For maximum effectiveness
Economical, for 7-10 months !
To neutralise free radicals
Bone formation and mineralisation
Strengthen immunity and fight viruses
Regulate calcium levels in tissues
Reduce blood pressure
Our Vitamin D3/K2 FORTE food supplement is highly dosed, 5600 IU per capsule, which is the maximum you can find.
The luxury bottle is made of amber glass to protect from light and keep all the properties. 2 years shelf life !
If you are looking for information on the combination of vitamins D3 and K2, read on, it is exciting !
A hitherto underestimated vitamin, menaquinone or K2, seems to be able to reinforce the beneficial effects of vitamin D3. Think it's too good to be true? Read on to find out more about this powerful combination of vitamins !
Table of contents
1. The most important information in brief
- Vitamin D3 or cholecalciferol is a form of vitamin D found in foods of animal origin. It is also synthesised by exposure to sunlight.
- Vitamin K2, so far only recognised as essential for clotting, may prevent arterial calcification and increase the safety of vitamin D3 supplements.
2. What you need to know about combining vitamins D3 and K2
Vitamin D is essential for maintaining bone, heart and brain health. Its most potent form, vitamin D3, stimulates the absorption of calcium from the diet. At the same time, vitamin K2 ensures that the mineral calcium is deposited in the right places (bones and teeth).
3. What is vitamin D3 ?
A vitamin is a molecule essential to the body's well-being, which is needed in small quantities and cannot be synthesised by the body or other compounds, so it must be ingested through a healthy diet. Its name is derived from the combination of the Latin word vita (life) and amine (organic compound).
Vitamin D is a fat-soluble molecule. Although there are up to five types of this vitamin, the human body recognises only two: vitamin D2 or ergocalciferol and vitamin D3 or cholecalciferol. The latter is more potent than ergocalciferol.
Vitamin D2 is found in plant foods and some mushrooms, while consumption of animal products increases the supply of vitamin D3. Surprisingly, exposure to sunlight can also promote the production of cholecalciferol, which is why D3 is known as the 'sunshine vitamin'.
4. Why is vitamin D3 considered superior to vitamin D2 ?
Both cholecalciferol and ergocalciferol are inactive forms of vitamin D. Before they can perform their beneficial functions, both substances must be metabolised by the liver and kidneys to give rise to the active form of this vitamin: calcitriol. Therefore, the difference between D3 and D2 is their origin:
- Vitamin D2 or ergocalciferol is found in some plant foods, such as certain mushrooms, which can produce it after exposure to ultraviolet light from the sun.
- Vitamin D3 or cholecalciferol is found in many animal products, such as oily fish, eggs and dairy products. It is also synthesised by the skin after exposure to UVB radiation from the sun.
However, many studies have shown that vitamin D3 produces a greater conversion to calcitriol than its analogue, vitamin D2, being 60% when it comes to maintaining stable vitamin D levels. This is why cholecalciferol is the preferred form of vitamin D for most nutrition experts.
Unfortunately, vitamin D3 supplements in most cases contain an ingredient of animal origin (usually fish oil). It is therefore becoming very important for vegans and vegetarians to get half an hour of sunlight a day if they want to increase their vitamin D3 stores.
Did you know that the body is able to synthesise vitamin D3 after exposure to the sun? This is why some experts prefer to think of it as a hormone rather than a vitamin.
5. What are the benefits of vitamin D3 ?
Vitamin D3 obtained from food or exposure to sunlight passes into the bloodstream. There it is metabolised by the liver and kidneys into its active form (calcitriol), ready to be used by the body when needed.
Its most important functions and benefits are summarised in the following list :
- Increased intestinal calcium absorption
- Control of phosphorus and calcium levels in the kidneys
- Creating a new bone
- Dental reinforcement
- Replacement of damaged bone tissue
- Development of muscle contraction
- Reduction of blood pressure
- Controlling inflammation
- Strengthen immunity
- Protecting neuronal tissue from ageing
- Mood regulation
- Regulation of hormone production (estrogen and testosterone)
- Appetite control
99% of the vitamin D stored in the body will be used to regulate calcium levels in tissues. The remaining 1% will be used as an essential cofactor in the production of several processes essential to the body's well-being, such as weight regulation or the development of strong muscles.
