Health (things to know)

The Truth About Vitamins

Now that I’m officially a medical student, I’m gaining health and science knowledge at an alarming rate. It’s truly overwhelming (I’m talkin’ 16 hours a day right now), but I’m loving it.

It’s amazing to learn so much new information that is simultaneously so relevant. Much of the body’s ability to function properly really does come back to nutrition- it’s quite fundamentally how we live.

Last week I read a bit about vitamins. To be honest, vitamins always seemed like these mysterious things that I knew were “good for me” and “healthy,” but never really understood the mechanisms. People always talk about the super foods- like spinach and chia seeds- full of vitamin C, vitamin K, calcium, etc. But why do we need these things and what makes them so good for us?

Our cells function primarily through enzymes. Enzymes are tiny proteins that help speed up our metabolic reactions. Deficiencies in certain enzymes can lead to serious, potentially fatal problems. Enzymes are critical to ensuring that our body self regulates- for example, ability to generate energy, promote brain activity, and heal…to name a few.

Most enzymes don’t work by themselves. They need some kind of cofactor (or coenzyme) to bind to them . The binding will cause a chemical change in the enzyme to activate it. This is where vitamins come in.

Many vitamins serve as precursors to these “cofactors.” Without them, the cofactor cannot be made and thus the enzyme cannot function. Interestingly, there are several “essential” vitamins that the body needs to have that, over time, we stopped producing ourselves. For evolutionary reasons, our resources were better served ingesting these vitamins rather than synthesizing them.

Here’s one example: vitamin C is a precursor to a cofactor for collagen production (a component of connective tissue). Lack of vitamin C can eventually lead to bleeding in the gums because the body has no way of continually synthesizing the collagen it needs.

And another example: back in April, I told my doctor that I’d been feeling unusually lethargic- I worried that this might have something to do with the lack of red meat in my diet. After running a bunch of blood work, I found out this was due to low vitamin B-12.

Vitamin B12 is used for red blood cell formation, neurological function, and DNA synthesis. Deficiency is characterized by symptoms including fatigue, weakness, loss of appetite, and weight loss. Moral of the story: I wasn’t getting enough of an essential vitamin and it was making me SO tired. This is a great example of listening to your body; usually if you’re missing something, you’ll feel it in one way or another.

A great source of vitamins and minerals!

So now you know; your body needs vitamins. They play an important role in the life of your cells and your body as a whole. They have verified biochemical roles and there are plenty of ways to get them!

Here is a chart from WebMD with a comprehensive overview of essential vitamins and minerals.

