Micronutrient Smackdown: The Best Time to Take Your Vitamins and Minerals

When I meet with people for nutrition coaching, I always ask about their medicine and supplement intake in addition to what they are eating. Why? Because I can quickly spot gaps in their diet and want to be sure they are filling those gaps with supplements. Especially if they don't plan on adding food sources of the missing nutrients in the near future. And, I want to be certain they are taking their supplements the right way because many people were never told by their physician (or the supplement bottle doesn’t mention this) how to take a particular mineral.

You see, like sorority girls, minerals are finicky. There are many forms for each one (calcium carbonate, calcium citrate, calcium phosphate for example) and some just don’t like each other (calcium interferes with iron absorption) or certain medications (calcium decreases the absorption of some antibiotics) and others have formed a team and help one another (magnesium and calcium for example). So, how do you know what to take when? Here’s a quick rundown of some of the common ones people need and how to take them:

Multivitamin – take with food and preferably food with a little fat (to enhance the absorption of fat soluble vitamins you need fat in your gut).

Calcium – take up to 600 mg at a time. If your physician told you to take 1,200 total mg/day, take them in two separate doses of 600 mg, spaced apart. Your body only absorbs up to 500-600 mg at a time.

Calcium carbonate – take with food to enhance absorption.
Calcium citrate can be taken at any time of the day.

Magnesium – no single pill multivitamin contains 100% of your magnesium needs per day (it is a very big mineral) and according to population based data, many people don’t consume enough magnesium through their food intake. Diuretics and antibiotics can contribute to magnesium depletion. Magnesium can decrease the absorption of tetracycline (an antibiotic); so take it at a different time of the day. Many antacids and laxatives contain magnesium –be careful consuming these due to the potential for elevated blood magnesium levels. Enteric coating of magnesium supplements can decrease their absorption.

Iron – there are two types of supplements.
Non-heme iron is the most popular (all over the counter kinds of iron unless it says it contains heme iron) and should be taken with vitamin C rich foods, a heme iron source (meat) and not taken close in proximity to calcium containing foods or supplements. In addition, it’s best not to take this with leafy greens or bread as each has compounds that decrease the absorption of non-heme iron.

Heme iron – easy, take anytime of the day. You don’t need to worry about what you take it with or without.

Zinc – taking an iron supplement with large quantities of iron may decrease zinc absorption. According to NIH, taking iron between meals will help (see note above about iron). High intakes of iron can impair absorption of copper.

Potassium – found in very minor amounts in multivitamins. Don’t take extra potassium unless your physician tells you to do so. Having too much or too little potassium can be very serious.

Given that so minerals are picky and like to be treated a certain way, you are probably wondering why you should even bother taking a multivitamin mineral supplement. However, I do believe in multis and take one myself and I supplement with minerals as needed. After all, I try to eat a wide variety of foods but, I realize that there are probably vitamins and minerals I am missing out on.

Top Vegetarian Sources of Iron

The best sources of iron are from meat, poultry and fish – all of which contain heme iron. Heme iron is absorbed better than the type of iron found in plants – non-heme iron. For vegetarians of course, this is a moot point since animal foods aren’t an option. Therefore, you’ll need to be extra aware of your iron intake.



The top vegetarian sources of iron include:
Fortified cereals (look for 100% DV for iron)
Instant oatmeal
Lentils
Lima, navy, lima, black, pinto
Molasses
Spinach
Black-eyed peas

Be sure to include several of these foods in your diet and consume them with vitamin C to enhance the absorption of non-heme iron. And, take your calcium supplements and antacids separately since they can inhibit the absorption of non-heme iron.

How Much Iron do You Get from Cooking in a Cast Iron Skillet?

For years I’ve heard that cooking in a cast iron skillet can increase the iron content of your food. And then I realized all the work involved in maintaining an iron skillet. Storing one would be cumbersome, I’d have to season it with some sort of grease (after all, if you aren’t using non-stick pans you have to make the stuff not stick somehow) and it could rust. That’s just a little to high maintenance for a skillet in my opinion. However, I still wondered about the iron content. Does it really make a dent in a person’s diet?

In an effort to find the truth about the iron content in cast iron cooking utensils, I turned to my partner in research, google scholar. Luckily, a typewritten and scanned thesis from 1984 appeared that examined this very topic! After reading through this study I came to a chart that outlined how much the iron content increased if a particular meal was cooked in an iron utensil versus a non-iron utensil.

A few items on this list were not a surprise to me. Stew, chili with meat, applesauce and spaghetti sauce (all of which contained some acidic ingredients) gained a significant amount of iron if cooked in an iron versus non-iron utensil (applesauce was the all time leader in iron gained). However, there were also many surprises to me: scrambled eggs, rice and a white sauce. In fact, eighteen of the twenty foods cooked in iron and non-iron skillets absorbed significantly more iron than when cooked in the non-iron skillet. This study found that foods with a higher moisture content, more acidity and a longer cooking time take up more iron from the iron cookware.

I have to thank Cheryl Eileen Nossaman’s work for finally answering that question I’ve always wondered about. I’m still not going to use iron cookware because I prefer using oil versus grease in my pans. But at least I now know that iron utensils can in fact add iron to one’s diet!