Studies & science

✍️ How we read studies (so “evidence” really means evidence)

Not all studies carry the same weight. Three simple questions help you judge the quality of what you’re seeing:

⚙️ Chromium: glucose markers & macronutrient metabolism

Chromium has been studied for decades in relation to glucose parameters and broader metabolic markers. The picture is nuanced—and that’s precisely why it’s worth taking seriously rather than turning it into a headline.

🔎 What does the research say?

Meta-analyses on chromium supplementation report, particularly in people with type 2 diabetes, potential improvements in glycaemic markers in some studies—while also noting variability in study quality and outcomes. A frequently cited paper is the meta-analysis by Balk et al. (2007) on PubMed: “Effect of chromium supplementation on glucose metabolism and lipids” (Balk, 2007). More recent syntheses often land on a similar conclusion: possible benefits in some settings, but not consistently across all populations—for example, Asbaghi et al. (2020).

A grounded takeaway is this: if chromium shows an effect, it may be more likely in groups with impaired glucose regulation—not as a universal “metabolic boost” for everyone.

✅ What can be said as an authorised health claim?

For chromium, authorised wording exists along the lines that it:

(As always, the use of any claim depends on meeting the relevant conditions, such as minimum nutrient levels.)

⚡️ B vitamins (B1, B2, B3, B5, B6, B7, B9, B12): energy metabolism & fatigue

B vitamins aren’t a trend ingredient; they’re closer to what you’d find in the engine room. Biochemically, they act as co-factors in central pathways—especially those involved in converting food into usable energy.

🔎 What does the research say?

Here, the evidence base is less about a single blockbuster trial and more about a broad physiological foundation: when B vitamin status is inadequate, energy-related processes can be measurably disrupted. The practical point isn’t “turbo energy”, but a straightforward logic—adequate intake supports normal function. That’s exactly what authorised claims are designed to reflect.

✅ What can be said as an authorised health claim?

Depending on the specific B vitamin, authorised claims include statements such as contributing to:

These are functional, not medical, statements—and they shouldn’t be stretched into disease-related claims.

☘️ Glucomannan: soluble fibre, fullness—and why dose matters

Glucomannan is a soluble fibre (from konjac) that swells markedly in water. That physical property is the centre of many research questions: What happens when a fibre increases volume and may influence gastric emptying?

🔎 What does the research say?

Systematic reviews have assessed glucomannan in the context of body weight and related markers, with mixed outcomes. A well-known meta-analysis is Onakpoya et al. (2014), which takes a critical view of the overall evidence. Another overview is Zalewski et al. (2014).

One theme turns up repeatedly: dose and administration are pivotal. Many trials use gram-level intakes per day and clear instructions (often taken with plenty of water, split across the day). In real-world use, the gap between “on the label” and “in practice” can be large—so generalising results without dose/context is risky.

✅ What can be said as an authorised health claim?

There is an authorised claim for glucomannan in relation to weight loss, but only under specific conditions (notably a minimum daily amount and use with water as part of an energy-restricted diet). That limitation is crucial: below those conditions, the claim cannot be responsibly applied.

⛹‍♂️ L-carnitine (as L-carnitine L-tartrate): metabolism in training and weight-management contexts

Physiologically, L-carnitine plays a role in transporting fatty acids (simplified: a “shuttle” function toward mitochondria). It’s an appealing mechanism on paper—which is exactly why it has been tested so often.

🔎 What does the research say?

Meta-analyses of randomised trials tend to report modest, sometimes statistically significant effects in certain contexts, alongside substantial variation between studies (dose, participant group, duration, and accompanying lifestyle changes differ widely). Examples include:

A sensible conclusion is that L-carnitine isn’t a substitute for energy balance, movement, or diet. But it is an ingredient that has been repeatedly examined in the literature, with results that appear to depend heavily on context.

✅ What can be said as an authorised health claim?

For L-carnitine, there are no generally authorised EU/GB health claims that equate to “fat burning” or “weight loss”. Responsible communication sticks to study descriptions and physiology—without converting that into a promised outcome.

☕️ Green tea extract: catechins (e.g., EGCG), caffeine, and the reality of small effects

Green tea extracts are often studied for catechins (including EGCG) and, depending on the extract, caffeine. Many trials look at them together because thermogenesis and oxidative metabolism are rarely one-lever systems.

🔎 What does the research say?

Meta-analyses have reported small changes in weight-related or weight-maintenance parameters, particularly in studies using catechin–caffeine combinations. A commonly cited overview is Hursel et al. (2009). Mechanistic discussion appears in sources such as Westerterp-Plantenga et al. (2010). A practical nuance that often comes up: habitual caffeine intake may influence responses—which helps explain why results don’t look the same in every group.

⚠️ Safety: more important than the headline

With green tea extracts, safety deserves as much attention as efficacy—especially at higher catechin intakes. EFSA has published a detailed evaluation here: EFSA Scientific Opinion on the safety of green tea catechins (2018). The short version: most studies report no issues, but rare cases of liver injury have been discussed, particularly in relation to certain high-dose extract exposures.

☘️ Raspberry fruit extract: polyphenols, metabolic markers—and a younger human evidence base

Raspberries contain bioactive compounds (including anthocyanins and ellagitannins) that are often studied in relation to post-meal metabolic responses. A key distinction matters here: evidence from whole-food intake does not automatically translate to the same conclusions for extracts.

🔎 What does the research say?

A fair bottom line: the human evidence is promising but less settled, especially when you’re talking about extracts and weight-management outcomes rather than whole-food patterns.

⚛️ Probiotic cultures (Lactobacillus, Bifidobacterium, Streptococcus thermophilus): microbiome science without exaggeration

Microbiome research is moving fast—and it’s also a field where oversimplification is everywhere. The rule of thumb is stronger here than almost anywhere else: strain, dose, duration, and starting point matter.

🔎 What does the research say?

✅ What can be said as an authorised health claim?

With probiotics, the research landscape is broad, but authorised claims are limited. That makes it especially important to treat study results as what they are: findings under study conditions, not blanket promises that apply to every person and every strain.

✅ Conclusion: what you can responsibly take from the evidence

If you want a quick way to separate “hype” from “signal”, this is the practical summary:

✍️ References (selected)