What scientific evidence supports the ingredients in SANA Nutrients

Scientific evidence in supplementation is not generated for brands, but for specific ingredients, their chemical forms, the doses used, and the physiological context in which they are studied.

When someone searches for studies on a supplement brand and cannot find any, the most frequent conclusion is that "there is no evidence." That conclusion is a methodological error. Clinical trials, systematic reviews, and clinical guidelines are not designed to validate brand names: they are designed to study nutrients, compounds, and physiological mechanisms.

The question that really matters is another: does this formula use ingredients whose chemical form, dose, and context of use are supported by independent scientific literature?

Applying that criterion requires knowing what type of evidence exists, how to read it, and what signs indicate that a formulation respects it. This article applies that framework to the key ingredients in SANA's catalog, without becoming a product sheet or a promise of results.

To evaluate whether a supplement has real scientific backing, it is advisable to review:

• Whether the active ingredient has been studied independently in humans, at what dose, and in what population.

• Whether the chemical form used (salt, ester, active form) has bioavailability or comparative studies.

• Whether the doses used align with those used in the studies or with the recommendations of organizations such as the NIH Office of Dietary Supplements or the EFSA.

• Whether the formulation acknowledges the limits of the evidence rather than promising universal results.

That is the standard that is applied below.

What type of evidence exists in supplementation and which carries the most weight

Not all evidence carries the same weight. In nutrition and supplementation, there is a methodological hierarchy that allows us to distinguish between solid signals and preliminary findings. Knowing it helps to read any study with more discernment.

Type of evidence	What it provides	Key limitations
Controlled clinical trial (RCT)	Causal relationship between ingredient and outcome in humans	Depends on the dose, duration, population, and design; costly to replicate in micronutrients
Systematic review and meta-analysis	Synthesis of multiple trials; greater statistical power	Only as good as the studies included; heterogeneity between studies can distort results
Bioavailability study	Compares absorption and utilization between different chemical forms	Does not always correlate with clinical effect; many are short-term
Observational study	Associations between habitual intake and health status	Does not establish causality; confounded by diet and lifestyle
Clinical guideline	Translates accumulated evidence into practical recommendations	Reflects consensus, not always the most recent evidence; varies between organizations

Why clinical guidelines are especially relevant in female supplementation

Guidelines from organizations such as NICE, the NIH, or the EFSA are not marketing documents: they are syntheses of peer-reviewed evidence, subject to periodic updates. When a guideline recommends folate before and during pregnancy, or vitamin D during gestation, it does so because the accumulation of trials and observational data consistently justifies that recommendation.

For ingredients such as magnesium, vitamin D, or iron, there is a solid body of literature that allows for reasoned statements about physiological function, dosage guidelines, and populations with greater need. For other ingredients, such as some botanicals or adaptogens, the evidence is more heterogeneous and requires more caution in conclusions.

The key is not to look for the perfect study, but to understand what type of evidence supports each ingredient and with what degree of certainty. That is what is analyzed in the following blocks.

Magnesium: why the form matters as much as the mineral

Magnesium is one of the micronutrients with the largest body of research in humans. According to the NIH Office of Dietary Supplements, it participates in more than 300 enzymatic reactions, including protein synthesis, muscle and nerve function, glycemic regulation, and energy production. That breadth of physiological function is precisely the reason it appears in so many formulas, and also the reason it is advisable to carefully read what chemical form is used.

Magnesium forms are not equivalent

The form of magnesium determines its absorption, digestive tolerance, and, to some extent, its tissue distribution. Not all magnesium supplements are comparable, even if the elemental amount indicated on the label is similar.

Form	Estimated absorption	Digestive tolerance	Most studied context of use
Bisglycinate	High (amino acid chelate)	Very good; minimal laxative effect	Neuromuscular function, sleep, stress
Citrate	Good	Good; may have a laxative effect at high doses	Intestinal transit, muscle function
Acetyl taurate	Moderate-high	Good	Neurological function, blood-brain barrier
Oxide	Low (~4%)	Variable; frequent laxative effect	Use as an antacid; inefficient for deficiency

 

Bioavailability studies published in journals such as Nutrients (PMID: 36986196) suggest that bisglycinate and citrate have higher absorption rates than oxide under comparable conditions. This has direct implications for the actual effective dose that reaches the tissues.

