Drugs that Cause Nutritional Deficiency

Prescription and Over-the-Counter Drugs can Cause Nutritional Deficiencies

By Ross Pelton, R.Ph., Ph.D., CCN

Many common drugs—both prescription and over-the-counter—can cause nutritional deficiencies that can add to already existing health problems. Instead of healing your problem, the drug only causes more problems. Drug-induced nutrient depletion is a topic that should be important to pharmacists, but most know very little about it. In my book, The Nutritional Cost of Prescription Drugs, I point out that over 1,000 of the most commonly prescribed prescription drugs, and many over-the-counter (OTC) medications, deplete one or more nutrients in humans.

Studies reporting this information have been published in peer-reviewed scientific journals for decades, but since the medical profession believes that, except for gross excess or deficiency, nutrition is of little importance to overall health, the information has been largely ignored. The annual survey of the top 200 drugs in the United States revealed that 15 out of the top 20 prescription drugs in the United States in 1999 are drugs that cause nutrient depletion. Thus, millions of people are taking medications that unknowingly deplete their bodies of essential nutrients.

Commonly Prescribed Drugs that Can Cause Nutritional Deficiencies

  • Oral contraceptives (birth control pills)
  • Estrogen replacement therapy
  • Anticonvulsants
  • Anti-diabetes
  • Anti-hypertensive (blood pressure lowering)
  • Anti-inflammatory (ibuprofen, aspirin)
  • Anti-ulcer and Heartburn drugs (H2 blockers such as Prilosec, Nexium)
  • Cholesterol-lowering drugs
  • Beta-blockers
  • Phenothiazines
  • Tricyclic antidepressants
  • Benzodiazepines
  • Antibiotics

So, you can see that many of the most commonly prescribed categories of prescription drugs can cause nutrient depletion. In this article I will discuss nutrient depletions caused by two categories of commonly prescribed drugs: oral contraceptives and anti-diabetes medications.

Nutritional Deficiencies Caused by Oral Contraceptives (birth control pills)

Back in the mid-1970s, studies reporting that oral contraceptives depleted a variety of nutrients began appearing in the scientific literature. Numerous studies now document the fact that oral contraceptives deplete many of the B vitamins, vitamin C, magnesium, selenium, zinc and the amino acid tyrosine.

Let’s begin by examining the health problems associated with folic acid depletion in women taking oral contraceptives, but please keep in mind that other categories of drugs that also deplete folic acid include antacids, antibiotics, anticonvulsants, biguanide anti-diabetes medications, anti-inflammatory drugs, some of the anti-ulcer medications and aspirin.

Health problems associated with a deficiency of folic acid include anemia, birth defects and cervical dysplasia, which is a pre-cancerous condition characterized by abnormal cells that can be detected in the cervix by pap smear and other methods. Many women with cervical dysplasia end up having a hysterectomy. Sadly, hundreds of thousands of women have hysterectomies every year and many of these surgeries could be prevented if women had adequate folic acid. Other problems associated with folic acid deficiency include depression and increased risk of breast cancer and colorectal cancer.

Three B vitamins, folic acid, vitamin B6, and vitamin B12, are necessary to metabolize the toxic amino acid homocysteine. Elevated levels of homocysteine represent one of the most serious risks to plaque build-up in the arteries and, ultimately, heart attacks. All three of these B vitamins are depleted by oral contraceptives. Thus, women who take oral contraceptives for years may very well be increasing their risk of heart disease.

Vitamin B6 is also necessary for the conversion of tryptophan into serotonin, both important brain chemicals. Thus, oral contraceptive-induced vitamin B6 depletion can inhibit the production of serotonin, which increases a woman’s risks of becoming depressed. In one study, one third of the women taking oral contraceptives for two to five years were found to be suffering from depression. In the brain, serotonin gets converted into melatonin, which is a hormone that helps induce sleep. Therefore, the vitamin B6 depletion caused by oral contraceptives also increases a woman’s risk of developing insomnia and other sleep disorders.

Studies have reported that oral contraceptive use causes a significant decline in vitamin C levels. In one study, women taking both high-dose and low-dose oral contraceptives were evaluated. The results revealed that these women had a decrease in serum levels of vitamin C ranging from 30 percent to 42 percent. Some of the problems associated with vitamin C deficiency include a weakened immune system, poor wound healing and easy bruising.

Studies report that women taking oral contraceptives also have lower serum zinc levels than matched controls. Since zinc is one of the most important nutrients for proper functioning of the immune system, oral contraceptive-induced depletion of zinc may weaken the immune system in susceptible women.

Oral contraceptives also deplete magnesium. Thus, women taking birth control pills will be increasingly susceptible to becoming magnesium deficient. Magnesium deficiency is associated with a greater incidence of osteoporosis, muscle cramps, weakness, insomnia, anxiety and depression, as well as cardiovascular problems, including blood clots, elevated blood pressure, irregular heartbeat, and increased risk of heart attacks.

