September 3, 2024 – You probably already know that a weight loss program wealthy in fruits, vegetables, and other plant-based foods is healthier for you than one which consists primarily of meat and dairy. But until now, dietary research has been unable to elucidate the precise effects of certain varieties of dietary fat on health.
A new study investigated how the consumption of vegetable fats in comparison with animal fats affects lifespan. The researchers found what we already suspected: a weight loss program with more fruit, vegetables, grains and vegetable oils offers higher protection against every type of death and against diseases of the guts and blood vessels (cardiovascular diseases).
And the quantity you eat matters too. People who ate more plant-based fats had a 9% lower risk of death from all causes and a 14% lower risk of death from heart problems than those that ate significantly less of those foods.
On the opposite hand, individuals who ate loads of animal fat, including fat in meat, dairy products and eggs, had the next risk of death from all causes and of death from heart problems than those that ate less. A comparison of the heaviest consumers of animal fat with those with the bottom consumption found that the highest group had a 16% higher risk of overall death and a 14% increased risk of heart problems.
Data from a long-term health study
The greater than 400,000 individuals who participated within the study were a part of the National Institutes of Health-AARP Diet and Health Study. In the group used to check dietary fat, there have been barely more men than women, and the common age of the topics was 61 years. They were enrolled within the study in 1995 and followed until 2019.
At enrollment within the study, study participants accomplished a questionnaire that included questions on their dietary habits, broken down by 124 foods and portion sizes. Total fat intake included each plant sources (corresponding to grains, nuts, legumes, and vegetable oils) and animal sources (corresponding to red and white meat, dairy products, and eggs).
During the 24 years of follow-up, 185,111 deaths were recorded, of which 58,526 were attributable to heart problems (45,634 attributable to heart disease and 10,877 attributable to stroke). The researchers linked these deaths to the dietary information within the baseline questionnaire to calculate the diet-related risk of death after making an allowance for a variety of other aspects that will have contributed to the general deaths.
In addition, the authors examined fats in certain food groups to find out their association with mortality risks. On the plant-based side, for instance, they found that higher fat intake from beans and legumes was not related to any risk of death.
Higher consumption of fat from dairy products and eggs was related to an increased risk of all-cause mortality, including heart problems. Consumption of greater amounts of fat from white meat was related to a lower risk. Fat from beef carries the next risk of death. In contrast, higher consumption of fat from fish was not significantly related to a rise in the danger of all-cause mortality or the danger of death from heart problems.
Links to private characteristics
The researchers also investigated whether dietary changes affect the danger of death. The answer? A transparent “yes.”
Replacing just 5% of calories from animal fat, beef, dairy fat or egg fat with the identical amount of vegetable fat was related to a 4 to 24% lower risk of death overall and a 5 to 30% lower risk of death from heart problems, the researchers said.
Another conclusion: replacing vegetable fats with fish and white meat fat doesn’t reduce the danger of death, it was said.
Because of the fatty deposits that may construct up in people's arteries over time, a change in weight loss program can have very different effects on heart health depending on when in life someone makes the change, said Dr. Walter Willett, a professor of epidemiology and nutrition on the Harvard TH Chan School of Public Health. It takes a protracted time for these deposits to vanish, so the earlier you turn to a more plant-based weight loss program, the higher, he said.
Study co-author Demetrius Albanes, MD, senior investigator within the National Cancer Institute's Division of Cancer Epidemiology and Genetics, agreed with Willett. “Cardiovascular plaques probably take a long time to regress,” he said. “So it's better to change your diet earlier and under medical advice and avoid drastic and extreme diets.”
Possible limitations of the study
A significant drawback of the study, Willett said, is that participants within the NIH-AARP study were only asked about their weight loss program within the baseline questionnaire. Some of the study participants undoubtedly modified their diets in the course of the 24-year follow-up, but these changes weren’t included within the study's data on dietary fat. As a result, Willett said, an increasing number of errors crept into the info used for the evaluation, weakening the link between the participants' diets and the deaths of a few of the study group.
“If we use only the baseline survey, we see only a weak signal amidst the random noise,” he said.
Another problem with the study results, Willett said, is that within the Nineties, when participants took part within the study, they began removing trans fats from foods that contained vegetable oils. Banned by the FDA partial hydrogenation of vegetable oil, a style of food processing that creates trans fats, in 2018. Since most plant-based foods are not any longer partially hydrogenated, he said, “this leads to errors because up to 30 to 40% of the vegetable fats [in the baseline diets] are trans fats, and these massively increase the risk of cardiovascular disease, which means that the benefits of vegetable fats are greatly underestimated.”
Although the authors of the study claim to have statistically controlled the decline in trans fats, they did not do a particularly good job of doing so, says Willet, “because the food composition databases did not keep pace with the changes.”
Between these two problems and the problems with the validity of the questionnaire, he said: “The correlations they describe [in the study] leads to an approximately twofold underestimation of the effect of nutrition [on mortality]. When you take all the sources together, they probably underestimate the impact of diet by four times or more.”
Albanes responded that the study's methodology was valid and that most studies of this type “can only capture the dietary data at the beginning.” Any change in diet over the years
“may have somewhat biased our estimates,” but in that case, their estimates of the risks of animal fats “may have been too low.”
“The trans fat problem is real and there are questions about how that would have affected our follow-up and mortality in our population. That continues to be studied because it is a recent development.”
If the study underestimated the influence of increased intake of vegetable or animal fats on the danger of death, this only underlines the importance of the important thing findings, says Albanes.
Nutritional recommendations
Albanes believes the study's data on mortality risks from different food groups are solid enough to make use of in dietary recommendations. Plant-based fat sources he would recommend, along with vegatables and fruits, include fats from grain products (bread, pasta, etc.) and vegetable oils, including olive, canola and corn oil.
Except within the germ, grains don't contain much fat, Willett points out. “Almost all plants have fat to protect their seeds, and that fat is full of antioxidants.”
Albanes agreed. “When we talk about fat from grains, that refers to all the grains that were asked about in the original questionnaire. It varies whether it's whole grain bread with germ added or refined wheat or white bread.” Although the study didn’t break down the results of whole grain bread in comparison with more processed bread, he said whole grain bread is healthier for health.