What the literature says, with nuances

Evidence on magnesium and menstrual pain has gained consistency in recent years: a 2024 meta-analysis published in Pain Medicine identified a reduction of between 30 and 50% in pain intensity in supplemented women compared to placebo. Data on sleep and stress are promising, although more heterogeneous in design and population.

What this means in practice: the scientific argument for a formula like Triple Magnesium is not that "magnesium cures," but that combining forms with different absorption and tolerance profiles has a physiological logic supported by the literature. The choice of bisglycinate, citrate, and acetyl taurate along with vitamin B6 responds to criteria of bioavailability and function, not marketing trends.

Consult the SANA ingredients page to see the specific forms and doses used in each formula.

Vitamin D3 + K2: evidence of synergy, but with context

Vitamin D is one of the nutrients with the largest volume of clinical research in the last two decades. The NIH Office of Dietary Supplements documents its role in calcium and phosphorus homeostasis, bone mineralization, immune function, and the regulation of numerous genes. Deficiency is prevalent in populations at middle and high latitudes, especially in months of low sun exposure.

Vitamin K2, for its part, acts as a cofactor in the activation of vitamin K-dependent proteins, including osteocalcin (involved in calcium deposition in the bone) and matrix GLA protein (involved in the inhibition of arterial calcification). Its mechanism physiologically complements that of vitamin D3.

What we know and what we do not know yet

	Vitamin D3	Vitamin K2 (MK-7)	D3 + K2 combination
Strongest evidence	Bone health, immune function, deficiency in pregnancy	Bone metabolism, osteocalcin activation	Improvement of bone mineral density in postmenopausal women (trials 2024-2025)
Promising evidence	Muscle function, mood in deficiency	Management of vascular calcium	Greater joint efficacy than separately in musculoskeletal health
Still uncertain	Broad cardiovascular benefits in the population without deficiency	Long-term bone-independent effects	Optimal dose of K2 to maximize synergy

 

What this implies for the reader:

• Vitamin D3 makes more sense when there is a risk of deficiency or insufficient intake, something especially frequent in Spain between October and March.

• The combination with K2 in MK-7 form has a coherent physiological justification, although the degree of benefit depends on the baseline nutritional status.

• NICE guidelines recommend vitamin D supplementation during pregnancy, which reinforces its relevance in specific physiological stages.

• A formula like Vitamin D3 + K2 should be evaluated based on each person's starting status, not as a universal solution.

The dose used, the origin of vitamin D3 (in this case from lichen, of plant origin) and the form of K2 (MK-7, with a longer half-life than MK-4) are variables that the literature considers relevant for efficacy.

Digestive and liver ingredients: when evidence is useful and when to be cautious

Formulas aimed at digestive and liver wellness usually combine botanical extracts with amino acids and micronutrients. In this block, the evidence is more heterogeneous than in the case of magnesium or vitamin D, and transparency about its limits is a sign of rigor, not weakness.

Evidence by main ingredient

Curcumin (standardized turmeric extract)

• Curcumin has antioxidant and inflammatory response modulating properties well documented in cell models and some human trials.

• Recent systematic reviews on PubMed identify improvements in inflammation and oxidative stress markers, with a more consistent effect when used in forms with improved bioavailability (such as the combination with piperine or in liposomal formulations).

• The evidence on specific liver parameters is promising, but human studies are still limited in sample size and duration.

Silymarin (milk thistle extract)

• Silymarin is the active compound of milk thistle and acts mainly as an antioxidant at the liver level.

• A broad review collected in medical literature shows significant improvements in liver enzymes (ALT, AST) in patients with non-alcoholic fatty liver disease. The studied dose usually ranges between 140 and 600 mg/day of standardized extract.

• Its use as liver support has more basis in contexts of documented dysfunction than as a general preventive measure.