6. What is vitamin K2 ?
Vitamin K, like vitamin D, is a fat-soluble substance whose absorption is enhanced if ingested in the presence of fat. In 1935, the Danish physician Henrik Dam determined that this molecule was essential for coagulation and named it "vitamin K" after this function (from "Koagulation" in German).
There are currently five variants of this vitamin. Its two natural derivatives are vitamin K1 or phylloquinone (abundant in green leafy vegetables) and vitamin K2 or menaquinone (found in foods of animal origin and fermented products such as cheese or natto, a soy derivative).
Did you know that vitamin K deficiency can cause bleeding in newborns? It is therefore advisable to give babies a preventive injection of this vitamin shortly after birth.
7. What is the difference between vitamin K2 and vitamin K1 ?
Until a few years ago it was thought that the only difference between vitamin K1 and vitamin K2 was their origin, as the body has the ability to easily convert phylloquinone into menaquinone.
However, some experts have begun to suggest that these substances are considered two separate nutrients.
Although both vitamins are essential factors in the activation of proteins that regulate clotting and other equally important metabolic processes in the body, vitamin K2 is associated with a decrease in calcium deposition in blood vessels, which improves vascular health. Vitamin K1 does not have this property.
Several studies have found that older people (especially women) who maintain high levels of vitamin K2 have a lower incidence of osteoporosis and calcification of the arteries, which is not the case with K1 users. This is the main difference between the two molecules.
8. What are the functions of vitamin K2 ?
Vitamin K, in whatever form, acts as a cofactor or molecule involved in blood clotting processes. It also acts as a metabolic regulator and antioxidant with protective effects against various types of cancer (including colon and breast cancer) and dementia.
Vitamin K2, on the other hand, has a number of properties that appear to be unique to this substance. Below is
a table comparing the functions of all forms of vitamin K with the special characteristics of menaquinone.
|Fonctions of vitamin K
||Exclusive functions of vitamin K2
|Activation of coagulation
||Prevention of arterial calcification
||Prevention of cardiac calcification
||Cellular antioxidant for the skin
|Immune response enhancer
||Strengthening of the tooth enamel
|Regulator of energy
|Regulation of hormone production (increase in testosterone in
men and decrease in women)
Vitamin K2 was an understudied nutrient until relatively recently. More evidence is needed before its beneficial effects can be officially confirmed. Nevertheless, the most recent experiments provide very promising data which reinforce the idea that vitamin K2 is an essential nutrient for health.
9. What is the relationship between vitamin D3 and vitamin K2 ?
Vitamin D3 will promote the absorption of calcium and the mineralisation of bones and teeth. However, some experts are concerned that very high levels of vitamin D and calcium may lead to the deposition of this mineral in inappropriate places, such as the walls of blood vessels and the kidneys.
Vitamin K2 also contributes to the mineralisation of bones. At the same time, it will activate a number of proteins that are closely related to calcium in bone and dental tissue. This will increase the amount of minerals deposited in the bone and decrease the concentration of calcium that can impair the function of other organs.
For this reason, many nutrition experts consider these vitamins to be synergistic, meaning that they work together to enhance their beneficial actions. Vitamin K2 will allow vitamin D3 to exert its effects by preventing the undesirable effects associated with excessive supplementation of this substance.
10. What are the recommended dosages for vitamin D3 and vitamin K2 ?
The recommended intake of each nutrient is decided according to scientific criteria and ratified by various international organisations. In the case of vitamins D3 and K2, the recommended daily allowance (RDA) is based on different variables, such as age, gender and the particular health status of each individual.
In the case of vitamin D3, the RDA can be quantified as international units (IU), a parameter that measures the degree of biological activity, in nanograms (ng) or micrograms (μg). The RDA for vitamin K2 will be measured in micrograms. The RDAs for each of these substances are shown in the table below :
||RDA vitamin D3
||RDA vitamin K2
|Baby 0-6 months
||400 UI or 10 μg
|Baby 6-12 months
||400 UI or 10 μg
|Children 1-3 years
||600 UI or 15 μg
|Children 4-8 years
||600 UI or 15 μg
|Teenagers 9-18 years
||600 UI or 15 μg
|Adults up to 70 years
||800 UI or 20 μg
|Women over 70
||800 UI or 20 μg
|Men over 70
||800 UI or 20 μg
11. Which people are affected by vitamin D3 and K2 deficiency ?
Foods rich in vitamin K2 are very rare in the western diet. The body will mainly use vitamin K1, which is much more abundant in our diet. This vitamin will be able to maintain the blood clotting function, but will not provide the same amount of benefit as vitamin K2.
