The amount of supplements offered in local pharmacies and supermarkets is often enough to grant them their own aisle, full of brightly-colored bottles of all shapes and sizes promoting the wellness of hair and nails, the heart, sleep or bones. There are options for men and women, kids and “over 50s” in pills, powders or gummy formulations. Decades of research shows that getting the right amount of certain vitamins and minerals in the diet can ward off diseases, and dietary guidelines serve as the most accurate estimate we have for what the body needs to stay healthy.
But some say more research is needed to fully understand sex differences in how female and male bodies need and use these nutrients across the life cycle. As a result, some are calling for improved recommendations that take a closer look at the role that sex, hormonal changes, and body composition play into these nutritional needs.
“Women live longer, they experience different things like pregnancy and lactation, menstruation and menopause, and they have different disease risks,” said Dr. McKale Montgomery, a nutritionist at Oklahoma State University. “But so often the difference between the men versus women’s [supplements] is the color of the bottle and not what is inside.”
Although people had been using herbal medicines to supplement nutrients in their diet for centuries, Polish biochemist Casimer Funk is credited with coining the term "vitamins" in 1920, referring to the substances not produced in the body that we supplemented by diet. (“Vita” means “life” in Latin and “amine” is a nitrogenous substance necessary for biological life.) Funk’s research also showed that the lack of certain vitamins would cause illness, including a disease called pellagra when the body lacked vitamin B3 and scurvy when it lacked vitamin C.
This work culminated in nutritional guidelines in the U.S. called the Dietary Reference Intake (DRI) values published at the turn of the 21st century that identify the amount of dozens of vitamins, macronutrients and minerals the body needed.
"So often the difference between the men versus women’s [supplements] is the color of the bottle and not what is inside."
Several sex differences have been well-researched and are reflected in the guidelines. Women of reproductive age are recommended to take more iron at certain ages, and women, particularly in the postmenopausal period of life, are recommended to take more calcium for bone health. Men, on the other hand, are recommended to take more magnesium and zinc. In general men are recommended to take a greater quantity of many vitamins simply based on differences in body composition.
However, some have called for more research in women specifically in the dietary supplement space, said Dr. Abbie Smith-Ryan, a professor of exercise physiology at UNC Chapel HIll. Although women consume more supplements than men, supplement use hasn’t been as well studied in women, she explained.
“The majority of data, if there is data, is done in young men for many reasons,” Smith-Ryan told Salon in a phone interview. “That doesn’t mean that everything needs to be at different doses, but at the very minimum, we need to understand: Should those be recommended at a different dose or with different ingredients to enhance absorption, or some of those things.”
The National Institutes of Health acknowledged the need for more nutritional research for women in its 2020-2030 strategic plan, which listed nutritional differences in women, along with differences in nutritional needs during pregnancy and lactation and across a woman’s life cycle as some of its research priorities.
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“Nutrition plays an important role in many diseases and conditions that primarily affect women or that affect women differently than men,” it states. “Inherent within this plan and its implementation are research approaches and activities that address the roles of sex and gender in health and disease; promoting participation of women in clinical nutrition research; and integrating sex as a biological variable in basic, preclinical, and translational nutrition research.”
Instead of comparing men and women to understand differences in nutritional needs, it might be more useful to study how nutritional needs vary across a woman’s life cycle, Smith-Ryan added.
“No two women have the same menstrual cycle or hormone profile … so the standardization is much harder and requires more time and money to capture,” she said.
One particular population that nutritional differences are more pronounced is athletes, in whom getting the right nutrients can also reduce the risk of injury. While female athletes are less likely to not get adequate nutrients, they are also more likely to see the consequences of that, Smith-Ryan said.
“Anytime you add in that extra stress and those extra caloric needs from exercise, you see more of an impact, meaning, if you're low on vitamin D or iron, you're going to feel that,” Smith-Ryan said. “Whereas, if you're more of a sedentary individual, you may not feel those as much because you're not stressing the body the same way.”