Choline and other digestive cofactors

• Choline plays a role in liver lipid metabolism and cell membrane function, according to the NIH fact sheets.

Note of caution: The evidence on botanical combinations in digestion and liver support is less robust than that of isolated nutrients. Talking about "cleansing" or "detox" without specifying mechanism and context is a simplification that the literature does not support. The value of a formula like Re-equilibrio interno lies in the reasoned selection of standardized ingredients and in tolerability, not in promises of organic cleansing. For more context on digestive ingredients, the article Supplements to improve digestion from the SANA blog develops the physiological approach in detail.

Energy and mitochondrial function: B vitamins, adaptogens, and cofactors without empty promises

Energy formulas are the territory where marketing most easily overcomes evidence. "Cellular energy," "vitality," and "performance" are terms that can be supported by real physiological mechanisms or simply be aspirational. The difference is in how they are formulated and how they are presented.

How to evaluate an energy formula with scientific criteria

• B vitamins: They have well-described functions in energy metabolism, neurotransmitter synthesis, and fatigue reduction. The NIH ODS documents their role in the Krebs cycle and the electron transport chain for vitamins such as B1, B2, B3, B5, B6, and B12. Supplementation makes real sense when there is insufficient intake, increased demand (chronic stress, intense physical activity), or specific contexts such as pregnancy.

• Adaptogens (ashwagandha, rhodiola, etc.): The evidence varies significantly depending on the ingredient. Ashwagandha has human trials showing signals of reduced cortisol and perceived stress. Rhodiola has reviews on cognitive fatigue. But sample sizes are frequently small and the outcomes are subjective. Biological plausibility exists; clinical consistency is more limited.

• Mitochondrial cofactors (CoQ10, L-carnitine, etc.): They have well-established metabolic roles, although the evidence for their supplementation in people without documented deficiencies is weaker.

• Formula coherence: A good energy formulation, such as Energy by SANA, should show that the ingredients make sense together, that the doses are consistent with the literature, and that ingredients are not mixed without a clear physiological justification.

What science does not say: that an energy formula eliminates chronic fatigue, compensates for insufficient sleep, or improves performance in a guaranteed way for anyone.

Prenatal 360: where clinical guidelines rule

Prenatal supplementation is the area where independent evidence is the strongest, most consistent, and most directly applicable. Guidelines from organizations such as NICE, the NIH, or the CDC leave no room for ambiguity regarding priority nutrients: the debate is not whether to supplement, but with what forms and at what doses.

The following table summarizes the key nutrients in prenatal, their function, the level of evidence, and what to check on the label of any formula:

Nutrient	Main function	Level of evidence	What to check on the label
Folate	Neural tube closure, DNA synthesis	Very high (CDC, NIH, NICE guidelines)	5-MTHF or L-methylfolate (active form, does not require enzymatic conversion)
Iron	Hemoglobin formation, anemia prevention	High (NIH: 27 mg/day during pregnancy)	Iron bisglycinate (better tolerance than conventional ferrous salts)
Vitamin D3	Calcium homeostasis, fetal bone development	High (NICE recommends it for all pregnant women)	Dose of at least 400-600 IU; plant-based D3 preferable
Choline	Fetal brain development, DNA methylation	High (NIH: 450 mg/day during pregnancy)	Choline L-bitartrate; absent in most generic prenatals
Iodine	Maternal thyroid function and fetal neurological development	High (WHO and European guidelines)	Potassium iodide in an adequate dose
Vitamin B12	Folate metabolism, neurological function	Moderate-high	Methylcobalamin (active form)

Why active forms matter in prenatal

Folate is the clearest example. Synthetic folic acid requires enzymatic conversion to become the usable form (5-MTHF). In women with genetic variants in the MTHFR gene, that conversion can be less efficient. 5-MTHF, such as Quatrefolic® used in Prenatal 360, does not depend on that conversion because it is already in the directly active form.

The same applies to iron: iron bisglycinate has a better-documented absorption profile and digestive tolerance than ferrous sulfate, especially relevant in a context where nausea is already frequent.

