Fiber as the key to a strong cardiovascular system?

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The importance of a balanced diet for our health is generally recognized, and the intake of dietary fibre is a key aspect of this. Fiber not only contributes to digestive health, but also plays a crucial role in the prevention of cardiovascular disease. A comprehensive meta-analysis summarizing several studies underlines the importance of dietary fiber for a healthy cardiovascular system. In this article, we take a detailed look at how fiber promotes heart health and why it is an essential part of a healthy diet. 

What is dietary fiber? And where do we find it? 

Dietary fibers are indigestible carbohydrates that are mainly found in plant-based foods and play an essential role in a balanced diet. They play a central role in our digestion and intestinal health. We find them in fruit, vegetables, pulses and healthy cereals such as buckwheat. 

Dietary fiber is not broken down by human digestive enzymes and therefore passes through the digestive tract largely unchanged. They provide far fewer calories than proteins, carbohydrates and especially fats. Their ability to bind water increases the amount of stool and positively stimulates intestinal activity. This improves the consistency and volume of the stool, facilitates intestinal transit and can reduce digestive problems such as constipation. Fiber aids digestion, helps maintain healthy intestinal flora and promotes regular bowel function. But that's not all. Dietary fiber also appears to have a positive effect on our body across biological systems. 

Dietary fiber has a positive effect on the cardiovascular system

Researchers at the National University of Health Sciences in the US state of Illinois were able to establish a link between an increased intake of dietary fiber and a reduction in the risk of cardiovascular disease in an analysis of several large reviews. According to the author, dietary fiber influences several factors that are closely linked to heart health: They help to lower cholesterol levels, regulate blood sugar levels and control body weight. These effects contribute to the prevention of coronary heart disease, strokes, type 2 diabetes and obesity, all of which are risk factors for cardiovascular disease. But let's take a closer look!

Dietary fiber lowers cholesterolmirror 

Dietary fiber, especially soluble fiber, has a significant effect on lowering low-density lipoprotein (LDL) cholesterol, which is often referred to as "bad" cholesterol. This effect of dietary fiber is particularly emphasized in the study author's review. 

Soluble fiber, which is found in foods such as oats, apples and legumes, forms a gel-like substance in the digestive tract. This ability is particularly important for regulating cholesterol levels. In the intestine, this gel-like mass binds the cholesterol and bile acids before they can enter the bloodstream. Bile acids, which are necessary for the digestion of fat, are normally formed from cholesterol in the liver. When fiber binds bile acids in the intestines, they are excreted along with the fiber instead of being reabsorbed. This forces the body to use more cholesterol to produce new bile acids, which lowers blood cholesterol levels. In addition, soluble fiber supports the health of the intestinal flora, which in turn is important for cholesterol metabolism. Healthy intestinal flora promotes the formation of short-chain fatty acids, which have a regulating effect on cholesterol levels.

The reduction of LDL cholesterol through dietary fiber is a key factor in reducing the risk of cardiovascular disease. This effect is enhanced when a high-fiber diet is combined with other healthy lifestyle habits, such as reducing the intake of saturated fats and trans fats. This illustrates how a high-fiber diet can make a significant contribution to reducing the risk of cardiovascular disease.

Dietary fiber lowers high blood pressure 

Fiber also plays an important role in regulating blood pressure, a critical factor in cardiovascular health. The review by the Illinois researcher highlights how increased fiber intake can help lower high blood pressure. The mechanism by which dietary fiber affects blood pressure is complex. On the one hand, fiber is thought to play a role through its effects on gut health and the microbiome. A healthy intestinal flora can reduce inflammatory processes in the body, which in turn can have a positive effect on blood pressure. Chronic inflammation can lead to constriction and stiffness of the blood vessels. Inflammatory cytokines, which are signaling molecules of the immune system, can thicken the vessel walls and make them less flexible, which increases resistance in the bloodstream and thus raises blood pressure.

Inflammation can disrupt the function of the endothelium, the inner lining of the blood vessels, resulting in reduced production of nitric oxide. Nitric oxide is essential for the dilation of blood vessels and the regulation of blood pressure. Therefore, impaired endothelial function can lead to an increase in blood pressure.

