Why base One contains no vitamin D

A complete multivitamin that leaves out vitamin D is surprising at first glance, and the question deserves a full answer. Vitamin D occupies a singular position among micronutrients: a fat-soluble hormonal precursor whose need varies enormously between individuals. Three converging facts explain the choice: hormonal status calls for an individual dose guided by blood analysis, fat-solubility calls for a lipid vehicle that a water-soluble powder does not provide, and seasonality calls for a modulation that a fixed dose ignores.

Vitamin D is not a nutrient like the others

Its journey follows a three-step chain. Skin exposed to UVB converts 7-dehydrocholesterol into cholecalciferol. The liver performs a first hydroxylation (CYP2R1) and produces 25-hydroxyvitamin D, or calcifediol, the storage and transport form that serves as the reference blood marker. The kidney performs the second hydroxylation (CYP27B1) and produces calcitriol, the biologically active form.

Calcitriol binds the VDR receptor, a nuclear receptor present in nearly all human tissues, dimerises with RXR, binds DNA and regulates the transcription of several hundred genes (Carlberg & Campbell 2013). A molecule that acts on genome expression through a nuclear pathway follows a hormonal logic, with fine regulation and a need that belongs to each individual. This characteristic drives the whole reasoning that follows.

Why vitamin D deficiency is so common in Switzerland

Switzerland sits between 46 and 47 degrees north. At that latitude, the sun's zenith angle becomes insufficient from October to March for UVB to reach the ground in useful amounts: skin synthesis stops for six months, whatever the exposure time. Other factors add up: indoor living reduces even summer exposure; fat mass sequesters this fat-soluble molecule; darker phototypes produce less at equal exposure; and skin 7-dehydrocholesterol declines markedly after 65. The Swiss Federal Commission for Nutrition documented the situation in its vitamin D report, and the CoLaus study in Lausanne confirms the scale of the phenomenon in the Swiss population.

D2 or D3: two distinct molecules

Ergocalciferol (D2) comes from the ergosterol of yeasts, mushrooms and UV-exposed plants. Cholecalciferol (D3) comes from 7-dehydrocholesterol; vertebrates synthesise it in their skin. Both follow the same hydroxylation route to calcitriol and both are safe. The difference appears at the finish line, in the amplitude and duration of the calcifediol rise: Armas et al. (2004) measured a clearly superior potency for D3; Houghton and Vieth (2006) documented its higher affinity for the DBP transport protein, slower clearance and longer half-life; the Tripkovic meta-analysis (2012) confirmed D3's superiority in raising blood status. Human metabolism has adjusted to this form over millennia of animal-based food. D3 is the form to prefer, in every dietary configuration.

Vegan-accessible vitamin D3

Two routes provide cholecalciferol without lanolin. Boreal lichen (notably Cladonia rangiferina) contains 7-dehydrocholesterol converted into cholecalciferol by UV exposure: an authentic plant-derived D3 with full traceability and industrial-scale extraction. Controlled enzymatic synthesis and irradiation produce a high-purity cholecalciferol chemically identical to the one human skin makes; structural identity is the only criterion that matters biochemically. A vegan choice therefore comes with full access to D3.

Why one dose for everyone would make no sense

Here is the heart of the question, and the main reason for the absence in base One. The need depends on determinants that vary strongly between people: baseline blood level, body weight, fat mass, current season, latitude, skin phototype, age, VDR and CYP2R1 polymorphisms, associated treatments. What a 100 kg man needs in February differs by a wide factor from what suits a 55 kg woman in July.

The coherent approach is to measure, then adjust: a baseline 25-hydroxyvitamin D test, a re-test after three months of supplementation, and a calcium check. Professor Vincenzo Castronovo, a pioneer of functional medicine and founder of the Metastasis Research Laboratory at the University of Liège, places the ideal target above 60 ng/mL and recalls that the Mayo Clinic proposes a 50 to 100 ng/mL range, which leaves most of the population below the optimal level. He also notes that 25 ng/mL, considered sufficient to prevent rickets, remains insufficient for optimal immune function, which many micronutrition experts place at 50 ng/mL.

Field orthomolecular practice works with higher targets: the useful interval observed in consultation sits between 80 and 100 ng/mL (200 to 250 nmol/L). This range comes from accumulated clinical observation; studies are under way and their results are pending. It is built under analytical control, with guidance from a practitioner trained to read these panels.

How to take vitamin D properly alongside base One

Fat-solubility dictates the mode of intake. Intestinal absorption uses biliary micelles, the route of dietary lipids; without fat in the meal, micelle formation stays limited and the absorbed fraction drops accordingly. Dawson-Hughes et al. (2015) measured a substantial rise in absorption when intake accompanies a fat-containing meal. The right vehicles are good fats: virgin olive oil, nuts, fatty fish, egg yolk. The right format follows the same logic: oily capsule, softgel or oily drops, with the fattiest meal of the day.

This requirement directly explains the absence of vitamin D in base One. The formula is an isotonic powder dissolved in a glass of water, an aqueous medium that provides no lipid vehicle. A D3 added to this matrix would see its absorption depend entirely on the accompanying meal, with a variability nothing controls. Putting a molecule on a label implies guaranteeing its entry into the body. The same reasoning extends to the other fat-solubles: omega-3s and vitamin K2 (MK-7) follow the same principle and the same intake rules, as a logical complement to the daily water-soluble base.

The iron parallel: what we leave out, and why

base One also leaves out iron and copper, because of absorption competition at the intestinal DMT1 transporter they share with zinc: simultaneous presence in one intake would produce mutual inhibition (see vitamin and mineral antagonisms). The formula acts indirectly: vitamin C at 580 mg and beta-carotene support the absorption of dietary non-heme iron. Three absences, three documented reasons, one formulation rule: every molecule on the label must be assimilable in the chosen matrix and compatible with its neighbours. Transparency about what is absent is the best guarantee of the value of what is present.

FAQ

When should you take vitamin D?

With the meal containing the most fat, at whatever time suits you. Regularity from October to March is the decisive parameter at our latitudes.

Vitamin D3 or D2?

D3, cholecalciferol, raises blood levels more strongly and durably. It exists in a plant version from boreal lichen, accessible to vegan diets.

What blood level of vitamin D should you aim for?

The marker to request is 25-OH vitamin D. The target is defined with a practitioner trained in micronutrition, based on the baseline result and the individual context.

David Giovenco · Micronutrition researcher · President, Académie Internationale Francophone de Médecine Orthomoléculaire et Intégrative · Founder & Formulator, nuho

Sources

Armas 2004 (J Clin Endocrinol Metab) · Houghton & Vieth 2006 (Am J Clin Nutr) · Tripkovic 2012 (Am J Clin Nutr, méta-analyse) · Carlberg & Campbell 2013 (Steroids) · Dawson-Hughes 2015 (J Bone Miner Res) · Commission fédérale de l'alimentation 2012 (OSAV) · Guessous et al., étude CoLaus, Lausanne · Castronovo V., entretien avec M. Kaplan (2019) ; podcast Symp, laboratoire LIMS (2025).