Carrots are high in vitamin A and beta carotene, hence their name, and are important for the eyes and the immune system. Most of them do not know more about these vital substances – and this statement is sometimes even incorrect.

Vitamin A, provitamin A and beta carotene – what are they?

Because vitamin A is a complex of vitamins that includes retinol and retinyl esters . These forms are mainly found in animal foods.

There is also provitamin A as a precursor, which is found in plant-based foods. “There are also various representatives of provitamin A, the best known is beta carotene,” explains Andrea Henze, nutritionist at the University of Potsdam. The body has to convert provitamin A such as beta carotene into vitamin A so that it can be used. This processing takes place mainly in the intestines and liver.

Beta carotene – like all provitamins A – in turn belongs to the large group of carotenoids, of which there are more than 600 different ones. All of them have the property, as a natural coloring agent, of coloring plants yellow, orange, red and are therefore found in many orange-red vegetables. “But green vegetables such as spinach can also contain a lot of carotenoids,” adds the scientist, who is also researching the subject of vitamin A. In green vegetables, however, the orange-red color of the carotenoids is masked by the green plant substance chlorophyll.

The function of vitamin A.

Vitamin A is vital. “We need vitamin A for almost all body functions because it enables cells to differentiate,” explains Andrea Henze. This means that under the influence of this vital substance, the cell can become a skin cell, a mucous membrane or nerve cell. The other functions of vitamin A:

• Immune system: Vitamin A primarily promotes the development of lymphocytes and thus a strong immune response to foreign substances and pathogens.
• Skin and mucous membranes: It ensures healthy cell growth and cell integrity, thus preventing cracks and other damage, improving wound healing, i.e. regenerating. In this sense, vitamin A also acts on the lung epithelium and supports the constant renewal of the fine cilia that line the lung surface. It is similar in the intestine with the intestinal epithelium. Vitamin A is responsible for this constant renewal.
• Blood formation: Vitamin A promotes the formation of red blood cells (erythrocytes) and thus improves the transport of oxygen into every cell.
• Bones: It influences the storage of calcium phosphate in the bones.
• Reproduction and fertility: Vitamin A is extremely important for the formation of healthy egg cells and sperm as well as for embryonic development. “We know from studies that vitamin A deficiency in animals often causes infertility or, if fertilization does take place, the offspring can have deformities of the limbs,” adds the scientist.
• Seeing: Vitamin A is important in the eye as a pigment that enables the process of vision. It plays a key role in the nerve impulse that is triggered by the incidence of light and sent to the brain. Vitamin A, so to speak, mediates this signal cascade during the visual process.

Vitamin A does not have an antioxidant effect

From a purely chemical point of view, vitamin A is an antioxidant, but it does not play a role in the body in this context, for example because of its binding to transport proteins and its intracellular localization. As is often assumed, it is not a radical catcher and does not protect against “cell rust”, i.e. oxidation. “Vitamin A has no direct effect in this context, only an indirect one,” explains Andrea Henze more precisely: Vitamin A increases the absorption of vitamin E and selenium in the intestine, which have an antioxidant effect.

Pro-vitamins A such as beta carotene, on the other hand, can develop an antioxidant effect in the body before they are converted into vitamin A.

Why is this distinction important? Andrea Henze explains why it is best to use both animal and vegetable sources of vitamin A: Only then can the full spectrum of activity of these vital substances be used to the full.

Foods that are high in vitamin A and beta carotene

Among the foods of animal origin, the following are particularly rich in vitamin A:

• Beef liver
• Pork liver
• poultry
• butter
• cheese
• Eggs

When it comes to plant-based fruits and vegetables, these are good provitamin A suppliers:

• Carrots
• Cabbage
• spinach
• Apricots
• paprika

Store and prepare foods rich in vitamin A correctly

Vitamin A is sensitive to light, so food should be stored in the dark. In addition, the vital substance is relatively heat-stable and fat-soluble. This means that it is bound to fat and can therefore best be absorbed by the body.

In the case of animal sources, this is usually given or due to the preparation, for example the extremely low-fat liver is fried in oil. For the preliminary stage vitamin A, however, the corresponding vegetables should be prepared together with fat. “Studies have shown that it is particularly well absorbed by the body when it is crushed and steamed with a little fat,” reports Andrea Henze. Grinding is important so that the provitamin is released from the cellular structures.

