Why Are Nutrition Studies So Confusing?

Several issues make it hard to separate the different ways that nutrition may help keep cancer from spreading.

1. We all eat! We are looking at shades of grey in the amount and types of nutrients in foods.

2. Because of differences in the genetics of each person, we may handle foods differently. For example, these differences can affect how well we handle blood sugar, or how we detoxify and limit damage to DNA and repair any DNA damage that does happen. Other research tries to limit this variabilty by using the same strain of mice, or bacteria.

3. It can be difficult to separate the benefits of choosing a good diet from other lifestyle choices that often go together, for example choosing to exercise regularly.

4. Humans aren’t easy to study. Unlike animal studies, people are studied in a free-living environment and don’t always provide the most accurate records of what they are eating. Since cancer develops from a series of changes in our DNA, and humans live much longer than animals, studies are often too short to get see the benefit or harm from any particular food being studied. 

   “Be open-minded, but not so open-minded that your brains fall out”  Groucho Marx

COMPARE RISK VS BENEFIT

• What are the possible benefits of making a change?

• Does the way it is supposed to work make sense?

• How strong is the evidence?

IN VITRO < IN VIVO < HUMAN STUDIES

In vitro means in glass, which petri plates were originally made of. It can also be called cell culture. Researchers add different nutrients to cancer cells growing in the petri plate and see if there is any change in the growth. That gives us an indication that it might be helpful, but it must then be studied in animals since the interactions within a living creature is much more complicated.

• For example, we don’t yet know if the nutrient will be absorbed in the GI tract, or be able to directly contact a cancer cell.

In vivo means in life, where the nutrient is studied as part of the diet of animals, typically mice or rats, but this varies. Animal studies are important since they have shorter life spans and the impact can be seen far more quickly than studies with humans, and potentially dangerous side effects can be identified.

• Since humans are definitely different than animals, researchers try to use animals with similar issues as humans, for example studying ovarian cancer in chickens. We still can’t assume humans will have the same response, but ideally human studies will follow.

Human studies are the gold standard but complicated for many reasons.

• Since the human lifespan is longer, these are large scale studies over decades, requiring the researchers to follow up with volunteers on a regular basis. Losing contact with some of the initial group means it is harder to interpret the results.

• These studies are extremely expensive to run and hard to fund.  Unlike a drug company studying a drug that may eventually offer a profit, there is less incentive to invest in studying nutrients from foods that can’t be patented.

• Humans want to be good subjects and may report eating “better” than they are. Their diet isn’t being carefully measured and controlled in ways animal studies can be.

• Study participants are randomized, meaning volunteers are assigned to be given the intervention (for example, omega 3 from fish oil) or a “control” meaning a similar looking capsule that doesn’t have the omega 3 in it. The consent for the study talks about what the research is hoping to find, and not wanting to be left out, some people will pick up omega 3 at the health food store to be sure they are getting the intervention. This makes it hard to compare the groups, which now aren’t as different as they were supposed to be. Most current research will also look at blood levels to try to determine the actual difference between the groups.

Are there any risks to you from making a specific change?

• Physical risk

• This is always the main concern of your medical team and of the researchers. It is the reason we first study any intervention at a low dose. If there are no side effects, the intervention can then be given at higher dose, stopping the dose escalation when there are too many side effects to justify the change. Once a safe dose is identified in this Phase 1 study, we can expand it to a larger group of volunteers, looking for the benefit it may offer (Phase 2)

• Financial costs

• For example, does the cost of the change involve more than your budget can handle?

• Time or effort Does it take a significant commitment of time or effort to make the change

• For example, does the new diet plan mean that you are cooking 5 hours a day to have appropriate meals available? Is that something you are willing and able to do?

Since we usually have either more money and less time, or more time but less money, this is a very personal choice. Your medical team will be most concerned about any physical risks involved in choices you are thinking of adding to your treatment plan. They may be able to review the pros and cons of a change and warn you about any physical risk that may be involved, or any potential interactions it may have with other treatments or medications.

Even then, their job is only to educate you about your choices, and you are free to make the final decision.