Vitamin or Mineral
Examples of Good Food Sources
What It
Recommended Daily Amount
(RDA) or Adequate
Upper Limit
(The Highest Amount You Can Take Without Risk
Milk, yogurt, hard cheeses, fortified cereals, spinach
Essential for bone growth and strength, blood clotting, muscle contraction, and the transmission of nerve signals
Adults age 19-50: 1,000 milligrams/day
Adults age 51 and up: 1,200 milligrams/day
2,500 milligrams/day
Choline (Vitamin B complex)
Milk, liver, eggs, peanuts
Plays a key role in the production of cells and neurotransmitters
Men: 550 milligrams/day
Women: 425 milligrams/day
Pregnantwomen: 450 milligrams/day
Breastfeedingwomen: 550 milligrams/day
3,500 milligrams/day
Meats, poultry, fish, some cereals
Helps controlblood sugar levels
Adult men age 19-50: 35 micrograms/day
Adult men age 51 and up: 30 micrograms/day
Adult women age 19-50: 25 micrograms/day
Adult women age 51 and up:20 micrograms/day
Pregnant women: 30 micrograms/day
Breastfeeding women: 45 micrograms/day
Seafood, nuts, seeds, wheat bran cereals, whole grains
Important in themetabolism of iron
Adults: 900 micrograms/dayPregnant women: 1,000 micrograms/dayBreastfeeding women: 1,300 micrograms/day
10,000 micrograms/day
Bran cereal, peas, lentils, black beans, fruits, vegetables
Helps with digestion and the maintenance of blood sugar levels; reduces the risk of heartdisease
Adult men age 19-50: 38 grams/dayAdult men age 51 and up: 30 grams/dayAdult women age 19-50: 25 grams/dayAdult women age 51 and up:21 grams/dayPregnant women: 28 grams/dayBreastfeeding women: 29 grams/day
Fluoridated water, some sea fish, sometoothpastesand mouth rinses
Prevents the formation oftoothcavities and stimulates the growth of bone
Adult men: 4 milligrams/dayAdult women (including pregnant and breastfeeding):3 milligrams/day
10 milligrams/day
Folic Acid (Folate)
Dark, leafy vegetables; enriched and whole grain breads; fortified cereals
Key for the development of cells, protein metabolism andheart health; in pregnant women, helps prevent birth defects
Adults: 400 micrograms/dayPregnant women: 600 micrograms/dayBreastfeeding women: 500 micrograms/day
1,000 micrograms/day
Processed foods and iodized salt
Important in the production ofthyroid hormones
Adults: 150 micrograms/day Pregnant women: 220 micrograms/day Breastfeeding women: 290 micrograms/day
1,100 micrograms/day
Fortified cereals, beans, lentils, beef, eggs
Key component of red blood cells and many enzymes
Men: 8 milligrams/dayWomen age 19-50: 18 milligrams/dayWomen age 51 and up: 8 milligrams/dayPregnant women: 27 milligrams/day Breastfeeding women: 9 milligrams/day
45 milligrams/day
Green leafy vegetables, Brazil nuts, almonds, soybeans, halibut, quinoa
Helps with heart rhythm, muscle and nerve function, bone strength
Adult men age 19-30: 400 milligrams/dayAdult men age 31 and up: 420 milligrams/dayAdult women age 19-30: 310 milligrams/day Adult women age 31 and up: 320 milligrams/dayPregnant women: 350-360 milligrams/dayBreastfeeding women: 310-320 milligrams/day

For magnesium in food and water, there is no upper limit.

For magnesium in supplementsor fortified foods: 350 milligrams/day

Nuts, beans and other legumes, tea, whole grains
Important in forming bones and some enzymes
Men: 2.3 milligrams/day Adult women: 1.8 milligrams/day Pregnant women: 2.0 milligrams/day Breastfeeding women: 2.6 milligrams/day
11 milligrams/day
Legumes, grains, nuts
Key in the production of some enzymes
Adults: 45 micrograms/dayPregnant and breastfeeding women: 50 micrograms/day
2,000 micrograms/day
Milk and other dairy products, peas, meat, eggs, some cereals and breads
Allows cells to function normally; helps the body produce energy; key in bone growth
Adults: 700 milligrams/day
Adults up to age 70: 4,000 milligrams/dayAdults over age 70: 3,000 milligrams/dayPregnant women: 3500 milligrams/dayBreastfeeding women: 4,000 milligrams/day
Sweet potato, bananas, yogurt, yellowfin tuna, soybeans
Important in maintaining normal fluid balance; helps control blood pressure; reduces risk of kidney stones
Adults: 4,700 milligrams per dayBreastfeeding women: 5,100 milligrams/day
Organ meats, seafood, some plants (if grown in soil with selenium) Brazil nuts.
Protects cells from damage; regulates thyroid hormone
Adults: 55 micrograms/dayPregnant women: 60 micrograms/dayBreastfeeding women: 70 micrograms/day
400 micrograms/day
Foods to which sodium chloride (salt) has been added, like salted meats, nuts, butter, and a vast number of processed foods
Important for fluid balance
Adults age 19-50: 1500 milligrams/dayAdults age 51-70: 1,300 milligrams/dayAdults age 71 and up: 1,200 milligrams/day
2,300 milligrams/day
Vitamin A
Sweet potato with peel, carrots, spinach, fortified cereals
Necessary for normal vision, immune function, reproduction
Men: 900 micrograms/dayWomen: 700 micrograms/day
3,000 micrograms/day
Vitamin B1(Thiamin)
Whole grain, enriched, fortified products; bread; cereals
Allows the body to process carbohydrates and some protein.
Men: 1.2 milligrams/dayWomen: 1.1 milligrams/dayPregnant and breastfeeding women: 1.4 milligrams/day
Vitamin B2(Riboflavin)
Milk, bread products, fortified cereals
Key in metabolism and the conversion of food into energy; helps produce red blood cells
Men: 1.3 milligrams/day Women: 1.1 milligrams/day Pregnant Women: 1.4 milligrams/day Breastfeeding Women: 1.6 milligrams/day
Vitamin B3(Niacin)
Meat, fish, poultry, enriched and whole grain breads, fortified cereals
Assists in digestion and the conversion of food into energy; important in the production of cholesterol
Men: 16 milligrams/dayWomen: 14 milligrams/dayPregnant Women: 18 milligrams/day ?Breastfeeding women: 17 milligrams/day

