Understanding Conjugated Linoleic Acid (CLA)
Conjugated linoleic acid, or CLA, is a type of polyunsaturated omega-6 fatty acid. While many trans fats produced industrially are known to be harmful, the naturally occurring CLA found in dairy and meat from ruminant animals is considered beneficial. The primary natural isomer is cis-9, trans-11 CLA, also known as rumenic acid.
How CLA Gets into Yogurt
The journey of CLA to your yogurt starts in the rumen, the first stomach of ruminant animals like cows and sheep. Here, microbes convert linoleic acid from the grasses and forages the animal eats into CLA through a process called biohydrogenation. This CLA is then absorbed into the animal's body and becomes part of its fat, including the milk fat. When this milk is used to produce yogurt, the CLA is carried over. In some cases, the fermentation process involving specific bacterial starter cultures (like certain Lactobacillus and Bifidobacterium strains) can actually increase the CLA content of the yogurt, making it potentially even richer in CLA than the milk it was made from.
Factors Influencing CLA Content in Yogurt
The amount of CLA in yogurt is not static; it varies significantly based on several factors:
- Fat Content: Since CLA is stored in milk fat, yogurts made from higher-fat milk will naturally contain more CLA. A low-fat or fat-free yogurt will have a drastically lower CLA concentration than a full-fat version.
- Animal Diet: The single most important factor is the diet of the dairy animal. Cows that graze on fresh pasture and grass produce milk with a significantly higher CLA concentration than those fed a grain-based diet. Studies have shown that pasture-fed cows can have milk with 300–500% more CLA.
- Season: The seasonal availability of fresh grass can influence CLA levels. Milk and yogurt produced during the summer months, when cows are grazing on pasture, tend to have higher CLA levels than in the winter when they are fed conserved forage.
- Bacterial Cultures: The type of starter culture used in fermentation plays a role. Certain strains of bacteria have a greater capacity to convert linoleic acid into CLA during the fermentation process, which can further enrich the yogurt.
CLA Content in Yogurt: A Comparison
To understand how yogurt compares to other CLA sources, consider the following table based on fat content expressed as milligrams of CLA per gram of fat (mg/g fat):
| Food Source | Total CLA (mg/g fat) | Notes |
|---|---|---|
| Plain Yogurt (Full-Fat) | $\approx$ 4.8 | Standard CLA content. |
| Lamb | $\approx$ 5.6 | Highest concentration in ruminant meat. |
| Butter | $\approx$ 6.0 | Another high-fat dairy source. |
| Mozzarella Cheese | $\approx$ 4.9 | Ripened cheeses can be good sources. |
| Plain Yogurt (Low-Fat) | Considerably lower | Low fat means less CLA. |
| Beef (Ground) | $\approx$ 4.3 | Levels vary based on diet. |
| Chicken | $\approx$ 0.9 | Lower levels compared to ruminants. |
Potential Health Benefits of Dietary CLA
While research on CLA is ongoing and much has been conducted in animal models, the natural CLA from food sources is associated with several health benefits. The main isomer, cis-9, trans-11, has been most studied for its effects.
- Anti-cancer properties: In laboratory animals, CLA has shown potent anti-carcinogenic effects against certain cancers, including breast, colon, and prostate. Observational studies in humans have also found associations between higher dairy CLA intake and lower risk of certain cancers, though more research is needed.
- Immune system support: CLA has been shown to have immunomodulatory effects, helping to support a healthy immune response.
- Improved body composition: Animal studies suggest CLA can reduce body fat and increase lean muscle mass. However, results in humans have been modest and inconsistent, particularly with supplements.
- Heart health: Some evidence suggests that CLA, particularly from the milk of pasture-grazed cows, might offer a protective effect against heart disease, potentially offsetting the effects of saturated fat in dairy.
It is important to note that the natural CLA found in foods differs chemically from the CLA typically used in dietary supplements, which can have different isomers and effects.
How to Maximize CLA Intake from Yogurt
To get the most natural CLA from your yogurt, consider these tips:
- Choose full-fat: Opt for plain, full-fat or whole-milk yogurt over low-fat or fat-free versions. The CLA is found in the fat content.
- Look for grass-fed: Seek out products from grass-fed cows. These yogurts have significantly higher CLA content due to the animal's diet.
- Opt for organic/pastured: Organic and pasture-raised dairy products are more likely to come from animals with a diet high in fresh grass, which enhances CLA production.
- Buy plain: Flavored yogurts often contain added sugars and ingredients that dilute the nutritional value. Sticking with plain yogurt ensures you get the purest product.
Conclusion
Yes, yogurt is a natural dietary source of conjugated linoleic acid (CLA), with the concentration heavily dependent on the fat content and the diet of the dairy animal. Choosing full-fat yogurt from grass-fed cows is the most effective way to maximize your intake of this beneficial fatty acid from this food source. While the potential health benefits shown in studies warrant further investigation, incorporating high-quality, full-fat dairy like grass-fed yogurt into a balanced diet can be a delicious way to naturally consume CLA, along with other essential nutrients. Remember that the CLA from natural food sources is distinct from synthetic supplements, and a wholesome diet is always the best approach. For more information on yogurt nutrition, refer to resources like Healthline's detailed guide.
