Are You Missing Important Nutrients?

5 Nutrients Sometimes Missing in Low-Carb Diets

When we change our diets, we may wonder whether we're getting adequate nutrition.  Indeed, we should wonder about this in any case - it turns out that most people don't consistently get the full complement of the recommended daily intake of essential nutrients each day.  When we restrict our diets in various ways, it stands to reason that we may miss out on some of these nutrients if we're not careful.  In particular, diets which cause weight loss are more apt to be deficient in one or more nutrients.

Here are five nutrients which are most apt to drop when people limit carbohydrates in their diets, and three more that many people don't get enough of in general.  

There's information on how I chose these nutrients at the end of this article, as well as some technical details, caveats, and why it's better to get these nutrients from food and not pills

1
Thiamin

Macadamia Nuts
Macadamia Nuts. Alasdair Thompson/E+/Getty Images

Also called vitamin B1 (and is also spelled thiamine), thiamin is important in the body's energy production and brain and nervous system function. It works in concert with other B vitamins so that a depletion of one can cause others to function less well. It's also very prone to destruction in food processing, storage, and cooking. which is one of the reasons why flour and cereals are often enriched with thiamin. Adults should aim for about 1.1 mg (women) or 1.2 mg (men) of thiamin daily.

Low-Carb Sources of Thiamin

Pork - 4 oz. (before cooking) - almost 1 mg thiamin

Macadamia Nuts - 1 oz. - .34 mg thiamin, 1.5 grams net carb

Chicken Livers - 3.5 oz. - .31 mg thiamin, 1 gram carb

Pecans - 1 oz. - .19 mg thiamin - 1 gram net carb

Peanuts - 1 oz. - .18 mg thiamin - 2 grams net carb

Flaxseed - 1 Tablespoon - .17 mg thiamin, almost zero net carb

Asparagus - 6 medium spears - .14 mg thiamin, 2 grams net carb

Nutritional Yeast or Brewer's Yeast are both great sources, but read labels and look for sugar-free.  Also some are fortified with B-vitamins - for those a teaspoon of nutritional yeast will often give you what you need.  For unfortified, 2 tablespoons of nutritional yeast has about .6 mg of thiamin - brewer's yeast somewhat less.

Also: other nuts and nut butters, legumes, and tuna.  Many non-starchy vegetables have about .06 - .09 mg thiamin per cup.

2
Folate

Gokhan Okur

Folate, also known as vitamin B9, is the form of the nutrient found in whole foods.  Folic acid is the type found in supplements and fortified foods.  Folic acid is actually more bioavailable to be used by the body, so the recommended amounts are a little complicated, but basically the recommended daily allowance is 400 mcg. (also called DFE) for adults.

Folate is possibly best known for preventing a type of birth defect called a neural tube defect. It is used in many chemical reactions in the body, and its functions include cell formation (especially red blood cells).

Low-Carb Sources of Folate

Basically liver and anything green will give you lots of folate.

Chicken Livers - 3.5 oz. - 578 mcg folate - 1 gram carbohydrate

Asparagus - 6 spears - 134 mcg folate

Spinach - 1/2 cup cooked - 131 mcg folate

Brussels sprouts, 1/2 cup cooked - 78 mcg folate

Avocado - 1/2 cup sliced - 59 mcg folate

Romaine Lettuce - 1 cup - 64 mcg - half a gram net carb

Broccoli - 1/2 cup chopped - 52 mcg folate

Also: salmon, crab, lamb, and most green vegetables

3
Vitamin C

GeoStock/Getty Images

Probably the most well-known vitamin, vitamin C performs many functions in our bodies, from helping to make neurotransmitters in our brains to protecting our cells from damage, to building connective tissue. Vitamin C is easily degraded during storage and cooking. Keep your produce cool, and don't overcook it. Aim for at least 90 mg daily for adult males, 75 mg for females.

Low-Carb Sources of Vitamin C

Red Bell Pepper, 1/2 cup raw - 95 mg vitamin C, 3 grams net carb

Green Bell Pepper, 1/2 cup raw - 60 mg vitamin C, 

Brussels sprouts, 1/2 cup cooked - 48 mg vitamin C, 3 grams net carb

Broccoli, 1/2 cup cooked - 51 mg vitamin C, 3 grams net carb

Strawberries, 1/2 cup sliced - 49 mg vitamin C, 4 grams net carb

Cauliflower, 1/2 cup cooked - 44 mg vitamin C, 2 grams net carb

Grapefruit, 1/2 medium - 44 mg vitamin C, 9 grams net carb

Cabbage, 1 cup, raw, chopped - 33 mg vitamin C, 3 grams net carb

Also: kale and other greens, raspberries, green beans, cantaloupe. Almost all fruits and vegetables have some vitamin C.

4
Magnesium

Pumpkin Seeds. Arturo Delfin

Magnesium is a mineral that a lot of people do not eat enough of - some estimate that 30-50% of Americans don't reach the 400 mg recommended by the FDA. Unfortunately, people on low-carb diets may fare even worse - in one study, 70% of those 8 weeks into the Atkins diet were not eating sufficient magnesium. Worse, people who respond to low-carb diets may need magnesium even more than others, since it is important in glucose metabolism and blood sugar control. Other functions of magnesium include participating in protein synthesis, bone development and maintenance, DNA synthesis, and cell function.