An example: carrot vegetables, chopped up and steamed with a little safflower oil, provide the body with the vitamin better than nibbling raw carrots.

This is how much vitamin A you need every day

According to the reference value of the German Nutrition Society, the daily requirement for vitamin A is around one milligram per day. However, this is a bit simplified. Other units are used in nutritional science, the requirement is given as so-called retinol equivalents (RE) or retinol activity equivalents (RAE), explains the scientist and explains in more detail. 1 milligram of retinol corresponds to 1 milligram of RE or RAE. For provitamin A carotenoids, the calculation is more complex because additional factors have to be taken into account:

• Efficiency of absorption in the intestine (this is generally lower for carotenoids than for retinol or retinyl ester and depends on the food matrix)
• Conversion efficiency of provitamin A into vitamin A (this differs greatly between the provitamin A carotenoids, it is highest for beta carotene)

When using RAE, a conversion factor of 12: 1 is assumed for beta carotene and 24: 1 for all other provitamin A carotenoids. This means that 12 milligrams of beta carotene or 24 milligrams of other provitamin A carotenoids must be ingested with food to meet the requirement of 1 milligram of RAE. If, on the other hand, the intake takes place in the form of retinol or retinyl esters (i.e. from animal foods), the required intake is correspondingly lower.

According to this calculation, the daily requirement for vitamin A is covered with 150 grams of carrots, for example, or with a mixed diet: 1 egg, 100 grams of Gouda cheese and 75 grams of carrots.

Vitamin A deficiency affects certain risk groups

Because these foods are so rich in vitamin A, there is virtually no deficiency in this vital substance in Germany and other industrialized nations. However, that’s only true at first glance. Because experts differentiate between primary deficiency and secondary causes when it comes to undersupply.

Primary means that too few foods rich in vitamin A are eaten. This is almost never the case in this country. Even those who only eat fast food are adequately supplied with vitamin A. Vegans and vegetarians also get enough vitamin A from the preliminary stage.

It is different, however, with a secondary deficiency. In this context, secondary is used when the deficiency arises as a result of illnesses. Digestive diseases that affect absorption, such as:

• inflammatory bowel disease such as Crohn’s disease
• Celiac disease
• chronic liver disease, because vitamin A can then no longer be stored
• Diseases of the pancreas, because the digestive enzymes that are important for the absorption of the vitamin are not sufficiently produced.

In addition, there is a risk of undersupply if the vitamin A requirement is increased, this is the case with:

• pronounced inflammatory processes
• massive injuries such as burns when much of the skin surface is destroyed
• Kidney disease, which causes vitamin A to be excreted in the urine without being used
• Alcohol abuse because liver function is impaired
• pregnancy

Vitamin A Deficiency: Symptoms can be dramatic

As a rule, these risk groups are well looked after by a doctor, so that symptoms of deficiency rarely occur. Exception: alcoholics and very overweight people with massive fatty liver who do not seek medical advice. Apart from these patients, little is known about vitamin A deficiency in Germany. “Vitamin A deficiency occurs mainly in developing countries, where it is the main cause of blindness,” adds the scientist. Because one of the signs of vitamin A deficiency is night blindness, which can increase to complete blindness and is then no longer treatable.

There are also many other causes of night blindness, which are primarily age-related. The adaptive ability of the eye declines, for example as a result of cataracts, macular degeneration or retinopathia pigmentosa (hereditary disease). In any case, a doctor should always clarify if twilight vision deteriorates.

The other signs are a bit unspecific

• Susceptibility to infection
• dry skin and eyes
• brittle hair
• Loss of appetite
• Muscle weakness
• Fertility disorders

Vitamin A deficiency is best compensated for naturally

Anyone who thinks they are undersupplied with vitamin A should simply use more of the corresponding fruits and vegetables. Overdosing is not possible because the body only converts as much provitamin as it needs and it still makes sense to store it.

Over-the-counter supplements are the next step. It is best to get advice from a doctor and trust products from Germany. “Over-the-counter products only contain provitamin A, so overdosing is difficult, and absorption in the intestine is reduced if there is sufficient quantity,” explains Andrea Henze in more detail.