For niacin in natural sources, there is no upper limit.

For niacin in supplements or fortified foods: 35 milligrams/day

Vitamin B5(Pantothenic Acid)
Chicken, beef, potatoes, oats, cereals, tomatoes
Important in fatty acid metabolism
Adults: 5 milligrams/dayPregnant women: 6 milligrams/dayBreastfeeding women: 7 milligrams/day
Vitamin B6
Fortified cereals, fortified soy products, organ meats
Important for the nervous system; helps the body metabolize proteins and sugar
Men age 19-50:1.3 milligrams/dayMen age 51 up: 1.7 milligrams/dayWomen age 19-50: 1.3 milligrams/dayWomen age 51 up: 1.5 milligrams/dayPregnant women: 1.9 milligrams/dayBreastfeeding women: 2 milligrams/day
100 milligrams/day
Vitamin B7(Biotin)
Liver, fruits, meats
Helps with the synthesis of fats, glycogen and amino acids
Adults: 30 micrograms/dayBreastfeeding women: 35 micrograms/day
Vitamin B12(Cobalamin)
Fish, poultry, meat, fortified cereals
Important in the production of red blood cells
Adults: 2.4 micrograms/dayPregnant women: 2.6 micrograms/dayBreastfeeding women: 2.8 micrograms/day
Vitamin C
Red and green peppers, kiwis, oranges, strawberries, broccoli
Antioxidant that protects against cell damage, boosts the immune system, forms collagen in the body
Men: 90 milligrams/dayWomen: 75 milligrams/dayPregnant women: 85 milligrams/dayBreastfeeding women: 120 milligrams/day
2,000 milligrams/day
Vitamin D (Calciferol)
Fish liver oils, fatty fish, fortified milk products, fortified cereals; also, formed naturally as a result of sunlight exposure
Crucial in metabolizing calcium for healthy bones
Adults age 18-50: 5 micrograms/dayAdults age 51-70: 10 micrograms/dayAdults over age 70: 15 micrograms/dayPregnant and breastfeeding women: 5 micrograms/day
50 micrograms/day
Vitamin E (alpha-tocopherol)
Fortified cereals, sunflower seeds, almonds, peanut butter, vegetable oils
Antioxidant that protects cells against damage
Adults (including pregnant women): 15 milligrams/dayBreastfeeding women: 19
1,000 milligrams/day
Vitamin K
Green vegetables like spinach, collards, and broccoli; brussels sprouts; cabbage
Important in blood clotting and bone health
Men: 120 micrograms/day


Women (including pregnant and breastfeeding):90 micrograms/day

Red meats, some seafood, fortified cereals
Supports the body’s immunity and nerve function; important in reproduction
Men: 11 milligrams/day


Women: 8 milligrams/dayPregnant women: 11 milligrams/dayBreastfeeding women: 12 milligrams/day

40 milligrams/day

2 thoughts on “The Truth About Vitamins

    • I always wondered too 🙂
      I’m not 100% sure, but I think vitamin pills are digested in a different way than normal vitamins in food… so you need a higher dose in pill form than you would in food. But I’d have to look into this more to really know- I just remember reading it somewhere way back when.
      But vitamin B12 pills have definitely helped me a lot!!

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