Vitamin D3 deficiency is also very common. It is estimated that between 30% and 80% of the world's population suffers from some form of deficiency of this vitamin, mainly caused by reduced exposure to sunlight, excessive use of sunscreen and the promotion of a sedentary lifestyle.
Some people are much more vulnerable to hypovitaminosis D3 or K2 than the general population. Those listed below should plan their diet carefully to avoid any type of imbalance related to the absorption or accumulation of these vitamins:
- Over 60: the ability to absorb, store and synthesise these vitamins decreases with age.
- People who work nights, office workers and students: Their exposure to sunlight is less than that recommended to keep vitamin D3 levels within healthy limits.
- People with dark skin: skin with more melanin absorbs the sun's rays and hinders the production of vitamin D3.
- Vegans and vegetarians: cholecalciferol and menaquinone are difficult to find in a plant-based diet, increasing the likelihood of deficiencies in these nutrients.
- People who frequently use sunscreen: by blocking ultraviolet rays, the formation of vitamin D3 will be impeded.
- People with chronic intestinal diseases: Absorption of all vitamins (including D3 and K2) will be affected in case of malabsorption (as in ulcerative colitis or Crohn's disease).
- People on frequent antibiotic treatment: the beneficial bacteria in the gut help to absorb vitamin K2. Their destruction will affect the levels of this vitamin.
- People who consume alcohol in excess: this oxidising substance opposes the absorption of vitamin K2 and impairs its functions.
12. What problems can an imbalance between vitamins D3 and K2 cause ?
The effects of vitamin D3 deficiency seem insidious, causing a non-specific feeling of tiredness and discomfort. If this situation is not corrected, problems in the metabolism of calcium and other minerals will occur, leading to osteoporosis, joint pain and bone and muscle damage.
Problems resulting from vitamin K2 deficiency will further affect the body's ability to clot. At the slightest touch, bruising, injury or bleeding occurs (e.g. bleeding gums after brushing teeth). In the case of women, menstruation will become very heavy and will take time to disappear.
On the other hand, if vitamin D3 levels remain high, but vitamin K2 levels fall, the likelihood of dietary or supplementary calcium accumulating in the arteries increases, causing high blood pressure and slowly but insidiously damaging the heart and kidneys.
13. How can I increase my vitamin D3 and K2 levels ?
All experts agree that exposure to the sun is the most effective way to obtain increased levels of vitamin D3. Sunbathing for 15-30 minutes a day will provide sufficient cholecalciferol, although the use of sunscreen may make it difficult to obtain vitamin D3 in this way.
For people who do not want to expose themselves to sunlight, it is possible to obtain this vitamin through diet.
Animal foods such as chicken liver, salmon and egg yolk are particularly rich in vitamin D3. Unfortunately, there are no vegan food sources of this vitamin.
Vitamin K2 is much more difficult to obtain, especially if you follow a 'western' diet (such as the Mediterranean diet). This nutrient is found in small amounts in animal products, such as goose liver or freerange eggs. It will be more abundant in fermented foods such as natto and some cheeses.
14. Which foods are rich in vitamin D3 ?
Large amounts of vitamin D3 are found in foods of animal origin, such as fish, eggs and dairy products. Below is a table showing the main sources of vitamin D3 and their cholecalciferol concentration in relation to the recommended daily allowance or RDA for an adult:
||Approximate concentration (UI)
||% RDA (for an adult)
|Cod liver oil (1 tablespoon)
|Mackerel (75 g)
|Whole milk (250 ml)
|Egg yolk (per unit)
|Veal liver (75 g)
|Margarine (1 teaspoon)
Although the absorption of vitamin D3 from the diet is less efficient than its production through sunlight, a varied diet rich in these products can provide sufficient cholecalciferol for good bone, mental and heart health.
15. Which foods are rich in vitamin K2 ?
The amount of vitamin K2 present in animal products is highly dependent on the feed provided to the animals throughout their lives. Free range eggs, for example, have a higher vitamin K2 content than eggs from caged hens.
