Study Finds 2 Nutrients May Influence Cancer Growth
Scientists start to find out how a person’s microbiome and diet create an environment that helps cancer grow or makes it harder to spread.
Previous research suggests that the ketogenic diet and calorie restriction appear to dampen tumor growth by lowering blood glucose and insulin levels, as both diets are very low in sugar. But new research suggests that sugar isn’t the only nutrient that can predict tumor growth.
“When we compared tumor growth in a mouse model, we got different effects with different diets, even though they were both low in glucose, which meant that another factor had to be at play,” author Principal Matthew Vander Heiden, director of the Koch Institute for Integrative Cancer research at MIT, tells Reverse.
In a study published Wednesday in the journal Nature, Vander Heiden and his team compared the growth of pancreatic tumors in mice fed a keto diet to those given a low-calorie diet.
They found that pancreatic tumor growth slowed in mice after low calorie diet, but not in mice on a keto diet. They attributed this to an imbalance of saturated and unsaturated fat caused by a low fat, low sugar diet.
Essentially, the low-calorie diet seemed to remove the building blocks of cancer cells.
What you need to know first – In humans, calorie restriction involves consuming fewer calories than what is normally consumed, without depriving your body of essential nutrients.
Animal studies and a few human trials suggest that this diet may improve health, extend longevity, and reduce the effects of disease. It is believed to happen because calorie restriction influences processes related to inflammation and sugar metabolism, among others.
The keto diet involves eating meals that are high in fat, moderate in protein, and low in carbohydrates. In humans, it is associated with rapid weight loss, but it is not known what its long-term health effects are. Because it’s high in saturated fat, doctors warn that it can have unwanted effects like heart disease.
When scientists study how these diets influence mice, they put them on the mouse versions of the diet. Keto usually involves eating a type of food broken down primarily into fat, protein, and a few carbs. Mice on a reduced calorie diet have access to food in limited time windows.
Why the discovery was made – It all comes down to the raw materials that cells need to replicate.
Cells have a membrane that separates their internal workings from the external environment. In order for these membranes to function properly, they must be made up of both saturated and unsaturated fat.
“… the kinds of fat you eat in your diet is important because it influences the amount of fat your body is responsible for producing.
But in a low-calorie diet, less fat is available to the body’s cells, so your body has to create saturated fat – the only kind it can create – and then ofsaturates some of that. This supplies the body with saturated and unsaturated fat, which cells need to duplicate themselves.
“It’s a bizarre mammalian metabolism that we produce fat and then desaturate that fat later,” says Vander Heiden. “This creates a situation where the types of fat you eat in your diet are important because it influences how much fat your body is responsible for making.”
The human body performs this desaturation process using an enzyme called stearoyl-CoA desaturase. The enzyme inserts a double bond into saturated fat molecules to create unsaturated fat. Diets low in sugar impair the ability of the enzyme to do so.
But if you follow a high fat ketogenic diet, you end up getting enough fat from your diet to compensate for the sluggishness of the enzyme. The enzyme doesn’t need to work as hard because your body doesn’t have to create so much of its own fat – cancer cells already have everything they need to duplicate themselves.
“… the diet could make our therapies better Where worse. “
With a diet low in sugar and fat, the slow enzyme cannot keep up with desaturation, resulting in an imbalance between unsaturated and saturated fat. This imbalance seems to prevent tumors from growing.
“But if you are on a keto diet, you end up with enough fat that it doesn’t matter because you are saving the effects,” says Vander Heiden.
He and his team saw this unfold in their mice. When the mice followed the mouse version of a keto diet, the fatty acids in their blood increased. During this time, a low calorie diet reduced almost all fatty acids.
Scientists believe that when glucose intake is low – that is, if your diet keeps your blood sugar low because you eat a very small amount of sugars, including carbohydrates and lactose – this difference in fat seems to determine how many resources tumor cells must reproduce.
This is why researchers believe that the low fat and sugar nature of a low calorie diet slowed tumor growth, unlike the keto diet.
Why is this important – Almost 10 million people die of cancer each year. The prognosis is often grim for some types, including pancreatic cancer, which doesn’t cause symptoms until the cancer has already spread. Understanding how to better manage tumor growth is essential to advancing cancer treatment.
“We are not going to cure cancer with food alone, but there are many reasons to believe that diet has an effect on cancer growth,” says Vander Heiden. “And it’s important to think about it because diet could improve or worsen our therapies.”
A diet that suppresses tumor growth in some people could break down a barrier that therapies must compete with when trying to slow or stop the spread of cancer. It could also lead to new treatments.
“The first thing we learned from this research is that if we can understand the mechanism of how diet can affect cancer, we can look at therapeutic approaches that might take advantage of these changes,” says Vander Heiden.
And after – Vander Heiden says what scientists find in mouse models should never be directly applied to humans. Instead, early research like this is the first step that can inform further research in humans.
In other words, we cannot say for sure that a low calorie diet definitely goes slow tumor growth in humans. But it’s a promising step that now needs to be tested in clinical trials. Vander Heiden explains that a better understanding of the mechanisms behind the process, such as those obtained through this study, is essential to moving forward.
“There are a lot of people giving advice on this topic, which is why we decided to study it,” he says. “People make decisions on bad data and if we can get better information, we can design clinical trials that can give patients data-driven advice. Hopefully this will be the first step in this process. “
Abstract: Dietary interventions can alter the levels of metabolites in the tumor microenvironment, which could then affect the metabolism of cancer cells to alter tumor growth. Although calorie restriction (CR) and a ketogenic diet (KD) are often considered to limit tumor progression by lowering blood glucose and insulin levels, we have found that only CR inhibits the growth of allografts. selected tumor growths in mice, suggesting that other mechanisms contribute to tumor growth inhibition. A change in nutrient availability seen with CR, but not with KD, is a decrease in plasma and tumor lipid levels. Upregulation of stearoyl-CoA desaturase (SCD), which synthesizes monounsaturated fatty acids, is necessary for cancer cells to proliferate in a lipid-depleted environment, and CR also alters tumor SCD activity to cause imbalance between unsaturated and saturated fatty acids to slow tumor growth. Enhancing the expression of SCD in cancer cells or increasing circulating lipid levels through a higher fat CR diet confers resistance to the effects of CR. In contrast, although KD also impairs tumor SCD activity, increases in lipid availability induced by KD maintain unsaturated to saturated fatty acid ratios in tumors, and altering the composition of KD fats to increase levels of fat. Tumor saturated fatty acid levels cooperate with decreased tumor SCD activity to slow tumor growth. These data suggest that diet-induced mismatches between tumor fatty acid desaturation activity and the availability of specific fatty acid species determine whether low glycemic index diets adversely affect tumor growth.