thiamin, riboflavin, niacin, vitamin B6, pantothenic acid, and biotin are all coenzymes that assist in numerous energy-producing reactions.
8. The B vitamins folate and vitamin B12 are needed for healthy red blood cells. A deficiency of either can cause macrocytic anaemia. Adequate amounts of folic acid can reduce the risk of certain birth defects, including spina bifida and anencephaly. Prolonged vitamin B12 deficiency can cause nerve damage.
9. Vitamin C is needed for healthy bones, teeth, skin, and blood vessels, and for a healthy immune system. Excessive amounts can cause intestinal discomfort. Vitamin C doesn’t prevent the common cold, but may