Many of us take vitamins and other nutritional supplements. In fact, researchers from Harvard analyzed data from nearly 125,000 middle-aged and older people and found that an astounding 88% of women and 81% of men took supplements.

Unfortunately, a lot of us take nutritional supplements wrong.

We don’t take high-enough doses…or we take them at the wrong time of day…or we combine them with other supplements, foods or drugs that can block absorption.

Good news: I’ve counseled thousands of patients on the best ways to take ­vitamins, and I can assure you that taking them correctly can be simple and straightforward.

What you might be doing wrong—and how to quickly fix the problem…

Vitamin mistake #1: You take a dose that’s too low. There are many ­nutrient-nutrient interactions that can reduce the absorption of individual ­nutrients by 5% to 10%. Example: Iron cuts the absorption of zinc—the more iron in a supplement, the less zinc you’re likely to absorb.

My advice: Don’t take a multivitamin that supplies 100% of the “Daily Value” of nutrients, a level intended only to prevent deficiency diseases. Instead, take a multivitamin that supplies an optimal amount of nutrients—an amount that will easily overcome every absorption issue caused by nutrient-nutrient interactions.

For simplicity, use the B-vitamins as your reference point. Look for a product that supplies about 40 milligrams (mg) each of thiamin, ­riboflavin, niacin and vitamin B-6 (pyridoxine), and 200 ­micrograms (mcg) of vitamin B-12. These levels are safe and therapeutic, improving energy and mental clarity. When a product contains the above levels of these nutrients, it usually will have optimal levels of other nutrients as well.

Vitamin mistake #2: You take a dose that’s too high. It can be detrimental to your health to take high doses of vitamin A and vitamin E. Reasons: Taking more than 3,000 international units (IU) of vitamin A (retinol) daily can increase your risk for osteoporosis, the bone-eroding disease. Vitamin E actually is a family of eight compounds called tocopherols and ­tocotrienols. Alpha-tocopherol—the compound commonly found in multivitamins—can be toxic in doses higher than 100 IU daily.

My advice: Take a multivitamin that contains no more than 3,000 IU of vitamin A total, with approximately one-half from retinol and one-half from beta-carotene (which turns into vitamin A in the body and does not cause ­osteoporosis).

Choose a multivitamin with no more than 100 IU of vitamin E. If you take the nutrient as a separate supplement for a specific condition, such as for breast tenderness, take it in the form of mixed tocopherols and ­tocotrienols. 

Vitamin mistake #3: You try to take vitamins two or three times a day. Taking vitamins in divided
doses—two or even three times a day—is ideal ­because the body sustains higher blood levels of the nutrients. But very few people can stick with this type of ­regimen.

My advice: Take vitamins first thing in the morning, with breakfast. (The fat in the meal will help you absorb vitamins A, D and E, which are fat-soluble.) Yes, there’s a tiny trade-off of effectiveness for convenience, but it’s worth it.

Exception: If you take magnesium as a separate supplement, you might want to take it at bedtime for deeper sleep. Avoid magnesium oxide and magnesium hydroxide, both of which are poorly absorbed. Magnesium glycinate or magnesium malate is preferred.

Vitamin mistake #4: You take a ­second-rate formulation. Vitamins come in a range of forms—tablets, caplets, capsules, chewables, softgels, liquids, powders—and some are better than others.

Vitamin tablets, for example, are a poor choice. They may not dissolve completely—and you can’t absorb any nutrients from a pill that doesn’t dissolve. Tablets (and some of the other forms listed above) also may contain binders, fillers and other additives. These supposedly “inert” compounds may have all kinds of unknown effects on the body.

My advice: I recommend powders, which are highly absorbable. Just add water and stir. My favorite is the Energy Revitalization System, from Enzymatic Therapy, which I formulated. (So that I can’t be accused of profiting from my recommendation, I donate 100% of my royalties from sales to charity.) I recommend one scoop each morning combined with 5 grams of ribose (a naturally occurring sugar) to optimize energy.

Don’t like drinks? Try a combination of My Favorite Multiple Take One by Natrol plus two tablets of Jigsaw Sustained Release Magnesium plus two chewable ribose tablets (2 grams to 3 grams each).

Vitamin mistake #5: You take calcium. One-third of people who take supplements take calcium—and I think just about every one of those people is making a mistake. The scientific evidence shows that taking a calcium supplement provides little or no protection against bone fractures, and research now links calcium supplements to increased risk for heart attacks and strokes.

My advice: I strongly recommend that you get your calcium from food, eating one or two servings of dairy a day. Almonds, broccoli and green leafy vegetables such as kale also are good calcium sources. Unlike supplemental calcium, calcium from food is safe. If you decide to take a calcium supplement for stronger bones, take no more than 100 mg to 200 mg daily, and always combine it with other bone-supporting nutrients, such as vitamin D, magnesium and vitamin K. Take these at night to help sleep.

Vitamin mistake #6: You don’t realize that your medication can cause a nutrient deficiency. Some medications block the absorption of specific nutrients. In my clinical experience, the two worst offenders are…

The diabetes drug metformin, which can cause a B-12 deficiency.

What to do: Metformin is an excellent medication, but be sure to take a multivitamin containing at least 200 mcg of B-12 daily.

Proton pump inhibitors such as Nexium (esomeprazole), which block the production of stomach acid and are prescribed for heartburn, ulcers and other gastrointestinal problems. Long-term use can cause deficiencies of magnesium and B-12.

What to do: Take a multivitamin with 200 mcg of B-12 and additional magnesium (200 mg daily)—and talk to your doctor about getting off the drug. (A gradual decrease in dosage is safest.) Proton pump inhibitors are toxic when used long term and addictive, causing rebound acid hyper-secretion when stopped. The solution? Improve digestion using plant-based digestive enzymes, deglycyrrhizinated licorice (DGL), marshmallow root and other stomach-healing supplements. Follow directions on the labels.