Beware of vitamin A supplements

Vitamin A supplements, on the other hand, can be more problematic, and poisoning is possible if overdosed. In Germany such products are therefore not freely available, but in other countries they are. “Vitamin A supplements should only be used under medical supervision and not for self-medication,” warns Andrea Henze.

Vitamin A poisoning – the first signs

The excess supply of vitamin A does not slow down the body, as is usually the case with provitamin A. The excess vitamin A is mainly stored in the liver; if it becomes too much, the detoxification organ can no longer work. “It leads to intoxication,” says the scientist. In pregnant women, this can also have negative consequences for the embryo.

The signs of vitamin A hypervitaminosis:

• Nausea and headache ,
• the bone tissue becomes porous.

If the oversupply lasts longer, it can even lead to death.

Incidentally, high doses of vitamin A supplements also led to the increase in lung cancer among smokers, previous studies warn.

There is no risk of intoxication from vitamin A through food – with one exception

What is certain is that over-the-counter supplements, which mainly contain beta-carotene, are usually harmless even if taken regularly. It is different with products that contain vitamin A, such as retinol. With them, intoxication is quite possible and can occur with a daily intake of 3 milligrams or more. By the way, retinol can also be found in many care products to keep the skin young and firm. “In this context, there is no need to fear overdosing, the substance does not pass from the skin into the bloodstream,” reassures the expert.

And hypervitaminosis A is hardly to be feared with food either. “Unless you eat liver several times a week,” warns Andrea Henze. Liver can contain over 30 milligrams per 100 grams of goods and thus exceeds the daily requirement by more than 30 times!

A historical anecdote shows how tragic this can end: More than 100 years ago, three researchers set out on an Antarctic expedition, Douglas Mawson, Belgrave Ninnis and Xavier Mertz. The expedition was not a lucky star, the men had to gradually eat the sled dogs in their distress in order not to starve to death. Mertz is said to have eaten the livers as well, subsequently complained of stomach pain, and his skin was partially peeling. After he fell into delirium, he passed away. Experts suspect that it was vitamin A poisoning from the dogs’ liver .

Therefore do not demonize the liver

Nobody knows for sure whether the story is really true. However, it is scientifically proven that hypervitaminosis A from natural foods is not to be feared, unless one eats a liver daily. Apart from that, the liver is an extremely valuable food from a nutritional point of view, contains vitamin A, iron, zinc , copper, vitamin B12 and folic acid, the supply of which is sometimes critical.

The most sensible recommendation: A lack of vitamin A can best be prevented with a balanced mixed diet, i.e. eat a lot of fruit and vegetables, whole grain and low-fat dairy products, sometimes a little fish or poultry.

It can be the cream you put on your face every morning, the beloved hamburger or a habit at the wheel – behind some everyday behavior lurks a danger that hardly anyone knows: you increase the risk of developing cancer. You should therefore leave the following things in the future:

1. Choose your window seat on the plane

Most people enjoy seeing the landscape from above during take-off and landing. Air travelers also like to look at the clouds of cotton wool under the clear blue sky. But if you fly often and sit by the window, you risk skin damage. The window panes keep out most of the UVB rays that cause sunburn. But they let through 47 percent of UVA rays. They are responsible for skin aging and a risk of skin cancer . Because: UV radiation can damage the genetic material. If damaged cells do not die, skin cancer can develop.

2. Insert all receipts

The receipts on thermal paper come from many cash registers and payment devices. And: bisphenol A (BPA). The substance has been classified by the EU as “of very high concern”. It endangers the brain development of the unborn, has been linked to male infertility, and can cause heart disease and cancer. Every time you touch thermal paper, BPA enters the body through the skin and accumulates there. In 2020, an EU-wide ban on thermal paper containing BPA will come into force.

3. Consume very hot drinks

Many people love their soup or tea steaming hot. But whoever swallows liquids above 65 degrees Celsius is putting his esophagus at risk . Because this irritates the tissue and in the long term cell damage occurs, from which cancer can develop.

4. Drive through the rush hour traffic with the window open

As long as there are no clean cars or driving bans in cities, diesel exhaust poses a specific risk for lung and bladder cancer. The WHO investigated this several years ago . Professional drivers or road construction workers are particularly at risk. But you can also get rid of dangerous diesel residues on daily trips through rush hour traffic with stop-and-go movement.

