Microbiome Diet ~ 2. Animal Products
What impact do fat and animal products have on your internal microbial ecosystem? Our knowledge comes from literature and science, but how can we translate these concepts into real actions and shopping habits?
This is part 2 of the articles on the Microbiome Diet. Read part 1 here: Microbiome Diet 1: Fiber and part 3 here: Microbiome Diet 3: Boost the Beneficial Microbes .
Omega-3 fatty acids
The amount of fat in the diet and the quality of the fat affect the composition of the gut microbiome . To understand how fats differ, we need to look at the chemistry.
Fat molecules are essentially carbon atoms linked together. Depending on the number of hydrogen atoms per carbon atom, dietary fat molecules can be divided into:
- saturated (SFAs)
- monounsaturated (MUFAs)
- and polyunsaturated fatty acids (PUFAs).
PUFAs are also called "essential fatty acids" because they cannot be produced in the body. They must therefore be consumed through the diet. Omega-3 fatty acids are a well-known example of PUFAs.
Although research is still in its early stages, there appears to be a strong link between omega-3 fatty acids, anti-inflammatory effects, and immune response. Supplementation with omega-3 PUFAs has shown positive effects in various conditions, such as cardiovascular disease, rheumatoid arthritis, inflammatory bowel disease (IBD), depression, and cancer .
Omega-3 PUFAs, which are found primarily in fatty fish, have been shown to increase the production of anti-inflammatory compounds, such as the short-chain fatty acid (SCFA) butyrate. SCFAs modulate intestinal immune tolerance and help maintain a healthy gut microbiota. They contribute to a healthy composition of the microbiome and may thus reduce gut symptoms.
Trimethylamine N-oxide
We couldn’t write this blog post without talking about Trimethylamine N-oxide (TMAO). Specific microbes are able to convert dietary choline, betaine, and L-carnitine into trimethylamine, which our liver then converts into TMAO, which is excreted in our urine.
Several scientific studies have found a strong correlation between high TMAO levels in the blood and the risk of serious cardiovascular diseases, such as stroke and myocardial infarction.
A major source of choline and L-carnitine in the diet is red meat, but eggs, shellfish and other meat products are also rich in these compounds. The microbiome, especially in a diet containing animal foods, thus plays a significant role in the risk of cardiovascular disease.
So how can we reduce the production of TMAO while increasing our intake of PUFAs?
1. Fish
Fish is a well-known source of omega-3 fatty acids. However, it is also a source of TMAO and is often contaminated with heavy metals, mainly in the form of methylmercury . If you like fish, a good rule of thumb is no more than 3 servings of oily fish per week .
However, an intake of PUFAs can also be achieved by eating vegetarian and vegan sources of omega-3 fatty acids, such as:
- Seaweed and algae
- Chia seeds
- Hemp seeds
- Flaxseed
- Walnuts
- Edamame beans
- Kidney beans
-
Soybean oil
2. Meat
The consumption of animal products is associated with negative effects on the gut microbiome and, as mentioned, an increase in TMAO. Animal products such as meat and eggs also often contain high amounts of saturated fat, which in itself is a risk for cardiovascular disease.
Additionally, studies show a link between an increase in meat consumption, overall fat intake, and overgrowth of species that normally live in the upper gastrointestinal tract . This type of abnormal colonization is seen in several intestinal conditions, such as IBD, colon cancer, and cirrhosis, as well as in people with arthritis and multiple sclerosis.
Therefore, we recommend reducing the consumption of animal products to a minimum. We recommend that if you eat meat, vary between different animal products, such as white meat, red meat and eggs. In total, we recommend 2-4 servings of animal products per week and a maximum of 1-2 servings of red meat.
3. Dairy products
Whether the fat content of dairy products (e.g. full fat vs. low fat) influences the gut microbiome remains unclear . The majority of current dietary advice still focuses on low-fat dairy products. However, this is not fully supported by the existing literature, and further research is needed to better understand the broader impact of dairy fat on the organisms inside you.
But dairy products like milk, yogurt, and kefir not only contain a variety of nutrients, but also probiotic bacteria that have been shown to modulate the gut microbiome, for example by increasing the abundance of Lactobacillus and Bifidobacterium. Some studies even indicate that yogurt consumption may be protective against pathogenic bacterial strains like Bacteroides fragilis and Salmonella typhi.
We recommend moderate consumption of dairy products, with the aim of adding diversity to your diet. Two servings daily of unsweetened fermented milk products, such as plain yogurt or cheese, is our current recommendation.
Conclusion
The quality and quantity of dietary fat influences the composition of your gut microbiome. Omega-3 PUFAs in particular contribute to the production of beneficial anti-inflammatory compounds.
Some types of dairy products may benefit the body in ways independent of their fat content. For example, consuming milk, yogurt, and kefir may likely increase Lactobacillus and Bifidobacterium, which are associated with improved gut health.
Animal products such as meat and eggs often contain high amounts of saturated fat, which is a risk factor for cardiovascular disease. In addition, animal product intake is associated with negative effects on the gut microbiome and increased blood levels of TMAO.
Therefore, we recommend that you base your diet on plant-based products and reduce your intake of animal products to a minimum.
Author: Cecilia Clausen (Clinical Dietitian)