Fermented foods, which are rich in phenokinone, must be refrigerated and stored properly to avoid deterioration of the vitamin K2 they contain. The following table contains a list of foods rich in vitamin K2, both animal and fermented:
||Approximate concentration (μg)
||% RDA (for an adult)
|Natto - Fermented soybeans (100g)
|Goose pâté (100g)
|Matured cheeses: Parmesan, Grana Padano (100g)
|Brie cheese (100g)
|Farmhouse egg yolk
|Cage egg yolk
|Chicken breast (100g)
|Veal liver (100g)
|Whole milk (100 ml)
16. Who should take a vitamin D3 and K2 supplement ?
Since a large percentage of the population has inadequate levels of vitamin D3 or vitamin K2, some nutritionists recommend supplementing everyone. Other experts are more reserved and recommend giving an extra dose of these vitamins only to people who belong to one of the following groups:
- Over 60 years old
- Vegans or vegetarians
- People with limited exposure to sunlight
- Postmenopausal women, especially if they suffer from bone loss
- Obese people
- People who have undergone bariatric surgery or bowel resection of any kind
- People with cardiovascular problems (hypertension, heart failure)
- People on a very restrictive or unbalanced diet
- People with renal failure
The combination of vitamin D3 and K2 will be particularly beneficial for people with a family or personal history of cardiac events associated with arterial calcium deposition. In this case, vitamin K2 will act as a protective element to prevent arterial calcium deposition, which may be caused by D3 supplementation.
17. What types of vitamin D3 and K2 supplements are there ?
Vitamin D3 and K2 supplements can be purchased in various formats, such as capsules, drops or powder. The cholecalciferol in these items will in the vast majority of cases come from animal products, although some manufacturers claim to have mushrooms that can produce vegan D3.
In the case of vitamin K2, there are several isoforms (molecular variants) available in dietary supplement form.
The varieties of vitamin K2 most commonly used for supplementation are known as "vitamin K2 MK-4" and "vitamin K2 MK-7". Its actions in the body are summarised below:
- Vitamin K2 MK-4: MK-4 is the most active form of vitamin K2. It is rapidly absorbed and stored in the brain, arteries, pancreas and salivary glands.
- Vitamin K2 MK-7: This form of vitamin K2 penetrates more easily into bone and liver tissue. There, it is metabolised into vitamin K2 MK-4 to generate its beneficial effects.
Experts recommend using a vitamin D3 and K2 supplement that contains a balanced combination of the two menaquinone isoforms. In this way, vitamin K2 can reach all parts of the body equally, protecting bones, arteries, kidneys and brain tissue.
18. How do I take my vitamin D3 and K2 supplement ?
Combined vitamin D3 and K2 supplements should be taken according to the manufacturer's instructions. They are simple to use and usually only one dose per day will be required. In the following paragraphs you will find answers to the most common questions that may arise when using these products:
- In what quantities ? It is advisable to choose a supplement that provides the recommended daily dose of vitamin D3 and K2. In general, the items on sale offer much higher amounts of cholecalciferol and menaquinone than the RDA, so in most cases a single daily dose of the supplement will be sufficient.
- In what proportion ? An adequate amount of vitamin K2 ensures the correct use of vitamin D3 and prevents the hardening of the arteries caused by the correct deposition of calcium. To this end, it is recommended that the chosen supplement contains at least 45 vitamin K2 per 1000 IU of cholecalciferol.
- With or without food ? As vitamin D3 and vitamin K2 are fat-soluble molecules, they are best absorbed during meals, preferably with fatty or seasoned foods. A salad seasoned with olive oil, for example, will facilitate the assimilation of the supplement.
19. What benefits can I expect from my D3 and K2 supplement ?
Maintaining vitamins D3 and K2 within the recommended limits is associated with an overall improvement in physical, mental and metabolic health. These molecules act synergistically, enhancing their beneficial effects and providing a range of benefits that are summarised in the following list:
- Increased muscle performance (strength and endurance)
- Decrease in blood pressure
- Increased bone density with reduced incidence of fractures
- Decreased incidence of heart or coronary heart disease
- Improved blood vessel condition, reduction of varicose veins
- Strengthens tooth enamel and reduces the incidence of caries.