There is also limited research available on which supplements might help women during the perimenopause part of life in particular. Some evidence suggests B12 might be helpful to the nervous system and vitamin D is helpful for promoting bone growth. Magnesium might help with sleep problems, although the research behind many of these links is thin and the recommendations for these supplements don't currently differ by sex for this age group.
“Refining our recommendations for that decade would be really helpful,” Smith-Ryan said.
Vitamin D and calcium have been recommended among older adults to promote brain and bone health, especially among women who are affected by osteoporosis at four times the rate as men.
However, a draft recommendation by the United States Preventive Services Task Force released last month actually recommended against taking these two supplements at this age for both sexes for the purpose of reducing fractures. Although the agency clarified that supplementation with vitamin D and calcium could still be important for this age group for other reasons, some disagreed with the recommendation, noting that it didn’t take into account individual differences in whether people had vitamin D deficiencies.
“Dismissing supplementation as unnecessary for the general population undermines its value for those who need it most,” said Dr. Andrea Wong, the senior vice president of scientific and regulatory affairs at Council for Responsible Nutrition, a trade organization that represents many supplement manufacturers, in a statement.
In general, nutritional changes to help menopause would work better if they began long before menopause anyways, said Dr. Mary Scourboutakos, a family doctor with a PhD in nutrition. For example, peak bone mass is determined in the teenage years, meaning vitamin D and calcium intake many years before menopause is what is important for bone health at that time, she said.
“We tell women when they’re 60 years old that their bone mass is low and try to pump them full of calcium and vitamin D,” Scourboutakos told Salon in a phone interview. “But the reality is, it’s the calcium and vitamin D they didn’t have in their teenage years that lands them in this place in their 60s.”
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While drugs are used to treat illness, nutrition’s purpose is generally to prevent it, Scourboutakos said. However, this operates in a different research paradigm than how the effectiveness of drugs are demonstrated. While drug research takes sick people to determine whether a drug works, supplement research often takes healthy people and sees whether supplements can prevent illness.
“It’s easier to prove that you treated something than if you prevented something, and nutrition often works over years and decades, so it’s hard to get research to fund such a study,” Scourboutakos said. “Everything about our scientific method makes it hard to prove these sorts of things.”
Supplements are regulated for safety but not efficacy by the 1994 Dietary Supplement Health and Education Act, which is enforced by the Food and Drug Administration. The FDA and the Federal Trade Commission monitor companies to ensure they are actually selling what is being advertised, said Steve Mister, president and CEO of the Council for Responsible Nutrition.
“We have our own requirements that I would classify as being somewhere between those for food and those for drugs,” Mister told Salon in a video call.
The way the current regulations work provides the industry with greater flexibility so that it can react more quickly to changes in research, Mister said.
“It’s left to the market to create the variability in formulations," Mister said. “That’s the beauty of the law that allows us to have some flexibility in how we develop the formulas for the products.”
Still, others have called for more regulations on supplements as the number of people taking them has exploded in recent years — with as many as 4 in 5 people reporting using them at some point in their lives.
In pregnancy, women are recommended to take prenatal vitamins to ensure the body gets the right amount of folate, Omega-3 oils, and choline, among other vitamins like iron, vitamin D, and calcium. Although this population is one that has been studied to determine the benefit of these supplements, recent research has shown that many of these essential nutrients are missing from some products on the shelves.
One study found none of close to 50 samples of commercially available prenatal vitamins contains all of the recommended supplements for pregnant women, and up to 27% had less than the recommended amount of folate, which has been shown to protect against birth defects.
Ultimately, it’s largely up to the individual to stay up-to-date with their nutrient needs and make sure they check nutritional labels to ensure they are getting what they need from the supplements they do or not decide to purchase.
“A lot of time women don’t get that support or our health care providers don’t know the data,” Smith-Ryan said. “We need to encourage women to take care of themselves and advocate for themselves.”
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