Nutritional Deficiencies Caused by Anti-diabetes Drugs

Within this general class we have two categories of medications that are of most concern—the sulfonylureas and the biguanides. First we’ll discuss the sulfonylureas including the second best-selling oral diabetes drug glipizide (Glucotrol XL), acetohexamide, glyburide and tolazamide. Studies show that these drugs inhibit enzymes that are necessary for the synthesis of an important antioxidant called coenzyme Q10. (Chlorpropamide and tolbutamide are two members of the sulfonylurea class that do not deplete coenzyme Q10).

Coenzyme Q10 plays a critical role in the protection of mitochondrial DNA, and it also helps prevent the oxidation of LDL cholesterol, so it helps lower cardiovascular disease risks. Low levels of coenzyme Q10 can cause potential problems of high blood pressure, congestive heart failure, low levels of energy and a weakened immune system. The immune system is weakened when you’ve lost the antioxidant potential of coenzyme Q10, which means there is the probability of a substantial increase in free radical damage and accelerated aging.

The study that documented and reported the coenzyme Q10 depletion by sulfonylureas is titled “BioEnergetics in Clinical Medicine: Studies on Coenzyme Q10 and Diabetes Mellitus.” The authors point out that acetohexamide, glyburide, and tolazamide inhibit the coenzyme Q10-dependent enzyme NADH-oxidase. In their conclusion, they state, “…a deficiency of coenzyme Q10 in the pancreas could impair bioenergetics, the generation of ATP, and the biosynthesis of insulin.” This is an important point: These authors are telling us that a coenzyme Q10 deficiency in the pancreas might mean that the pancreatic cells cannot generate enough energy to synthesize insulin. Therefore, diabetic individuals who are taking sulfonylurea drugs are a group of people who should receive special counseling from pharmacists about the importance of taking supplemental coenzyme Q10 on a regular basis.

The only biguanide drug currently available in the U.S. is metformin (Glucophage/Glucovance), but it’s the best-selling oral diabetes drug in the country. Phenformin and buformin are available in other countries, but the former was banned in the U.S. in 1976 because it causes lactic acidosis.

Biguanides have been shown to deplete coenzyme Q10, vitamin B12, and folic acid. The problems with these nutrient depletions have been discussed in the previous sections. However, the vitamin B12 depletion from biguanide medications is a potentially serious nutrient depletion. According to a study in Diabetalogia titled, “Malabsorption of Vitamin B12 and Intrinsic Factor Secretion During Biguanide Therapy,” 30 percent of the diabetic patients in the study had malabsorption of vitamin B12. Withdrawal of the medication resulted in a normalization of vitamin B12 absorption in only half of the individuals with malabsorption. The other half had a permanent depression in intrinsic factor secretion which meant permanently low B12 absorption.

Nutritional supplementation can be used to prevent or overcome drug-induced nutrient depletions. In many cases, this can increase the effectiveness of a medication, reduce the incidence of side effects and contribute to a longer, healthier life.

Nutritional Deficiencies Caused by Anti-ulcer and Heartburn Medications

Anti-ulcer medications are one of the largest selling category of drugs in the pharmaceutical industry, accounting for over six billion dollars in sales in the U.S. There are two main classes of anti-ulcer medication. One group is known as the H2 receptor antagonists or H2 blockers, and more recently a class of drugs known as the proton pump inhibitors have also become very popular. In 1998, the anti-ulcer drug omeprazole (Prilosec) was the top selling prescription drug in the United States, accounting for nearly three billion dollars in sales.

These drugs function by lowering the amount of stomach acid, which can relieve the pain associated with heartburn, acid indigestion and ulcers. However, the level of acidity in the gastrointestinal tract is a critical factor that regulates the absorption of many nutrients. In the process of making the GI tract less acidic, anti-ulcer medications inhibit the absorption of various vitamins and minerals. Studies have reported that H2 receptor antagonists deplete vitamin B12, folic acid, vitamin D, and the minerals calcium, iron, and zinc. There is an added concern because the FDA has allowed them to be taken off prescription-only status. This means people can have unlimited access to these medications without any monitoring or advice from health professionals.

Because the proton pump inhibitors are a newer class of drugs, fewer studies have been conducted regarding nutrient depletions. To date, vitamin B12 is the only drug depletion reported. Some of the health problems related to the depletion of folic acid, vitamin B12 and zinc were mentioned earlier during the discussion of oral contraceptives. Some additional health problems associated with vitamin B12 depletion include anemia, fatigue, depression and, particularly in the elderly, dementia. In severe cases of vitamin B12 deficiency, irreversible nerve damage can occur.

Anti-ulcer drugs are associated with other nutrient depletions as well. Depletion of vitamin D may result in skeletal problems such as osteoporosis as well as muscle weakness, tooth decay and hearing loss. Problems associated with calcium depletion include osteoporosis, heart and blood pressure irregularities and tooth decay. Depletion of iron could result in hair loss, brittle nails and anemia, with accompanying feelings of weakness, fatigue and low energy.


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