Inflammation in the body can cause the kidneys to retain more sodium and water instead of excreting them. This retention, the reduced excretion of sodium and water, leads to an increase in the volume of fluid in the bloodstream. More fluid means more blood flowing through your veins. This increases the pressure on the walls of the blood vessels, similar to allowing more water to flow through a garden hose, which increases the pressure in the hose. As a result, the increased amount of fluid in the bloodstream can lead to higher blood pressure.

Finally, inflammation in the body can affect the renin-angiotensin-aldosterone system (RAAS), a key hormonal system that regulates blood pressure. Inflammation activates the RAAS, which releases more hormones that increase blood pressure. These hormones cause the kidneys to excrete less fluid and the blood vessels to constrict, which leads to an increase in blood pressure. Thus, inflammation can indirectly increase the risk of cardiovascular disease, underlining the importance of inflammation control in maintaining healthy blood pressure.

Fiber-rich foods are often also sources of important minerals such as potassium, which plays a key role in regulating blood pressure. Potassium works by balancing the sodium levels in the body and helping to relax the blood vessels. High sodium levels, often caused by excessive salt consumption, can increase blood pressure. Potassium helps to neutralize this effect and relax the blood vessels, leading to a reduction in blood pressure.

Our modern diet, which is often characterized by a relatively high salt intake, frequently leads to increased sodium levels that exceed the evolutionary norm.

These different mechanisms of action show that dietary fiber is an essential part of a diet aimed at regulating blood pressure and can therefore reduce the risk of cardiovascular disease.

Dietary fiber helps with weight loss and healthy weight management

Dietary fiber plays a crucial role in weight management, which in turn is very important for the prevention of cardiovascular disease. One of the main reasons for this is that fiber-rich foods provide a longer-lasting feeling of satiety. Fiber influences blood sugar levels. They help to slow down the release of sugar from food into the bloodstream, which leads to a more stable blood sugar level. Stable blood sugar levels can prevent cravings and overeating, which is important for controlling body weight.

As we already know, fiber also contributes to gut health and can influence the absorption of calories from food. A healthy gut flora, supported by a high-fiber diet, can improve the efficiency with which the body absorbs and utilizes nutrients.

Dietary fiber improves glucose control and insulin sensitivity

A diet high in fiber significantly improves glucose tolerance and is therefore central to the prevention of type 2 diabetes, an important risk factor for cardiovascular disease. This improvement is primarily achieved by the slower absorption of glucose that fiber causes during the digestive process. This leads to a moderate rise in blood sugar levels after eating, which promotes more stable glucose regulation.

This regulation is particularly beneficial for people with insulin resistance, prediabetes or type 2 diabetes, as it helps to reduce glucose peaks after meals and improve insulin sensitivity in the long term. This effect also supports long-term health in healthy people. In addition, a healthy intestinal flora promoted by a high-fiber diet can reduce inflammatory reactions in the body, which in turn can have a positive effect on insulin sensitivity.

Recommendations for your daily fiber intake

The German Nutrition Society (DGE) recommends a daily fiber intake of at least 30 g for adults. This recommendation applies equally to women and men and is based on the concept of fiber density, i.e. the amount of fiber per 1000 kcal. With an average energy intake of 2050 kcal/day, this corresponds to a target fiber density of around 14.6 g/1000 kcal (2).

The recommended daily fiber intake for adults varies depending on the source, but there is general agreement that adults should consume between 25 and 38 grams of fiber per day. This recommendation is based on several studies and official guidelines (2-5).

These recommendations reflect the general recognition of the positive health effects of a high-fiber diet, including improving heart health, regulating blood sugar levels and supporting digestive health.

According to data from the National Nutrition Survey II, the average daily fiber intake in Germany is around 18 grams per day for women and 19 grams per day for men. These values are therefore far below the recommended guideline value of at least 30 grams per day and a health-promoting optimum range. Below are valuable tips on how you can optimize your fibre intake. 

Conclusion

A diet rich in fiber plays a crucial role in the prevention of cardiovascular disease. Fiber helps lower "bad" LDL cholesterol, regulates blood pressure, supports weight management and improves glucose tolerance. To achieve the recommended 30g of fiber daily, whole grains, legumes, fresh fruits and vegetables, and fiber-rich seeds should be included in the diet. This not only contributes to heart health, but also promotes general well-being and the prevention of other diseases.