5. Avoid using condoms during sex

Those who live in a monogamous relationship will no longer be infected with the cancer-causing human papilloma virus. Because the greatest risk of HPV infection is unprotected intercourse with changing partners. The most common type of HPV cancer is cervical cancer, which usually develops many years after first exposure to the virus. Infection with certain HPV types can also lead to malignant tumors in the vagina, labia, anus and penis.

6. Use cosmetics with mineral oils

Oils care for the skin, but they shouldn’t be mineral oils. However, these are found in many cosmetic products, from skin cream to lipstick – for example when the ingredients are paraffin, petrolatum or mineral oil. The group of aromatic hydrocarbons (MOAH) poses a health risk. They have the potential to change the genetic makeup and cause cancer. They are filtered out of cosmetics – a decent residue remains, as the testers from the Stiftung Warentester found back in 2015.

7. Drink an after-work beer – or two, three …

Those who drink alcohol not only have an increased risk of liver cancer, but also of mouth and throat cancer and breast cancer. Unsurprisingly, this risk increases with the amount of alcohol. But there is no “safe” lower limit, especially for breast and liver cancer. Various substances that are produced when alcohol is broken down in the body probably play a role here.

8. Staring at your smartphone at night

Studies have shown a link between low levels of melatonin and a higher risk of cancer.The release of the sleep hormone is hindered when light breaks through the nighttime darkness . Smartphones and tablets are a common source of the bright glow in the dark bedroom nowadays. They delay falling asleep or wake the user with incoming messages that are immediately responded to. The sleep cycle is constantly interrupted and chronic sleep disorders develop – a risk factor for cancer.

If you don’t see a doctor, you won’t get cancer because of it. The regular check-ups and preventive appointments with the doctor but can ensure that a tumor early discovered no fatal cancer. The colonoscopy and cervical smear can even prevent abnormal cells from becoming cancer in the first place.

The trace element iron is indispensable for a number of vital metabolic functions in the body. As a component of hemoglobin in the red blood cells, it supplies every body cell with oxygen. Iron deficiency, which manifests itself in anemia, exhaustion, susceptibility to infection, affects around 20 percent of women and ten percent of men in Germany. The higher risk for women is explained by menstruation and decreases accordingly when the childbearing phase of life is over.

Many people have an excess of iron – and know nothing about it

Iron deficiency is known and many nutrition-conscious people pay attention to adequate iron intake. However, significantly more people could have anything but an iron deficiency, namely too much of this trace element. Probably very few people know about it, although it carries a high risk of disease.

Heme iron and non-heme iron: these are the differences

First and foremost, it is important for these relationships – there are the two known, different forms of iron, only one of which can be hazardous to health:

1. Heme iron , i.e. bivalent iron (Fe), mainly found in red meat and sausage. Heme iron has a high bioavailability, the body can use at least 20 percent from food.

2. Non-heme iron , trivalent iron (Fe3), from plant-based nutrient suppliers such as legumes, whole grains, nuts, oil seeds and various types of vegetables. Non-heme iron must first be oxidized to some form of Fe in the small intestine in order for the body to use it. In this way, only around five percent of the iron from food comes into play.

The iron requirement per day is 15 milligrams for women and 10 milligrams for men.

Underestimated health risk heme iron

What is certain is that most people in industrialized nations have at least a sufficient supply of the trace element. Due to our meat and sausage-heavy diet, a large part is even oversupplied with heme iron, and thus risks diseases. Various studies indicate these relationships .

“We assume that too much heme iron can have negative health consequences through eating meat,” explains Matthias Riedl, board member of the Association of German Nutritionists (BDEM) and diabetologist, nutritionist, internist, managing director and medical director at Medicum Hamburg.

The human organism is not prepared for high meat consumption

Normally, a complex mechanism of substances in the liver and intestines controls the iron level. If too much iron storage protein ferritin is measured, the body slows down absorption. “This does not work adequately with large amounts of heme iron, the body continues to absorb it, simply because this form of iron is extremely easy to use,” says the expert.