Low-Carb Sources of Magnesium

Pumpkin Seeds - 1 oz kernels, roasted - 156 mg magnesium, 2 gm net carb 

Spinach (also chard), 1/2 cup cooked - 78 mg magnesium, 2 gm net carb

Soybeans (try black soybeans), 1/2 cup cooked - 74 mg magnesium, 3 gm net carb

Almonds, 1 oz - 77 mg magnesium, 3 gm net carb

Peanuts, 1 oz - 52 mg magnesium, 4 gm net carb

Flax seed, 1 tablespoon - 40 mg magnesium, scant carb

Also: legumes, fish, green vegetables, yogurt

5
Iron

Chicken Liver Pate. Rocketroom/Getty Images

Iron is extremely important to our health, for, without it, our cells cannot get oxygen. And yet, especially for women of childbearing age, it's a fairly common mineral deficiency, and people on low-carb diets tend to eat less of it. Women of childbearing age need to get 18 mg per day in their diets, while others only need about 8 mg.

Low-Carb Sources of Iron

Chicken Liver, 3 oz - 11 mg iron

Beef Liver, 3 oz - 5.2 mg iron

Soybeans, cooked, 1/2 cup 4.4 mg iron, 3 gm net carb

Spinach, cooked, 1/2 cup - 3.2 mg iron, 2 gm net carb

Roast Beef, 3 oz 3.1 mg iron

Asparagus, 6 spears - 2 mg iron, 2 gm net carb

Other Important Nutrients

These nutrients aren't specific to low-carb diets, but significant percentages of people do not get enough of these in their diets:

6
Vitamin D

Heather Winters/Getty Images

 Lower-than-optimal blood levels of vitamin D is becoming more common. It is thought this may be due to the fact that people are spending less time outside (especially in winter and in areas far from the equator) and wearing more sunscreen. It is fairly difficult to get enough in the diet. Very important for our bones, but is turning up as a factor in many aspects of health. Low-carb sources include salmon, tuna, eggs, yogurt, and liver.

7
Vitamin E

Dennis Flaherty/Getty Images

 Up to 80% of people may not be eating the recommended intake of vitamin E.  There are actually eight different forms, which is one of the reasons it's best to get vitamin E from foods, as supplements usually only contain one or two. Low-carb sources include most nuts and seeds (sunflower seeds are especially rich in vitamin E), greens, avocado, peppers, and shrimp.

8
Calcium

J Shepherd/Getty Images

Our bodies use calcium in so many ways, it's hard to list them all. Of course, we know  about bone health. It's also vital to the functioning of our muscles and nerves, and maintaining the correct acid/base balance. Low-carb sources include dairy products, sardines, canned salmon, tofu, and (as in almost everything) greens.

9
Notes, Technical Details, and Caveats

Vitamin Pills Vs Food: It's very tempting when reading a list like this to think, "I'll just take a vitamin pill." I don't think this is a good conclusion to leap to. Why? Because we are finding out there are many many nutrients in foods that we either didn't know about before, or that work together with the vitamins we know about. For example, scientists have now discovered tens of thousands of phytonutrients in the plant foods we eat, and we don't begin to understand the complexities of how they all interact and work together. There's evidence that there could be a similar situation with animal foods, although there isn't as much science in that area. 

Deficiencies vs Dietary Intake: I'm aware that there is a difference between having a diagnosed condition from a nutrient deficiency (e.g. rickets) vs having a low blood level of a nutrient vs not getting the recommended amounts in your diet. This article is strictly talking about the latter.

How I Drew up This List: The general "inadequate intake data" is from various scientific sources, including a study which looked at the intake of certain nutrients people were consuming before and during weight-loss diets (the A-Z Diet Study). I found their "baseline data" (before the diets started) to be illuminating, as, for example, most people were not eating enough vitamin E even before embarking on a weight-loss diet. Also, I drew on my own experience in designing low-carb menus which cover all the daily nutrient needs.

Less-Studied Nutrients: There are micronutrients which have been getting study and attention more recently that there isn't a lot of data for, with respect to how prevalent inadequate intake is. These include vitamin K2 and choline. This doesn't mean they aren't important, just that I don't know how much of a problem they are. (Educated guess is that low-carb diets would not tend impact those two particular nutrients adversely in most people, as some of the main sources are animal foods, e.g. egg yolks for choline.) Also, we have less information about the phytonutrients.

Vegetarians: Naturally, the whole picture shifts for vegetarian and vegan low-carbers, who are limiting their diets even more. In addition to the above, watch intake of vitamin B12, choline,  niacin, vitamin A, and zinc.

Low-Carb Tips for Vegetarians

Sources:

Gardner, CD, et. al. "Micronutrient quality of weight-loss diets that focus on macronutrients:results from the A TO Z study".  American Journal of Clinical Nutriion 2010 Aug;92(2):304-12.

National Institutes for Health, Office of Dietary Supplements, Fact Sheets (Calcium, Folate, Thiamin, Omega-3 Fats, Magnesium, Vitamin E, Vitamin C, and Vitamin D)

USDA National Nutrient Database for Standard Reference, Release 26.

Continue Reading