Today, I am going to discuss one reason why full-fat dairy products may be better than low-fat dairy products. I am going to focus on the aspect of sugar content, inflammation, and type 2 diabetes in this post, but will focus on other aspects, such as cardiovascular disease and cancer, in my next posts!
Take a look at these two types of yogurt. The first is full-fat Fage Greek Yogurt and the second is Yoplait Low-fat cherry flavored yogurt. As you can see there are striking differences between the two. The Fage yogurt has 190 calories compared to 170 calories in the Yoplait and 10 grams of fat compared to 1.5 grams. The biggest difference however comes in the sugar content, 8 grams of sugar for the Fage, all of which come from the lactose in the milk, and 26 grams of sugar in the Yoplait, most of which come from the second ingredient listed, sugar. Further the protein content is very different, 18 grams in the Fage compared to only 5 grams in the Yoplait.
A lot of people would choose the Yoplait version because it has less calories, and more importantly, much less fat. In terms of the caloric content, the serving size of the yoplait is only 170 grams compared to 200 grams for the Fage. If we increase the Yoplait serving size to 200 grams, the same serving as the Fage it would actually contain 200 calories! Even at the current serving size, consuming 30 more calories from the Fage product is not a big difference, especially when we consider the high added sugar content of the Yoplait. Many people are fat-phobic today because of recommendations from the government and advertisements for low-fat and fat-free products. The current recommendations are that we consume less than 10% of our calories from saturated fats. This means for the average 2000 calorie diet only 200 calories or 25 grams of saturated fat. Although this recommendation has been made for years, there’s actually no direct link between saturated fats and heart disease. Also, we need fat to survive-- it is important for hormone regulation, absorption of fat-soluble vitamins, and appetite regulation!
As I mentioned in my last blog post, full-fat dairy products may be healthier because they don't contain the added sugar and the extra fat is filling. A study conducted in Australia looked at the level of hunger and fullness at different time points in 16 lean males and 16 obese males after consuming either a high-fat, high-protein, or high-carbohydrate meal at lunch of approximately the same caloric content. The researchers found that at 3 hours those who at either a HF or HP diet had less hunger compared to the high-carbohydrate diet. Further, those who ate the high-fat meal had the most fullness at 3 hours, indicating that the high-fat meal is more satiating in the long-term than the other macronutrient meals. When the researchers looked at the ratings for the obese subjects, the obese subjects eating a high-fat meal felt hungrier than the high-protein meal at 180 minutes, but their fullness rating was the same at 180 minutes. Their increase in hunger when eating a high-fat meal could be because both oral and GI sensitivity to fat is diminished in the obese.
This was the macronutrient breakdown of 1) high-fat [HF; %energy from fat/protein/carbohydrate 55:15:30; protein content (g/kg body wt): 0.4], 2) high-protein (HP; 25:45:30; 1.35), 3) high-carbohydrate (HC; also low-protein LP; 30:10:60; 0.2), or 4) adequate-protein (AP; 30:30:40; 0.8).
There were a few limitations to this study. First, it had a small sample size. There were only four individuals per group (16 total for lean, 16 total for obese). Further, I would have liked to see the effect of these different macronutrient composition meals over a longer period. They only tested satiety levels after consumption of this one meal! These individuals may have had more satiation from a high-fat meal after getting accustomed to it by eating it for 7 days, for example.
But back to my original point! Have you ever tried to eat a fat-free yogurt plain? It tastes awful and I can barely finish it! But a plain full-fat yogurt is creamy and leaves me satisfied. The fat-free yogurt never leaves me satisfied and I find myself having to add toppings, such as nuts. This addition of nuts adds back in all the calories and fat instead of just consuming the full-fat product. Most people may not add the toppings to their yogurt, but they will feel less satisfied from the fat-free dairy product and tend to eat more calories and fat later to make up for it.
The other reason many low-fat or fat-free products are not satiating is because of the high sugar content that is added to make up for the lack of taste. This high added sugar content initially raises blood sugar, but then leads to a big dip in blood sugar levels making us hungry very quickly again. Full-fat dairy is better for appetite regulation. Full-fat yogurt does contain sugar in the form of lactose from the milk, but doesn't contain added sugar for taste. Also the yogurt contains fat so when we eat full-fat yogurt, it slows the rate of digestion.
A study conducted in Sweden used the data from the Malmo Diet and Cancer cohort. It looked at 26,930 individuals aged 45-74 years old and collected dietary data. At fourteen years of follow-up 2860 individuals had type 2 diabetes. The researchers found that intake of high-fat dairy products was inversely associated with developing type 2 diabetes. In other words, those who consumed high-fat dairy were much less likely to develop T2D compared to those who consumed low-fat dairy products.
Interestingly, the biggest inverse associations were seen in individuals who consumed cream and high-fat fermented milk as well as cheese in women. These results may point to the fact that the low- or fat-free dairy products contain higher sugar content, raising blood sugar, and over a prolonged period of consumption, increasing T2D risk.
However, there are some limitations to the study itself and its applicability. The study was conducted in Sweden where cows are not subjected to living in CAFO’s for their whole life. Most cows in Sweden are grass-fed and this will improve the fat composition of the dairy products, increasing the amount of omega-3 fatty acids instead of omega-6 fatty acids. The cohort only includes individuals from Sweden who were born between 1923 and 1950. This may influence the generalizability of the study to Americans because of dietary differences between the countries and the fact that many younger Americans are developing T2D. According to the study, dairy is the most important fat source and contributes 30% of total fat intake and 35% of saturated fat intake in Sweden. In the US, the corresponding figures are 12% and 24%, which is quite different. Since this is a cohort, the researchers relied on a questionnaire describing dietary patterns. These questionnaires always have the possibility of error from over- or under-reporting of certain foods consumed as well as inaccurate portion size reporting. Another problem is that classification of low-fat compared to high-fat products differs between studies. Although there are a few limitations, I think the results are still very interesting in light of the low-fat/fat-free movement.
The added sugar content to fat-free or low-fat yogurts is not only bad for glucose levels and appetite regulation, but also systemic inflammation, which increases risk for cardiovascular disease, cancer, and other chronic diseases. Dairy products contain medium-chain saturated fatty acids, which are different than other fats because they’re more readily metabolized and utilized as energy. A study was conducted assessing the effect of dairy consumption on inflammation in those with metabolic syndrome. Participants were included in the study if they had metabolic syndrome based on the following criteria: abdominal obesity (a waist circumference of 102 cm for men and 88 cm for women), high triglycerides (150 mg/dL), low HDL cholesterol (,40 mg/dL for males and ,50 mg/dL for females), elevated blood pressure (130/85 mm Hg), and high fasting glucose (100 mg/dL). The subjects were then randomly assigned to either a low-dairy diet (<0.5/serving a day) or adequate-dairy diet (3.5 daily servings).
After 12 weeks, the adequate dairy group had decreased malondialdehyde and oxidized LDL. They also had significant reductions in other inflammatory markers, while the low dairy group had no effect on oxidative or inflammatory markers. Although this study doesn’t speak to the distinct macronutrient composition (although it was likely low-fat), it presents information that the consumption of dairy does not increase inflammatory markers, especially in individuals in a high-risk group such as these participants who had metabolic syndrome.
Even if the dairy product consumed does contain less fat, I think it’s still important to make sure there is no added sugar, as this does increase bodily inflammation.
That’s all I’ve got for tonight! Stay tuned for my next post discussing full-fat dairy and heart disease!
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