The Truth Behind Your Daily Supplements

The lack of federal regulation over supplements prevents them from maximizing patient benefit

By Ananya Dash

Micronutrients such as vitamins and minerals are essential for normal functioning of humans, regardless of sex. In the 1920s, scientists discovered that missing micronutrients in patients’ diets lead to deficiency diseases. In turn, vitamin and mineral capsules — the first supplements —  entered the market to close nutrition gaps in diets. 

Over the years, the definition of supplements has expanded, to now include herbs, animal-derived products, probiotics, hormones, and enzymes. Supplements in the form of pills, powders, liquids, and gummies, numbering into the tens of thousands, even have their own aisles in supermarkets and pharmacies. They promise a healthier lifestyle as wellness products — an insurance against future ailments.

Women have become the largest consumers of these supplements, and, as such, the supplement industry has pursued strategies to target them directly. Their pastel packages are often adorned with long lists of claimed benefits that women are presumed to care about: “strong nails,” “healthy hair,” “glowing skin,” “premenstrual symptoms,” pregnancy, menopause, and more.

Nutrient deficiencies, however, still persist in women. Meanwhile, new research suggests that the women who take supplements are the ones least likely to need them. These health-conscious women likely already eat nutrient-dense foods and have behaviors consistent with existing wellness guidelines. They may also self-prescribe supplements to curtail future ailments, despite limited data that supplements impact overall health.

Evidence to date suggests women of reproductive age should consider self-prescribed supplements in order to fulfill specific micronutrient requirements and avoid health risks during pregnancy. Other than that, however, most women do not need to take supplements, unless a medical condition requires them to do so. 

Nevertheless, with supplements sales persisting, women are struggling to evaluate them.

Vitamin deficiencies and their corresponding medical conditions are not often at the forefront of clinical concern in U.S. patients. “In a doctor’s appointment, there are so many priorities,” says Dr. Mary Scourboutakos, a family medicine resident and nutrition expert at Eastern Virginia Medical School and a public speaker on nutrition science. “Nutrition becomes a sub note among the more pressing concerns.”

For example, insufficient iron intake, excessive loss of blood due to menstruation, or a combination of both can contribute to iron deficiency in women, which affects about 40 percent of females between the ages of 12 and 21 in the US. Despite that prevalence, iron deficiency remains underdiagnosed in women. There are no existing recommendations in the US to regularly screen for iron deficiency with or without anemia, a condition that can develop when iron deficiency is left unchecked, in women of reproductive age. 

Declining iron stores in women has a series of negative health outcomes such as fatigue, shortness of breath, light-headedness, and sleep disturbances. During pregnancy, the risk for anemia rises when the demand for iron increases to supply blood to the developing fetus. The developing child’s brain health can then be negatively impacted if iron levels are not restored in the mother. 

Moreover, a new study published in the journal JAMA Network Open reveals that both pregnant and non-pregnant women in the US have insufficient levels of vitamins A and C, in addition to iron deficiency. The study also showed that there is a decline in consumption of carbohydrate-rich foods among women. Since the 1990s, cereals and grains have been fortified, with added vitamins and minerals, to improve the intake of micronutrients through everyday meals.

“Women are not choosing carbohydrates rich in (micro) nutrients, so we see a decline in iron, vitamin C, and to a lesser extent vitamin A, and in some subgroups, folic acid, which are all important for not only women of reproductive age, but especially for women of reproductive age,” says Derek Miketinas, associate professor of nutrition and food sciences at Texas Woman’s University and the lead author of the JAMA Network Open study.

The Double-Edged Sword of Convenience Foods and Poorly Regulated Supplements

Minimally processed whole foods are rich in micronutrients but they rarely make it to people’s plates, losing out to ultra-processed foods. A recent study published in the journal Nature Food revealed that US grocery stores such as Walmart, Target, and, ironically, Whole Foods are the dominant source of ultra-processed foods.

“We want to start with whole foods but based on our food system, it is difficult to get everything we need in our foods,” says Abbie Smith-Ryan, a professor in the Department of Exercise and Sports Science at UNC Gillings School of Global Public Health. “A blend of whole foods and dietary supplements would be a practical solution.”

Supplements would be a straightforward solution to fulfil micronutrient needs, but they come with several shortcomings. For instance, they generally lack the right levels of ingredients in a tablet as per the daily dietary requirements. Further, supplements fail to carry the indicated amount of ingredients as per the manufacturer’s labeling.

