Questions & answers
All frequently asked questions from our articles at a glance — grouped by article, with a link to the full answer.
Vitamin D in winter: needs, intake and sensible amounts
Go to articleHow much vitamin D do you need per day?
If no endogenous synthesis from sunlight occurs, DGE gives an estimated value of 20 µg (800 IU) of vitamin D per day. In summer most of it is produced via UV-B exposure; in winter (October to March) that's barely possible in Germany.
Is 15 minutes of sun in winter enough?
In Germany north of the 50th parallel, the sun stands so low from October to March that UV-B isn't sufficient for vitamin D synthesis — no matter how long you're outside. The body then draws on stored vitamin D from the summer months.
Which foods contain vitamin D?
Fatty fish (salmon, mackerel, herring), egg yolk, some mushrooms (especially those grown under UV light) and fortified foods like margarine. Through food alone, very few people reach the estimated value of 20 µg.
Can you take too much vitamin D?
With consistently high intake from supplements, raised calcium levels can develop. EFSA has set a tolerable upper intake of 100 µg (4,000 IU) per day for adults (set in 2012, currently under EU re-evaluation). When in doubt, stay close to the DGE recommendation.
Magnesium and muscle function: what the research shows
Go to articleHow much magnesium per day makes sense?
DGE recommends 300 mg (women) or 350 mg (men) of magnesium per day for adults — pregnancy and breastfeeding stay at 300 mg as well. Athletes can have a slightly higher need due to losses in sweat. From supplements, BfR recommends a maximum of 250 mg additionally per day.
Which magnesium form is best absorbed?
Comparative studies tend to show better uptake for magnesium citrate and magnesium bisglycinate than for magnesium oxide. In daily life, consistent intake over several weeks usually matters more than the exact compound.
Magnesium and calf cramps — what's established?
Magnesium contributes to normal muscle function. Whether a single cramp is magnesium-related depends on many factors — fluid balance, electrolytes, exertion. For frequent or severe complaints, please talk to your doctor.
Can I take too much magnesium?
From food, practically no. From supplements, the BfR maximum of 250 mg per day applies. Higher amounts can lead to soft stool or diarrhoea.
Iron and tiredness: what to keep an eye on in everyday life
Go to articleIn which life phases is iron intake particularly relevant?
DGE reference values (2023 update): 11 mg for men, 16 mg for women before menopause. They go up in pregnancy (27 mg), during intense endurance training, with heavy menstruation, frequent blood donation and strictly plant-based diets. Breastfeeding people sit at 16 mg.
What's the difference between heme and non-heme iron?
Heme iron is found in animal-source foods (meat, fish) and is absorbed at roughly 15–35 % efficiency. Non-heme iron from plant sources (legumes, whole grains, leafy greens) is absorbed at only 2–20 % — uptake depends heavily on the rest of the meal.
How can I improve iron uptake from plant sources?
Vitamin C with the meal (peppers, citrus fruit, fresh sauerkraut) clearly raises non-heme iron uptake. Coffee, black tea and calcium-rich foods inhibit it — so leave 30–60 minutes between them.
When should I see a doctor?
Persistent unexplained fatigue, pale complexion, brittle nails or concentration problems are reason for a blood test at your GP — including ferritin (iron storage) and haemoglobin. Self-diagnosis or high-dose iron supplements without medical findings can do harm.
Antioxidants and cell protection: what selenium, zinc and vitamin C actually do
Go to articleWhat are antioxidants?
Antioxidants are substances that neutralize free radicals — short-lived, reactive molecules that arise in metabolism and through external influences. In the EU, vitamin C, vitamin E, selenium, zinc, manganese, riboflavin and copper are explicitly allowed to carry the claim of contributing to the protection of cells from oxidative stress (EFSA, Regulation 432/2012).
Who has higher needs?
According to the DGE, smokers need clearly more vitamin C (135 mg women, 155 mg men per day, instead of 95/110 mg). Endurance athletes, people in phases of high physical load, and people in recovery benefit from rich intake of fruit, vegetables and antioxidant trace elements.
Is an antioxidant supplement worthwhile?
