On Nutrition
This week, I’m answering your questions about carbohydrates and diabetes, lowering cholesterol with diet and lifestyle, and the pros and cons of eating fish.
Do you need to avoid carbs if you have diabetes?
My short answer is no. While plenty of people — some expert, some not — recommend that people with diabetes restrict carbohydrates, the reality is that not all carbs are created equal.
A 2024 research review looked at the effects on diabetes control and cardiovascular health — always a concern since diabetes is a risk factor for cardiovascular disease — from diets both high and low in fiber and carbohydrates. They found that the high-carb, high-fiber diets were better at reducing blood levels of A1C, fasting insulin, total cholesterol and “bad” LDL cholesterol. That’s consistent with previous research showing that high-fiber diets improve risk factors for diabetes and cardiovascular disease and reduce the risk of premature death among people with diabetes.
The average American eats 10 to 15 grams of fiber per day, whereas the official recommendation for adults age 50 or younger is 25 grams for women and 38 grams for men. After age 50, that drops to 21 and 30 grams, respectively. High-fiber carbs include bran cereal and whole grains, beans and lentils, and fruits and vegetables. Low-fiber carbs include added or isolated sugar in all its forms (including honey, agave syrup, date syrup, etc.) and refined white flour and foods made from it.
While I think continuous glucose monitors are overused right now by people who have blood sugar levels in the normal range, for many people with diabetes or prediabetes it may be helpful to use a CGM in conjunction with keeping a food record for a period of time so you can see how food choices — as well as other factors such as physical activity and stress — affect your blood sugar. Ideally, this also involves working with a registered dietitian nutritionist who can help interpret these findings and provide deeper context and understanding.
Is it possible to lower cholesterol on your own and if so, how long should you wait to see results?
Improving your diet and increasing physical activity can both lower total and “bad” LDL cholesterol levels as well as triglyceride levels. Because your cholesterol levels are affected by what you eat over time, any changes to diet and exercise generally take three to six months to have an effect — if they’re going to. Some people find that lifestyle change can really move the needle, while others simply don’t.
Dietwise, you could start by eating less saturated fat by sticking to lean sources of animal protein, increasing fish meals to twice per week, and adding more meatless meals that use, beans, lentils or soy foods for protein. Plant-based protein also includes fiber, which is important. A 2016 Cochrane review found that all types of dietary fiber may reduce total and LDL cholesterol, but notable sources are barley and oats, which are rich in beta-glucan, a type of soluble fiber that reduces the absorption of cholesterol from food. If you’re increasing your fiber, do so gradually and make sure you’re also drinking enough fluids. Whole soy foods like edamame, soy milk, tofu and tempeh may inhibit cholesterol production and increase its excretion from the body. This is due to a variety of compounds, including proteins, isoflavones, phytosterols and beta-glucan.
If your physical activity levels aren’t what they could be, make a plan for gradually, steadily and consistently adding more activity to your day. If your doctor has recommended statins, have a conversation about whether you can take a six-month “watch and wait” approach while you make some of these changes. The answer may also depend on how high your cholesterol levels are, and whether you already have other risk factors for cardiovascular disease.
How do you reconcile the recommendations to eat fish and seafood with the fact that fish may contain mercury, PCBs or other contaminants?
Overwhelming research shows that the benefits of eating fish (the recommendation is for two or three 4-ounce servings of fish per week) outweigh the risks of these potential downsides, but I understand the concern. The reality is that no food is “perfect.” As we’ve unfortunately learned from food recalls, even organic produce can harbor harmful foodborne pathogens. It’s really about looking at the net benefit.
The Environmental Protection Agency and the Food and Drug Administration have long offered guidance on best choices, good choices and choices to avoid when it comes to seafood. While this guidance is primarily aimed at individuals who are pregnant, might become pregnant, or are breastfeeding, as well as for children aged 1 to 11, we can all benefit from it. If you’re concerned about making sustainable seafood choices, the Monterey Bay Aquarium’s Seafood Watch program is a go-to resource.
While fish is a source of many important vitamins and minerals, discussion of its health benefits often focuses on its omega-3 fatty acids, DHA and EPA. There is a plant-based omega-3 fatty acid, ALA (walnuts and flaxseeds are good sources), that has its own health benefits, but most people’s bodies don’t convert much of it into the EPA and DHA that’s especially important for prenatal and childhood brain development.
Some people who don’t like fish may turn to omega-3 supplements, either from fish or from algae, but not only has research found that fish oil doesn’t have the same benefits as eating fish — possibly because there’s a synergistic effect of omega-3s plus other components in fish — research has also found that far too many fish oil and algae oil supplements are oxidized (rancid), which negates their health benefits.