FNDH 400 Exam 4 Questions with Verified Solutions Latest Update 2025/2026

FNDH 400 Exam 4 Questions with Verified Solutions Latest Update 2025/2026 Difference between folic acid and folate - Answers Folate is a B Vitamin that exists in either reduced form (Folate) or its oxidized form (Folic acid). Folic acid refers to the synthetic form while folate refers to the natural form. Folate also has more than one glutamate in the tail (polyglutamate), while folic acid has one glutamate in the tail, (monoglutamate). Folic acid is more stable, folate can be destroyed by heat, oxidation, and light. Folic acid is better absorbed because of higher bioavailability. Dietary Folate Equivalents - Answers Folate's bioavailability is much lower than folic acid, to account for this difference, the DRI committee created dietary folate equivalents. 1 DFE = 1 ug food folate = 0.6 ug food folic acid = 0.5 ug folic acid on an empty stomach DFE = ug food folate + (ug folic acid x 1.7) The 1.7 came from research suggesting that folic acid from food was 85% bioavailable, compared to 50% for folate (85 divided by 50 equals 1.7) Cofactor form of Folate - Answers Tetrahydrofolate (THF) Why the US fortifies foods with folic acid - Answers The neural tube closes quickly after conception (21-28 days) so females need to be consuming folic acid very early in their pregnancy to decrease the risk of neural tube defects. In addition, around 50% of pregnancies are unplanned, so many women might not know they are pregnant in the period that folic acid needs to be consumed. Women of reproductive age need to be consuming folic acid all the time to decrease the risk of neural tube defects. The US chose to fortify grains so that folic acid will be in the food supply rather than relying on all reproductive aged women to be consuming folic acid supplements. What is megaloblastic anemia and why do Folate and Vitamin B12 deficiencies lead to this condition? - Answers Megaloblastic anemia is the same type of anemia that occurs in folate deficiencies characterized by fewer enlarged immature red blood cells, but in Vitamin B12 deficiencies, this can occur because there is not enough Cobalamin to convert 5-methyl THF to THF (tetrahydrofolate). Thus THF is not available for normal DNA synthesis and the red blood cells do not divide correctly. Scientific name of B12 - Answers Cobalamin Why is Vitamin B12 deficiency an issue for vegans and why most reliable sources of B12 are animal-based foods - Answers Animals consume microorganisms in soil or bacteria that produce Vitamin B12. Fermented soy products are not a reliable source of B12. Spirulina contains a pseudo-vitamin B12 that is not bioavailable. Plants and animals do not synthesize B12. Understand pernicious anemia, atrophic gastritis, intrinsic factor, and vitamin B12 deficiency - Answers Pernicious anemia is a condition of inadequate intrinsic factor production that causes poor vitamin B12 absorption, this is common in people over the age of 50 because they have the condition atrophic gastritis. Atrophic gastritis is a chronic inflammatory condition that leads to the loss of glands in the stomach, the loss of glands leads to decreased intrinsic factor production. Chronic inflammation of the mucous membrane in the stomach causes loss of gland production responsible for intrinsic factor secretion in the stomach. Intrinsic factor binds to the B12 in the duodenum and carries it to the ileum for absorption. It helps the B12 be endocytosed into the enterocyte by binding with the intrinsic factor receptor cubulin. Understand how folate/folic acid can mask a vitamin B12 deficiency and why it could be problematic - Answers If high levels of folate or folic acid is given during a vitamin B12 deficiency, it can correct this anemia. This is referred to as masking because it does not rectify the deficiency but it "cures" this symptom. This is problematic because it does not correct the more serious neurological problems that can result from Vitamin B12 deficiency. How intake of folate and Vitamin B12 can decrease homocysteine levels and whether this is a good way to decrease cardiovascular disease risk - Answers In order for THF (tetrahydrofolate) to be formed, a methyl group is transferred to cobalamin (vitamin B12) from 5-methyl THF (THF plus a methyl group), forming methyl-cobalamin. -Folate, vitamin B6, and vitamin B12: help convert homocysteine to methionine by providing methyl groups, thereby decreasing homocysteine levels. It was hypothesized that intake of these B vitamins may decrease CVD. -Research has found that these vitamins do decrease circulating homocysteine levels, but some have found that it does not decrease CVD risk. Some think it is because the studies have not focused on individuals with elevated homocysteine levels, while others believe that homocysteine is a biomarker or indicator of CVD, not a contributing factor to CVD development. Why Vitamin D is conditionally essential - Answers Vitamin D is unique because it is part vitamin hormone. Being considered part hormone for 2 reasons: 1 - we have the ability to synthesize it 2 - it has hormone-like functions Although the amount which is synthesized is often not enough to meet our needs thus we need to consume Vitamin D under certain circumstances. How Vitamin D is synthesized, activated and transported including the circulating form and the active form of the vitamin - Answers We synthesize Vitamin D3 from cholesterol. In the skin, cholesterol is converted to 7-dehydrocholesterol. In the presence of UV-B light, 7-dehydrocholesterol is converted to Vitamin D3. Synthesized with Vitamin D will combine with Vitamin D-binding protein (DBP) to be transported to the liver. Dietary D2 and D3 is transported to the liver via chylomicrons and then taken up in CM remnants. Once in the liver, the enzyme 25-hydroxylase (25-OHase) adds a hydroxyl group at the 25th carbon, forming 25-hydroxy vitamin D (25(OH)D, Calcidiol). This is the circulating form of Vitamin D. The active form of Vitamin D is formed with the addition of another hydroxyl group by the enzyme 1alpha-hydroxylase in the kidney forming 1, 25 hydroxy Vitamin D (1,25(OH)2D). Differences between D2 and D3 including structural, sources, and effectiveness - Answers D2 is primarily found in plants and yeast, it also contains an extra double bond in its tail. D3 is mainly made by animals. Vitamin D2 and D3 were once thought to be equivalent forms of Vitamin D, but research has found that D3 supplementation increases 25(OH)D concentrations more than D2 supplementation. How environmental factors affect Vitamin D synthesis - Answers Latitude: with increase distance from the equator there is a decrease in UV light exposure and vitamin D3 synthesis. Seasons: The difference in angle of the sun relative to latitude determines how many UV-B photons are absorbed before they reach the earth's surface. In some locations during some seasons the angle of the sun is so much that they do not synthesize vitamin D3. Time: Vitamin D3 synthesis increases in the morning before peaking at noon, then declines the rest of the day