For a more detailed read on how to evaluate a prenatal with clinical judgment, the article How to choose a quality prenatal supplement from the SANA blog develops these criteria in greater depth.

Collagen + vitamin C: what can be supported and what not to exaggerate

Hydrolyzed collagen is one of the ingredients with the greatest presence in beauty supplements and one of those that generates the most disproportionate expectations. The available evidence allows for reasoned claims, but also forces us to be precise about its limits.

	Strongest evidence	Most uncertain evidence
Hydrolyzed collagen (peptides)	Modest but consistent improvements in skin hydration and elasticity in 8-12 week trials	Direct effects on hair and nails; the absorption pathway and tissue redistribution are not fully characterized
Vitamin C	Essential cofactor in endogenous collagen synthesis; well documented by the NIH ODS	Additional benefit of supplementation when there is no prior deficiency
Collagen + vitamin C combination	Biological coherence: vitamin C facilitates the hydroxylation of proline and lysine in collagen synthesis	Few combined studies; most evaluate each component separately

What this means in practice

The combination of hydrolyzed type I marine collagen with vitamin C, as in Beauty: hair and nails, has physiological coherence and clinical signals in the skin. The effects on hair and nails are plausible by mechanism, but the direct evidence is more limited and depends on multiple individual factors.

Presenting this formula as "support for structure and synthesis" is honest. Presenting it as a guaranteed transformation is not. For more context on collagen in women, the article Collagen and vitamin C for women from the SANA blog expands the perspective.

What science does not promise

Recognizing the limits of evidence does not weaken a scientific argument: it reinforces it. Any claim about supplementation that ignores individual variability and the physiological context is, at best, incomplete.

These are the limits to keep in mind when interpreting any study or recommendation about supplements:

1. Evidence about an ingredient does not guarantee the same result in all people. The individual response depends on the baseline nutritional status, genetics, diet, adherence, and physiological stage.

2. The dose matters. An ingredient studied at 400 mg/day does not necessarily produce the same effects at 50 mg/day. Subclinical doses are frequent in low-cost formulas.

3. The chemical form matters. Two supplements with the same ingredient name can have radically different bioavailabilities depending on the salt or ester used.

4. The duration of the study matters. Many trials last 8-12 weeks. Long-term effects are not always characterized.

5. A well-constructed formulation does not replace a balanced diet or the judgment of a healthcare professional. Supplementation is physiological support, not medical treatment. In case of persistent symptoms or clinical doubts, professional consultation is always the first step.

How SANA works with evidence

The methodological framework described in this article is not just a way of reading studies: it is also the criterion with which SANA selects and formulates each product. The difference between a brand that invokes "science" as a sales argument and one that works with real evidence is in the verifiable details.

Formulation criteria that can be contrasted

• Active and bioavailable forms: magnesium bisglycinate, citrate, and acetyl taurate instead of oxide; folate as 5-MTHF (Quatrefolic®); iron as bisglycinate; vitamin B12 as methylcobalamin; vitamin D3 from a plant source (lichen). Each choice responds to literature on absorption and utilization.

• Doses consistent with the literature: the amounts used align with those studied in trials or with the recommendations of organizations such as the NIH, EFSA, or reference clinical guidelines.

• Absence of unnecessary excipients: no colorants, synthetic flavors, or fillers without functional justification. That reduces noise in the formula and improves tolerability.

• Transparency about ingredients: the SANA ingredients page details each component with its function and selection criterion, so that the reader can contrast, not just trust.

• Continuous review: editorial content and formulations are updated when new relevant studies appear or reference recommendations change.

Trust in a supplement should not stem from a slogan. It should stem from being able to trace each ingredient, its form, its dose, and its context back to independent and verifiable sources.

That is the standard SANA aspires to and the one this article has tried to apply transparently. If you want to explore the ingredients of each formula with that criterion, the starting point is the ingredients page or any of the products mentioned: Triple Magnesium, Vitamin D3 + K2, Internal Rebalancing, Energy, Prenatal 360, and Beauty: hair and nails.