As a blanket rule, no. A diet with five portions of fruit and vegetables per day (DGE recommendation, ca. 750–1000 g) covers vitamin C, E and carotenoids well. Selenium and zinc can be tighter depending on diet and soil quality — targeted supplementation can make sense, high-dose multi products do not.
Can you overdose on antioxidants?
Yes. Selenium is toxic in higher doses (selenosis: brittle nails, hair loss — EFSA UL 255 µg/day); zinc above 25 mg/day from supplements can disrupt copper uptake; high-dose beta-carotene has been considered problematic in smokers since the ATBC study (1994). For daily amounts from supplements, refer to the current BfR document.
Are secondary plant compounds antioxidants?
Yes, many act as antioxidants — polyphenols, flavonoids, carotenoids, lycopene. EFSA has not authorized health claims for most of these compounds, though, because evidence from clinical trials for isolated single substances is usually insufficient. When in doubt: the whole food rather than the isolated extract.
Omega-3 for heart function: EPA, DHA and ALA explained
Go to articleHow much omega-3 per day makes sense?
For the heart-function claim, the EFSA threshold is 250 mg of EPA + DHA per day. DGE additionally recommends that around 0.5 % of energy intake be covered by ALA — at 2,000 kcal that's about 1.1 g, at 2,500 kcal about 1.4 g per day.
What's the difference between EPA, DHA and ALA?
ALA is the plant-based omega-3 fatty acid from linseed, rapeseed or walnut oil. EPA and DHA are the long-chain forms, mainly in fatty sea fish and algae. The body converts ALA only to a very limited extent — studies put DHA conversion at around 0.5 %, EPA somewhat higher.
Are algae-oil capsules an alternative to fish oil?
Yes. Algae oil delivers EPA and DHA directly and is animal-free. For vegans or people who eat little fish, it's a sensible option. Check the declared EPA+DHA content per daily dose.
What to check when buying?
Total EPA+DHA per daily dose (at least 250 mg for the heart claim), proof of purity for heavy metals and PCBs, fresh stock with light-tight packaging if possible — omega-3 oxidises easily.
B vitamins at a glance: B12, B6, folate and what they do
Go to articleDo I need all B vitamins as a complex?
A B-complex covers general needs — sensible if you generally eat little animal-source food or suspect higher needs. If you want to close a specific gap (e.g. B12 on a vegan diet), a single-nutrient product is the better choice.
Can B vitamins be overdosed?
Most B vitamins are water-soluble and surplus is excreted. The exception is vitamin B6: long-term intake well above the recommended level has been linked to sensory symptoms. Germany's BfR updated its supplement upper-limit recommendation in 2024 — for daily amounts from supplements, refer to the current BfR document.
Is it enough to eat nutritional yeast regularly?
Nutritional yeast is a good source of B1, B2, B3 and B6. B12 is naturally present only in trace amounts — fortified yeast varieties exist, but you have to check the label. People on a vegan diet should always supplement B12 deliberately.
Does folic acid make sense outside pregnancy?
Yes. Folate contributes to normal blood formation and to amino acid synthesis (EFSA) — that applies in every life phase. When trying to conceive and in early pregnancy it is additionally recommended to supplement 400 µg per day, starting at the latest 4 weeks before conception.
Micronutrients after 50: which gaps actually show up in everyday life
Go to articleWhich micronutrients matter most after 50?
Primarily vitamin B12 (stomach absorption declines), vitamin D (the skin's own synthesis drops noticeably), calcium (bone metabolism), and depending on diet B6, folate, and omega-3. Iron becomes less acute in women after menopause — DGE 2023 lowers the recommendation from 16 mg to 14 mg per day.
Do I automatically need a 50+ multivitamin?
No. The DGE doesn't recommend multivitamin products as a standard solution for older adults either. What makes sense are targeted steps: vitamin D in winter, B12 with confirmed absorption issues or strictly plant-based diet, calcium where a doctor recommends it. „Optimal-Set 50+" products are a marketing category, not a medical standard.
How often should I have blood values checked after 50?
