Plant-based diets: Researchers highlight importance of supplements during perinatal period

08 Dec 2023 --- International researchers suggest that over-the-counter supplements can reduce vitamin insufficiencies in women during preconception, pregnancy and lactation. They also caution that at the start of their trial, over 90% of participants had marginal or low concentrations of one or more nutrients — folate, riboflavin, vitamin B12 and vitamin D — while many developed markers of vitamin B6 deficiency in late pregnancy. 

In the clinical trial, researchers assessed blood plasma levels of women at preconception, in early and late pregnancy and post-delivery. Half of the 1,729 participants received standard vitamin supplements, while the other half consumed an enhanced vitamin supplement. 

Consuming a preconception or pregnancy supplement substantially reduced the prevalence of vitamin deficiency and depletion markers before and during the pregnancy. 

“Our study shows that almost every woman trying to conceive had insufficient levels of one or more vitamins, and this figure is only going to get worse as the world moves toward plant-based diets,” says lead author Keith Godfrey, professor of epidemiology at the University of Southampton, UK. 

“People think that nutrient deficiency only affects people in underdeveloped countries — but it also affects most women living in high-income nations.”

Mellor critiques that the paper does not report any health changes in pregnant women or the health of their babies.No health changes reported 
Dr. Duane Mellor, registered dietitian and senior lecturer at Aston University, UK, objects that the paper “does not report any health changes experienced during pregnancy or how healthy the babies were when they were born.”

“It suggests that women and their babies might be at risk due to dropping levels of vitamins (especially vitamins B6, B12 and D) and minerals (especially iodine) during pregnancy. Although some of this drop might be explained by an increase in the amount of blood (plasma) which expands during pregnancy, the authors claim that the drop in levels may represent a level of deficiency.” 

Moreover, Mellor highlights that several of the study’s researchers were co-investors with Nestlé for the supplement used in the study, containing not only B vitamins, vitamin D, zinc and iodine but also moo-inositol and probiotic bacteria. 

“It might be seen as a potential conflict of interest that the researchers are co-inventors of the supplement with a large multinational food company.” 

“This concern might be increased given that unlike earlier studies of vitamin supplements which showed folic acid (folate) reduced the risk of spina bifida and neural tube defects, this study did not show any benefits for the mother or baby.” 

Enhancing supplements 
The study, published in PLOS Medicine, assessed blood plasma levels of 1,729 women aged 18-38 from the UK, Singapore and New Zealand at preconception. The researchers also analyzed plasma vitamin levels in early and late pregnancy for 580 participants, of which 512 women’s plasma levels were assessed six months post-delivery. 

The researchers randomized the trial participants into two groups, consuming either a standard or enhanced vitamin supplement twice daily until delivery of the baby. 

Formulations for both groups included folic acid (400 μg/day), iron (12 mg/day), calcium (150 mg/day), iodine (150 μg/day) and β-carotene (720 μg/day). 

In addition, the intervention group’s supplements included riboflavin (1.8 mg/day), vitamin B6 (2.6 mg/day), vitamin B12 (5.2 μg/day), vitamin D (10 μg/day), zinc (10 mg/day), myoinositol (4 g/day) and probiotics (Lactobacillus rhamnosus and Bifidobacterium animalis sp. lactis).

The researchers suggest that supplements can reduce vitamin insufficiencies in women during preconception, pregnancy and lactation.Vitamin levels 
In control group participants, plasma concentrations of riboflavin declined throughout their pregnancy, vitamin D concentrations were unchanged in early pregnancy, while levels of vitamins B6 and B12 declined. The researchers note that 54.2% of control group participants developed a low late-pregnancy vitamin B6 concentration in their plasma. 

After one month of supplementation, participants in the intervention group had substantially higher concentrations of riboflavin and vitamins B6, B12 and D. These levels were maintained during pregnancy. 

In addition, the intervention group had lower vitamin insufficiency or deficiency markers. At the same time, the proportion of participants with vitamin D insufficiency (<50 nmol/L) during late pregnancy was also lower in this group. Vitamin B12 levels remained higher in the intervention group than in the control group six months after they stopped supplementation. 

Reducing deficiencies 
Wayne Cutfield, professor of pediatric endocrinology at the University of Auckland, New Zealand, and co-author of the study, recommends that expecting mothers be given over-the-counter multivitamins to reduce nutrient deficiencies. 

He adds: “The well-being of a mother before conceiving and during a pregnancy directly influences the health of the infant, their lifelong physical development, and ability to learn.”

Although Mellor agrees that pregnant women should consume additional folate, vitamin D and iodine, it “is important not to take too much of any one vitamin or mineral as high doses of some can be potentially harmful, especially vitamin A.”

“Apart from folic acid (folate), which has recommended doses of 400 micrograms a day for most women, it is not recommended to take more than the recommended daily amount of any other vitamin or mineral.”

Earlier this year, US-based researchers determined that only one out of 20,547 supplements on the US market contained target doses for six essential nutrients during pregnancy — vitamins A and D, folate, calcium, iron and omega-3. The latter two had the greatest insufficiencies. 

The study’s authors are concerned that plant-based diets could increase the rate of vitamin deficiencies.Plant- vs. animal-based 
The study’s authors are concerned with the growing rates of plant-based food consumption and the prevalence of vegan diets, as they note that these may increase the rate of vitamin deficiencies among women attempting to become pregnant. 

“The push to reduce our dependence on meat and dairy to achieve net-zero carbon emissions is likely to deplete further expecting mothers of vital nutrients, which could have lasting effects on unborn children,” asserts Godfrey. 

Co-author Shiao-Yng Chan, associate professor at the National University of Singapore, adds: “If we continue to move toward diets with less meat and dairy products, reducing intakes of micronutrients essential for a child’s development, vitamin deficiencies will continue to grow unless women start taking more supplements or are supported with specific advice about nutrient-rich foods.”

In his reaction to the study, Ian Givens, professor of food chain nutrition and director of the Institute for Food, Nutrition and Health at the University of Reading, UK, hopes it will provide an “impetus to reassess dietary provision of key nutrients before and during pregnancy.” 

He explains that animal- and fish-based products provide a large share of dietary vitamins B12 and D, although supplementation is also needed for vitamin D. 

“As the authors suggest, the current trend toward diets with animal-derived foods being at least partially replaced by plant-based foods will further increase the risk of sub-optimal status of vitamin B12 and D (and other nutrients) in women of childbearing age. This needs to be considered when such dietary transition is contemplated.”

To fill a market gap, US-based wellness brand Future Kind developed a vegan prenatal vitamin supplement tailored to expecting mothers on a plant-based diet. The product contains vitamins B12 and D3, methylfolate, iron, choline and DHA from algae. 

Meanwhile, research in the Netherlands revealed that several plant-based meat alternatives scored better than comparable animal meat products in terms of protein, salt, sugar and fat content. Of the products examined, 15% of meat substitutes and 17% of animal reference products met nutrition criteria for iron, vitamin B12 and protein. 

By Jolanda van Hal