- Increased energy
- Protection against infections (colds, flu and catarrh)
- Mood enhancement
- Preservation of intellectual capacities (especially memory)
- Reduction of LDL-cholesterol (bad cholesterol)
- Better control of bleeding
- Improved skin appearance
- Relief of symptoms of psoriasis and other chronic inflammatory diseases
- Increased speed of healing of bruises
- Regulation of testosterone production in men
- Improvement of polycystic ovary syndrome symptoms in women
- Increased insulin sensitivity, with a reduction in blood sugar levels.
Studies have established a relationship between optimal levels of these vitamins and a lower incidence of cancer. Several studies have been published (on breast cancer, colon cancer and prostate cancer, among others) that offer promising results on the anti-cancer capacity of these substances.
20. Is it possible to overdose on vitamin D3 and K2 ?
Vitamin D3 can be stored in the body's fatty tissues and is difficult to eliminate. Ingestion of too much of this vitamin leads to unpleasant effects such as weakness and vomiting. Fortunately, vitamin K2 works by reducing the intensity of these symptoms.
As we have seen, vitamin K2 is also a fat-soluble substance. Paradoxically, toxic effects secondary to consumption of this substance have not been described, even at very high doses (100 times or more the RDA), so no upper limit of daily intake has been set for menaquinone.
Did you know that the synthetic counterpart of vitamin K, K3, is toxic in high doses and it is therefore very important not to confuse it with vitamin K2 ?
It is therefore advisable not to exceed a daily limit of 5000 IU for vitamin D3. In addition, it is essential to choose a supplement containing 45 μg of phenokinone per 1000 IU of cholecalciferol, thus avoiding the occurrence of side effects. Although there is no established limit for vitamin K2, the RDA should not be exceeded.
21. What side effects can D3 and K2 supplements cause ?
The use of any type of supplement can cause adverse effects of varying severity. The combination of vitamins D3 and K2 can also cause side effects, although these are mostly minor inconveniences without serious clinical consequences.
Common side effects: It is possible that some side effects may appear annoying, but without major transcendence, such as flatulence, abdominal discomfort and a feeling of abdominal bloating. These side effects will gradually disappear as the body gets used to digesting the supplement.
Uncommon side effects: Some unpleasant symptoms have been described with vitamin D3 and K2 supplementation, such as nausea, vomiting and severe abdominal pain. These effects are much less frequent than those described in the previous paragraph, but require dose adjustment or discontinuation of supplementation.
Rare side effects: In exceptional cases, more serious effects may occur, such as intense vomiting and diarrhoea, loss of appetite and muscle weakness. In this case, it is advisable to stop taking the supplement immediately and to go to a medical centre as soon as possible.
22. What are the contraindications of vitamin D3 and K2 supplements ?
Although vitamin D3 and K2 supplements are generally considered safe, they are not without contraindications. People who have difficulty controlling their blood sugar levels should be very careful with this type of supplement, as it can cause an unexpected drop in blood sugar levels.
People with liver or kidney problems have a sensitive metabolism and should consult a trusted health professional before starting supplementation with these vitamins. It is also not recommended that pregnant or breastfeeding women take vitamins without supervision.
Finally, you should be aware of possible drug interactions between these vitamins and known medical treatments. If you usually take any of the medicines listed below, consult your doctor before starting supplementation with these vitamins:
- Warfarin (anticoagulant vitamin K antagonist)
- Treatment of chronic renal failure
- Hypolipidemic drugs (drugs that lower cholesterol) such as Orlistat.
- Medications for the treatment of psoriasis
- Some antibiotics, such as tetracyclines
- Digoxin (anti-arrhythmic treatment)
- Antihypertensive treatment
- Thyroid hormone
- Some diuretics
The combination of vitamin D3 and K2 has exploded into the world of supplementation. These two molecules form an incomparable team that will provide all the benefits of cholecalciferol while limiting its side effects.
Its antioxidant activity makes this supplement an indispensable element.
If you follow our advice, you can get the most out of your D3 and K2 supplement. Smart use of this product will protect both your bones and your cardiovascular system, allowing you to enjoy an active and disease-free life for many years to come. Keep an eye out for this wonderful supplement!
If you enjoyed our guide to vitamins D3 and K2, leave a comment and share this article.