There are no fixed recommendations — taking stock at the next regular checkup makes sense. Standard checks include: hemoglobin, ferritin, vitamin D, B12, thyroid markers. With chronic complaints (fatigue, concentration issues, bone pain), absolutely talk to a doctor before self-supplementing.
How do I notice a B12 deficiency?
Early signs are nonspecific: fatigue, concentration problems, tingling in hands or feet, forgetfulness. That's exactly why B12 deficiency is often noticed late — and especially after 60 the frequency is clearly elevated (atrophic gastritis affects an estimated 10–30 % of those over 60 per DGE). A blood test at your doctor clarifies it in one visit.
What changes for women after menopause?
Iron requirement drops (DGE 2023: 14 mg instead of 16 mg per day), and at the same time bone metabolism becomes more important: calcium and vitamin D gain weight. Hormonal changes can also affect B vitamins and magnesium — there are no blanket answers here, just individual medical guidance.
Skincare from within: which nutrients actually support the skin
Go to articleWhich micronutrients are EFSA-recognized for skin?
For the maintenance of normal skin, the EU explicitly approves: biotin, niacin (B3), riboflavin (B2), vitamin A, zinc and iodine. Vitamin C contributes to normal collagen formation for the normal function of the skin. Other substances — collagen powders, hyaluronic acid, coenzyme Q10 — are eagerly marketed as 'beauty nutrients' but lack corresponding EFSA health claims.
Does collagen powder really help against wrinkles?
EFSA hasn't authorized health claims for collagen powders for skin. Marketing claims about wrinkle reduction or rejuvenating effects from drinkable collagen are legally precarious. What the skin actually needs is enough total protein (see [Amino acids and sport](/en-gb/knowledge/amino-acids-and-sport)) plus the EFSA-recognized micronutrients — not a specific high-priced powder.
Which foods are 'good for the skin'?
Colorful plant foods with vitamin C (peppers, berries, broccoli), whole grains and legumes for B vitamins and zinc, nuts and eggs for biotin, fatty sea fish for vitamin D and omega-3, high-quality vegetable oils for vitamin E. A balanced mix covers skin supply in most cases.
What does the skin show with deficiencies?
Cracked corners of the mouth can indicate iron, zinc or B-vitamin shortfalls. Dry, flaky skin a deficiency of biotin, essential fatty acids or vitamin A. Wound healing problems sometimes indicate zinc or vitamin C deficiency. Important: such symptoms are hints, not diagnoses. With persistent skin problems, the dermatologist or GP is the right address.
How important is drinking water for the skin?
Very important — and at the same time the effect is often overestimated. The DGE recommends about 1.5 liters of water per day from beverages for adults (additional water comes from food). Anyone chronically drinking too little will notice it on the skin too. Anyone already drinking enough won't get better skin from extra liters — the water balance is regulated by the kidney.
Amino acids explained: BCAA, EAA, and protein needs in sport
Go to articleWhat exactly are amino acids?
Amino acids are the building blocks your body uses to assemble proteins. There are 20 proteinogenic amino acids; 9 of them are essential for adults — meaning you have to get them from food because your body can't produce them itself.
What's the difference between BCAA and EAA?
BCAA (branched-chain amino acids) refers to the three branched-chain amino acids leucine, isoleucine and valine. EAA (essential amino acids) covers all 9 essential amino acids — including lysine, methionine, phenylalanine, threonine, tryptophan and histidine. EAA is the more complete group.
How much protein does the DGE recommend?
Adults 19–65: 0.8 g/kg body weight per day. From age 65, the DGE raises this to 1.0 g/kg. Pregnant women in the 2nd trimester +7 g, in the 3rd trimester +21 g; breastfeeding +23 g per day. These are pure dietary requirements — no sports add-ons.
Are amino acid powders worthwhile for athletes?
Not necessarily. People who get enough protein from food (legumes, quark, fish, eggs, meat, whole grains) usually supply the body with all essential amino acids in sufficient quantity. EFSA has not authorized health claims for isolated amino acids or BCAA in a sports context — marketing claims about muscle building via amino acid powders are legally precarious.
What happens with protein deficiency?