Practical tips for a high-fiber diet

The following practical tips are helpful for increasing your daily fiber intake:

1. Healthy and high-quality grains such as buckwheat, millet, quinoa and amaranth are not only rich in fiber. In their whole grain version, they contain far more fiber than their refined counterparts, as the germ and bran of the grain are preserved. They can also be used in a wheat- and gluten-free diet.  

2. Legumes such as lentils, beans and chickpeas are also excellent sources of fiber. They can be used in salads, soups and stews to increase the fiber content of meals.

3. Fruit has a high fiber content and is also easy to eat on the go. Apples, pears, oranges (citrus fruits), berries and kiwis etc. are particularly good, as are dried fruits such as dates, figs and plums.

4. Many vegetables contain a lot of natural fiber. For example, Jerusalem artichokes, broccoli, carrots, potatoes, rose and white cabbage. They are also a healthy snack option compared to processed products, which often contain little fiber. 

5. High-fiber seeds such as psyllium husks or chia and flax seeds are particularly rich in fiber and can be easily integrated into yogurts, smoothies and baked goods. 

A sample recipe for your high-fiber breakfast 

Here is a simple and high-fiber recipe for a buckwheat-chia-berry porridge:

You need these ingredients:

• 1/2 cup buckwheat flakes
• 2 tbsp chia seeds
• 1 tbsp psyllium husks
• 1 cup of plant milk of your choice
• 1 cup mixed berries (fresh or frozen)
• 1 banana
• Optional: honey to sweeten
• Optional: nuts and/or coconut flakes for the topping

How do you process all the ingredients for your porridge? 

1. Mix the buckwheat flakes, chia seeds and psyllium husks in a bowl and pour over the plant milk. Either leave to soak overnight in the fridge or prepare at least 10-15 minutes before eating.
2. You can also mix in a hemp or whey protein powder to increase the protein content. As these are often flavored, this also gives them a special touch.
3. If the mixture is too thick after the resting time, you can add a little more plant milk or water.
4. Add berries and a sliced banana and, if desired, sweeten with honey or a plant-based alternative
5. Top your porridge with nuts and coconut flakes
6. Enjoy your high-fiber breakfast!

This recipe is not only rich in fiber, but also offers a good balance of healthy fats, proteins and natural sugars from the berries.

Are you looking for a high-fiber, healthy and wheat-free bread? Then try making tasty buckwheat bread yourself! Here is my favorite recipe: 

Make buckwheat bread yourself!

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Sources: 

1. McRae MP. Dietary Fiber Is Beneficial for the Prevention of Cardiovascular Disease: An Umbrella Review of Meta-analyses. J Chiropr Med. 2017 Dec;16(4):289-299. doi: 10.1016/j.jcm.2017.05.005. Epub 2017 Oct 25. PMID: 29276461; PMCID: PMC5731843.
2. King, D., Mainous, A., & Lambourne, C. (2012). Trends in dietary fiber intake in the United States, 1999-2008. Journal of the Academy of Nutrition and Dietetics, 112 5, 642-8. https://doi.org/10.1016/j.jand.2012.01.019.
3. Anderson, J. (1990). Dietary fiber and human health. Hortscience, 25, 1488-1495. https://doi.org/10.21273/HORTSCI.25.12.1488.
4. Covello, A., Baumgartner, N., Curran, M., Reeser, G., Cohen, N., Kramer, A., Hillman, C., Barbey, A., & Khan, N. (2016). The Sexual Dimorphic Relationship Between Dietary Fiber Intake and Visceral Adipose Tissue. The FASEB Journal, 30. https://doi.org/10.1096/fasebj.30.1_supplement.lb228.
5. Hooper, B., Spiro, A., & Stanner, S. (2015). 30 g of fiber a day: An achievable recommendation? Nutrition Bulletin, 40, 118-129. https://doi.org/10.1111/NBU.12141.
6. https://www.dge.de/wissenschaft/referenzwerte/ballaststoffe/