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Recent developments in France have brought attention to the labeling of Vitamin D as an endocrine disruptor (ED). French authorities have proposed warning labels on products containing more than 0.1% cholecalciferol by weight, following its classification as an ED. This move, though aimed at consumer awareness, has raised concerns about the potential for decreased consumer trust and consumption of Vitamin D, despite its crucial health benefits. This recent news development feels like a perfect example of why midlife women need to be able to decode the science to make health decisions for themselves instead of relying on agencies and journalism, as we discussed in episodes 8 and 9, “Let’s Talk About Science.”
This article will discuss the functions of Vitamin D in the body, how much women in midlife need of this crucial nutrient, and sources in our environment, diet, and supplementation. We’ll briefly look at the differences in sources. We will also examine the interactions of estrogen with Vitamin D and how the fluxing nature of estrogen in perimenopause can impact its functions and bioavailability during the menopause transition. Finally, we will consider a targeted approach to supplementation and why it’s necessary to test and not guess.
Vitamin D, a fat-soluble vitamin, plays a vital role in our health. It’s found in certain foods, added to others, available as a supplement, and synthesized in the skin upon exposure to sunlight. Unlike other vitamins and cofactors, it functions as a hormone, in that it is involved in cell signaling. Its primary functions include promoting calcium absorption for normal bone mineralization and growth, reducing inflammation, and supporting cell growth, neuromuscular and immune function, and glucose metabolism. It exists in two main forms: D2 (ergocalciferol) and D3 (cholecalciferol), both well absorbed in the small intestine. The primary natural sources of Vitamin D are fatty fish, fish liver oils, and, to a lesser extent, beef liver, egg yolks, and cheese. Fortified foods like milk and breakfast cereals also contribute significantly to Vitamin D intake in many diets. Sunlight exposure plays a crucial role in Vitamin D synthesis in the skin, though factors like season, skin melanin content, and use of sunscreen affect this process.
The active form of Vitamin D is D3, or cholecalciferol. French authorities propose labeling products that are made up of more than 0.1% D3 with the statement: “contains the substance Cholecalciferol. This substance has health benefits when used according to the precautions and dosages on the package leaflet or product labeling. If in doubt, seek the advice of a health professional.”
We will discuss why this verbiage can be misleading and damaging later.
Vitamin D3 interacts with estrogen in a number of important ways. Vitamin D can induce the activity of certain enzymes, such as CYP3A4, which are involved in metabolizing various substances, including estrogen. This induction might affect estrogen’s bioavailability and potentially alter its levels and effects in the body.
Both vitamin D and estrogen play significant roles in maintaining bone health and calcium homeostasis. Estrogen helps regulate bone density and turnover, while vitamin D is crucial for calcium absorption and bone formation. Vitamin D has been found to influence the expression of estrogen receptors. This means that vitamin D can affect how cells respond to estrogen, which is vital in tissues that are sensitive to estrogen, such as breast tissue.
There is some evidence to suggest that vitamin D and estrogen may jointly influence the risk of certain cancers, such as breast cancer. Vitamin D is thought to have a protective effect, possibly by modulating the effects of estrogen on breast tissue.
Vitamin D deficiency can lead to serious health issues like rickets in children and osteomalacia in adults. The National Academies of Sciences, Engineering, and Medicine (NASEM) have set Recommended Dietary Allowances (RDAs) for different age groups to maintain bone health and normal calcium metabolism. For instance, for adults over 70 years, the RDA is 20 mcg (800 IU). However, obtaining sufficient Vitamin D from natural food sources alone can be challenging, necessitating the need for fortified foods, supplements, and sunlight exposure.
Bioavailability must also factor into the conversation, as the type and source of the nutrient impacts our ability to absorb and use it, as does our life stage. For example, fat-soluble vitamin D is optimally absorbed when it is accompanied by dietary fat. It is found in its active D3 form in animal sources. While plant sources of Vitamin D are D2, or ergocalciferol, which is absorbed well in the small intestine, it is bound by phytates and other plant constituents that are difficult to break down during digestion. Certain drugs also interfere with absorption.
There are bodily factors that impact bioavailability as well. For example, celiac disease and other gastrointestinal conditions can impact absorption. Body composition plays a role as well, as D3 can be sequestered in adipose tissue and therefore not available for its functions in cases of obesity. Because dietary D needs to be activated by enzymes in the liver and kidneys, conditions impacting these organs also impact bioavailability of the nutrient.
Because of the complex interactions between estrogen and Vitamin D, estrogen’s fluxing nature and subsequent decline during the menopause transition impacts Vitamin D’s bioavailability and function as well. In fact, while further study is needed, there is mounting evidence that Vitamin D may influence menopausal symptoms. Additionally, aging skin impairs the body’s ability to synthesize Vitamin D. Therefore, midlife women are likely impacted by these bioavailability and function issues.
While deficiency carries its own set of risks, fat-soluble Vitamin D can build up to toxic levels if overconsumed. Upper Limits (UL) are designated by NASEM as lowest level at which no harm will be done. In menopausal women, overconsumption of Vitamin D, particularly in supplements, can cause renal problems such as kidney stones and hypercalcemia.For this reason, midlife women should consult their doctor to test Vitamin D levels before starting a supplement regimen.
The French decision to label Vitamin D as an ED is part of an effort to inform consumers about disruptors in products. This decision could affect consumer trust in Vitamin D supplements, despite the clarification that cholecalciferol’s health benefits are realized when used as directed.
The proposed statement’s wording is also misleading in several ways. First, the technical name cholecalciferol is not commonly used or known by most consumers. Not only is this word choice, as opposed to “Vitamin D” confusing and opaque, it can cause alarm. Secondly, the labeling refers to cholecalciferol as a “substance” – another scary word reminiscent of a drug or non-food … well, substance. Vitamin D is a vitamin, sourced in foods as previously described. Finally, the label states that cholecalciferol “has health benefits,” which, while true, is incomplete. It fails to point out that cholecalciferol – Vitamin D – is a necessary nutrient involved in a variety of important functions.
While the French authorities’ decision aims to increase transparency about endocrine disruptors, it’s crucial to understand the context and the established health benefits of Vitamin D. Adequate intake of Vitamin D is vital for bone health, immune function, and overall well-being. Consumers, particularly midlife women, should be aware of the importance of Vitamin D as well as deficiency risks and the specific disruptions of the perimenopausal hormonal milieu. Critically consider the recommended dietary intakes, food sources, and the role of sun exposure in maintaining adequate Vitamin D levels. If concerns arise, consulting a health professional for personalized advice is advisable.