With sustained low protein intake, the body loses muscle mass, the immune system is impaired, wound healing slows, and in severe cases water retention occurs. Clinically relevant protein deficiency is rare in Germany — but in older people, those with eating disorders, or certain chronic conditions, it can become a real issue.
Micronutrients — what your body actually needs
Go to articleWhat are micronutrients?
Micronutrients are vitamins, minerals, and trace elements. Unlike macronutrients (protein, fat, carbohydrates), they don't supply energy, but they're necessary for nearly every metabolic process. The body can't make most of them — you have to take them in via food.
Which micronutrients are most often short in Germany?
According to the National Nutrition Survey II, women mainly fall below the DGE estimated value for iron, folate, and vitamin D; for men it's primarily folate and vitamin D. Magnesium and vitamin B12 are relevant on a strictly plant-based diet and in some age groups.
Do I need supplements?
Across the board: no. With a balanced diet, most needs are covered. Supplementation makes sense in targeted cases — vitamin D in winter, B12 on a vegan diet, iron with a diagnosed deficiency. The DGE explicitly does not recommend multivitamin products as a default solution.
Where do I find reliable daily intake values?
From the German Nutrition Society (DGE reference values) — broken out by age, sex, and life stage. The DGE updates these regularly (iron 2023, vitamin B6 2024). For upper limits from supplements, the BfR is the source.
What does bioavailability mean?
Bioavailability describes how much of a nutrient the body actually absorbs and uses from a given source. It depends on chemical form, the meal context, and individual factors. Example: heme iron from meat is absorbed at 15–35%, plant non-heme iron at only 2–20%.
Welcome to the VitalFit Knowledge Hub
Go to articleAre diseases treated here?
No. The knowledge hub provides general information on micronutrients and well-being. For health-related questions please speak with your doctor.
Which sources are used?
We rely exclusively on official sources such as EFSA, DGE, BfR and peer-reviewed studies. Manufacturer websites are not accepted as evidence for effect-related statements.
Bioavailability explained: how much of a nutrient your body actually absorbs
Go to articleWhat does bioavailability mean?
Bioavailability describes how much of a nutrient the body actually absorbs and can use from a given source. That's usually clearly less than what's declared on the package or in the food. Iron from meat is absorbed at 15–35%, plant iron at only 2–20%.
Which factors influence absorption most?
Three areas: the chemical form of the nutrient (e.g., heme vs. non-heme iron, magnesium citrate vs. magnesium oxide), meal context (vitamin C with iron helps, coffee blocks), and individual factors (gastric acid, gut health, age, medications).
Are expensive special forms really better absorbed?
Sometimes yes, often barely. With magnesium, citrate tends to be better than oxide; with iron, heme iron from meat is better than non-heme iron in tablets — but very expensive 'premium forms' rarely deliver dramatically better values in studies than standard formulations. Consistency in everyday life is usually more relevant than the exact compound.
What inhibits absorption of minerals?
Phytates (in whole grains, legumes) bind iron, zinc and calcium. Oxalic acid (spinach, rhubarb) inhibits calcium and iron absorption. Tannins (coffee, black and green tea) block iron uptake. Calcium and iron compete for absorption — so calcium tablets and iron-rich meals should be timed apart.
What promotes absorption?
Vitamin C with non-heme iron — can clearly boost absorption. Some fat with fat-soluble vitamins (A, D, E, K) is necessary for absorption at all. Acid (e.g., lemon juice) and fermentation (sourdough, sauerkraut) help with many minerals.
Vital-Check: How your individual micronutrient evaluation works
Go to articleWhat does the Vital-Check cost?
Nothing. The Vital-Check is a free initial evaluation — no appointment, no sales pitch, no hidden fees.
How long does it take to fill in?
Around three to five minutes. We ask about your daily routine, your diet and your goals — no diagnostics, no medical tests.
What happens to my data?
Your information is stored encrypted and used exclusively to create your individual evaluation. Health-related details are deleted automatically after 6 months. Details are in the privacy policy, section 2a.
Will I be added to a marketing list automatically?
No. After the Vital-Check we contact you once via WhatsApp or email with your individual evaluation — afterwards only if you explicitly want it.