The nutritionist explains that the cause lies in our evolutionary history. Up until two million years ago, humans were purely plant-eaters, only then did they add animal consumption. That was sometimes more, mostly less meat – definitely a lot less than is regularly eaten today. The human organism is not prepared for this.

High consumption of heme iron feeds cancer cells

The excess iron is then deposited in the pancreas, liver and spleen, which can put stress on the organs. But that’s not all. “Heme iron can promote mutations via certain chemical compounds – for example in intestinal cells, but also in other cells,” warns the internist.

In addition, these compounds have a cytotoxic effect, so they can not only change cells, but also damage them. “And cancer cells, on the other hand, are properly fed by heme iron, so to speak,” says the expert. Malignant cells have a high demand for this trace element. A high consumption of heme iron means that existing cancer cells grow better and are stronger against the immune system.

Meat lovers are more likely to develop diabetes and arteriosclerosis

In addition to the connection between heme iron and cancer, many nutritional studies have shown two other negative effects of the “meat iron”:

1. Numerous studies show that people who consume a lot of sausage and meat are particularly likely to have type 2 diabetes .

2. In addition, this dietary preference often leads to arteriosclerosis , with the well-known secondary diseases of high blood pressure, heart attack and stroke.

“If people don’t eat ‘appropriately’, they get sick”

The higher the meat consumption, the higher the risks for cancer, diabetes and arteriosclerosis. What actually stands behind it: “If people do not eat ‘species-appropriate’, i.e. eat too much red meat and sausage and thus too much heme iron, they will get sick,” warns Matthias Riedl. It is well known that primitive peoples who still eat originally – eat very little meat and no sausage – do not have arteriosclerosis at all, for example.

Trivalent iron from plants is converted into bivalent iron

So heme iron has a rather negative effect on the body. Non-heme iron, on the other hand, does not pose these health risks – but is converted into bivalent iron in the body in order to make it available. Doesn’t it then become as unfavorable as bivalent heme iron? “No, because the trivalent iron from plants is converted into a bivalent iron, but not into heme iron,” explains the expert.

Providing the body with healthy iron – vegetables and fruits with non-heme iron

In order to provide the body with sufficient iron without meat, there are a number of plant-based foods that have a high content of non-heme iron, such as:

• Lentils around 2.7mg / 100gr
• Chickpeas around 2.7mg / 100gr
• Peas 1,5mg / 100gr
• Spinach 3,6mg / 100gr
• Chanterelles 6.5mg / 100gr
• Elderberry 1.6mg / 100gr
• Pine nuts 9.2mg / 100gr
• Millet 6.9mg / 100gr
• Flaxseed, ground 8,4mg / 100gr
• Amaranth 8.9mg / 100gr

Spinach contains a comparatively high amount of iron for a plant-based food, but at the same time the substances it contains can prevent it from being absorbed by the body. Beans or lentils are therefore better suited as a vegetarian source of iron.

Intelligently upgrade the bioavailability of iron from vegetables and fruits

Sure, none of these foods provide as much iron as meat. “The availability of iron from plant-based foods can be increased by cleverly combining the ingredients in a meal,” says Matthias Riedl. Vitamin C, for example, improves absorption. Suggestion for a corresponding daily plan:

• In the morning: oatmeal / muesli with fruit, a glass of orange or lemon juice for breakfast,
• Lunch: millet salad with paprika (the pods are extremely rich in vitamin C),
• In the evening: whole wheat pasta with broccoli or parsley pesto

Coffee and tea inhibit iron availability

However, there are also plant substances that have an inhibiting effect on iron absorption. These are phytates and polyphenols, for example, these plant substances are contained in coffee and tea. So avoid these drinks during, immediately before and after a meal containing iron. In wholemeal products, on the other hand, the phytate content plays a lesser role, as they convince with their high iron content.

Cover your iron requirement healthily, certain meats are also allowed

“Those who follow a purely vegetarian / vegan diet can still get too little iron, especially women are at risk here,” says the expert.

Pregnant and breastfeeding women in particular should take preparations if they have a proven iron deficiency. Otherwise there is a ‘species-appropriate’ solution for everyone: That means a small, moderate meat meal per week, preferably poultry meat, because white meat is not statistically associated with the disease risks mentioned.