FAT CHAT (PART ONE): The fat debate rages on

By Malibongwe Tyilo, DM, 17 May 2021

 Picture: Amirali Mirhashemian/Unsplash

From high fat to low fat and back to high fat, it seems the dietary recommendations from nutritionists and government bodies are always changing. In our three-part series, Maverick Life cuts through the fat to get to the facts.

“The emphasis on limiting total fat intake, as opposed to just saturated fat intake, has been questioned recently by some, but not by others. It is important to remember that humans do not always make food choices based solely on health considerations, but also based on spendable income, occupation, education, ethnicity, rural-urban residence, religious beliefs, nutrition knowledge, and physiologic characteristics. It is likely that the debate about what the optimal fat and fatty acid intakes are to promote health and longevity will continue well into the next century,” wrote multi-award winning US Professor Alice H Lichtenstein in her 1999 article, Dietary Fat: A History.

Her speciality is nutrition and heart disease, and a year after the article was published, in 2000, she served on the US’s Dietary Guidelines Advisory Committee, and in 2015 she was vice-chair of that committee. Indeed, as per the professor’s prediction, the dietary fat debate rages on; a reminder that the field of nutrition is one of ongoing research, open to tweaking and updates as experts reach new findings.

Lichtenstein’s reference to the influence of socioeconomic conditions such as income, occupation, and rural vs urban residence are issues that have also come into play as experts advise governments on nutritional guidelines. Simply put, such guidelines must take into consideration what society actually has access to; so while relatively expensive oils such as avocado oil, olive oil, or flaxseed oil might be considered superior sources of dietary fat, these products might not be accessible to all. 

This is particularly significant when it comes to one of the three macronutrients that are crucial to human health: dietary fat, which, along with the rising popularity of low carbohydrate diets, is once again a key conversation. Some proponents of one of the most popular low-carb diets, the ketogenic diet, recommend that fat should make up as much as 70% of one’s diet. Meanwhile, the latest dietary recommendations from the World Health Organization are that “total fat should not exceed 30% of total energy intake to avoid unhealthy weight gain. Intake of saturated fats should be less than 10% of total energy intake and trans-fats to less than 1% of total energy intake, with a shift in fat consumption away from saturated fats and trans-fats to unsaturated fats, and towards the elimination of industrial trans fats.”

In brief, those saturated fats that are recommended as only a tenth of one’s diet come from animal products such as beef, pork, dairy, butter, cheese, as well as processed foods such as pizza, cookies and bacon. Unsaturated fats come from avocados, some nuts and vegetable oils.

Then there’s the infamous trans fats; although they occur naturally in some meats and in milk, they are considered particularly hazardous to health in their artificial form – also known as industrial trans fats – such as when hydrogen is added to vegetable oil so that it is solid at room temperature. These are the kinds you’re likely to find in junk foods, baked goods and microwave popcorn, to name a few. More about these later when we take a deep dive into the pool of known dietary fats in part two of our FAT CHAT.

While the World Health Organization remains specific on the percentage of total dietary fat intake, increasingly, some countries are choosing a less specific route for their dietary fat recommendations. The Dietary Guideline for Americans 2020-2025, simply states that “for those 2 years and older, intake of saturated fat should be limited to less than 10 percent of calories per day by replacing them with unsaturated fats, particularly polyunsaturated fats”. There is no percentage allocated for total fat intake.

The UK’s Eatwell Guide focuses on recommending a low-fat approach to diet, with no more than a daily intake of 30g and 20g of saturated fat for men and women respectively. Similarly, the Chinese guideline recommends less fat and fried foods, but only specifies a numerical value to trans fats: “For trans fatty acids, the daily intake should be less than 2g.” Even less prescriptive, the South African Food-Based Dietary Guidelines (FBDG) simply recommends: “Use fats sparingly. Choose vegetable oils, rather than hard fats.”

While that might sound low on detail, it is indicative of the shift Lichtenstein spoke of in her 1999 article when she said that “the emphasis on limiting total fat intake, as opposed to just saturated fat intake, has been questioned recently by some…”, as well as the reality of what the majority of South Africans are able to afford. 

In a 2013 paper to explain the decision behind the South African FBDG recommendation of dietary fat, the authors explain that in their research, South Africans have diverse dietary approaches, defined by economic conditions, access to malls, as well as whether they live in urban or rural areas. And even within that dietary diversity the majority consumed well within the recommended 30% limit of total fat intake. In fact, part of the problem, especially in poorer rural areas, was that the consumption of fat was too low.

One of the numerous studies quoted in the paper, strictly looking at black South Africans “aged 35-65 years from the North West province, it was also found that the percentage of energy from total fat was low in the rural areas: 17.6% and 22.6% of energy for men, and 20.3% and 24.1% of energy for women, in the 2005 and 2010 surveys respectively. In the urban areas, it was 25.3% and 26.2% of energy for men, and 28.3% and 27% of energy for women, in the 2005 and 2010 surveys respectively. [The study] demonstrated how total fat intake increased from 21% to 30% of energy in urban African women in South Africa, and from 15.5% to 21% of energy in rural African women from 1975-1996 to 2005. An increased intake of energy from total fat was observed in the urban areas, with figures approaching or already at the upper dietary goal. However, in 2005, the percentage of energy from total fat was still low, at 21% of energy in the rural areas.”

Yet, this does not mean that South Africans are healthier or might suffer from less dietary fat-related medical conditions, because the kind of fat one consumes matters, and a substantial portion of the South African diet is composed of fast foods, be it burgers, pizzas, or a quarter of a loaf of white bread stuffed with slap chips and a slice of polony. Hence, in line with recent global findings, the authors of the FBDG found that the key to appropriate dietary recommendations was to focus on the sources and kinds of fats rather than total intake, while also considering what kinds of food people might have access to.

Key to understanding these recommendations, as well as the variations from country to country, is what is known not only about the difference between saturated and unsaturated, but also the different sub-categories of both those categories, from trans fats to monounsaturated, through to polyunsaturated fats. In addition, while most of the recommendations seem to agree that saturated fats should be kept to 10%, especially as research links them to cardiovascular disease and coronary heart disease, an increasing body of research is starting to suggest that the link is not as strong as previously thought, with some coming to the conclusion that “there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of coronary heart disease or cardiovascular disease”.

In part 2 of FAT CHAT, we speak to medical professionals and nutrition experts to cut through the fat and translate the numbers to the plate. What does 1% of trans fatty acids look like? What does 10% saturated fat look like? Why are some researchers starting to question that limit? We also ask them to differentiate between the saturated, the unsaturated, the mono-, the poly-, and the trans-, to bring you the latest information and what it all really means for your daily meal plan, as well as weekly and monthly grocery shopping. DM/ML