Such discrepancies in supplements stem largely from how the supplement industry is regulated. Supplement makers decide the amount of ingredients they put in, per the Dietary Supplement Health and Education Act, a piece of federal legislation enacted in 1994. Further, the law makes manufacturers — not regulators — responsible for actually including ingredients at the levels labelled on their bottles.

“Consumers need to understand that no one is checking to make sure that the supplements are accurately labeled,” says Dr. Pieter Cohen, an associate professor at Harvard Medical School and an internist at Cambridge Health Alliance. “We are just relying on the company.”

The US Food and Drug Administration regulates supplements as foods, not drugs. As such, manufacturers are not required to prove that their ingredients are safe, or effective in providing the benefits they claim to make. However, supplements can be removed from the market, similar to recent recalls of carrots and Boar’s Head deli meats, if the supplements end up causing serious health issues.

“The rules are really in favoring manufacturers to be able to sell whatever they choose to,” Cohen says. 

Third-party organizations have taken safety designations into their own hands. Groups such as the USP (US Pharmacopeia) and NSF (formerly the National Sanitation Foundation) can help navigate the confusing landscape of the supplement industry by testing and reporting on supplement safety. “If the company has hired [USP or NSF] to take a deep dive into the manufacturing industry, then the supplements contain what’s listed on the label in accurate amounts and do not contain adulterants,” Cohen says.

Paradox of Prenatal Supplements

For years, doctors have recommended that expecting mothers take a prenatal supplement, an umbrella term used to define nutrients such as folic acid, vitamin D, iron, calcium, and DHA, a type of omega-3 fatty acid, that are beneficial for pregnancy.

Among all the recommended micronutrients, folic acid tops the list of recommendations to women of childbearing age. Without the right levels of folic acid, a type of B Vitamin, in mothers, children are born with severe birth defects of the brain and spinal cord. The US Preventive Service Task Force, an independent panel of experts who make evidence-based recommendations, advise women who are planning or are able to become pregnant to take a daily supplement that includes 0.4 to 0.8 milligrams of folic acid.

Requiring all women of childbearing age to take increase their folic acid intake might feel outlandish, but it is a reasonable prevention strategy. The outcomes of folic acid deficiencies in mothers can lead to irreversible deficits in their children, especially in unplanned pregnancies, which make up about half of all pregnancies in the United States.

This approach, however, may be difficult to accomplish in the present supplement landscape. A study published in the American Journal of Perinatology showed that about 30 percent of commercially available prenatal supplements did not have the recommended levels of folic acid. In rare cases, they even contained excessive levels of folic acid, which are with lower levels of cognition in young children. The recommended levels for iron, DHA, and calcium were also unmet. 

Another study published in Maternal Health, Neonatology and Perinatology tested about 180 commercially available prenatal supplements for vitamins and DHA levels. This analysis created further evidence of insufficient multivitamin levels in these products. DHA levels were optimal in just one percent of the supplements. Moreover, vitamin levels were either lower or higher than the required levels – but never optimal. 

“Regulations to ensure that prenatal supplements deliver the nutrients that are needed to obtain the intended benefit would be helpful,” Scourboutakos says.

Such oversight could have meaningful health outcomes. There is evidence, for example, that preterm birth — delivery at less than 37 weeks — reduces with the increase in intake of omega-3s in the mother’s diet. Multiple sources of omega-3s and unpredictable dosage from manufacturers make it harder for Scourboutakos to recommend them to her pregnant patients. She says: “It is impossible to predict which [omega-3 supplement] is going to have the highest quality.”

Many supplements including those recommended to pregnant women fail to meet the standard recommendations, putting the lives of both the mother and the child in jeopardy, despite mothers believing they are doing their best to meet their nutritional goals.

The Current Limits of Health Care

The problems of dietary supplements hardly end at the lack of recommended daily requirements from ingredients, correct labeling, or large-scale clinical trials to prove their health claims. The expansion of the supplement industry instead hints at a fractured medical system, especially for women.

“We need more research in women to really have an evidence-based approach to recommend supplement doses,” says Smith-Ryan. “The majority of our health care system, and even dietary supplements, are based on research in men.”

The popularity of supplements lies in the false promises that the industry makes to fix possible health issues in women, even those that don’t yet have such diagnoses. Supplements, however, can hardly undo the harms of poor lifestyle: lack of whole foods, exercise, and proper sleep.

“We all want to believe in silver bullets,” Scourboutakos says. “Unfortunately, you have to chop the vegetables. It takes time, but data consistently shows that the shortcut doesn’t give you the same outcome as the food itself.”