DEAR DOCTOR K:
Are the benefits of juicing as great as I’ve heard?
Juicing — extracting the juice from fresh fruits and vegetables — appears to be the latest trend for anyone looking to detoxify, lose weight or just get healthy. But does research support the claims that juicing can reverse chronic disease, jump-start weight loss and “detox” the body?
First, let’s discuss “extreme juicing.” To cut to the chase, I don’t know of any evidence that justifies a juice cleanse or a fast in which a person drinks only juice for several days to months. Particularly if you do it for more than a few days, you could be getting insufficient amounts of protein and other nutrients.
Now let’s talk about juice. A juicing machine removes the pulp of fresh fruit and vegetables and extracts the juice. Fresh juice has been shown to have advantages over commercially packaged juice — even those that claim to be “all natural” or have no added sugars. So if you’re going to drink lots of juice, it’s best to prepare it at home, from fresh fruits and vegetables.
You can safely store fresh juice up to 24 hours in an airtight container in the refrigerator, but it’s best to drink the juice immediately, before it gets contaminated with bacteria.
Fruit and vegetable juices certainly have some possible health benefits. For example:
- Kale juice may improve cholesterol levels.
- Tomato juice contains plenty of lycopene, a powerful antioxidant that may lower cancer risk.
- Citrus-based juices and carrot juice may reduce heart disease risk.
But juicing removes the skin and insoluble fiber from fruits and vegetables. Consider this:
- The vitamin, mineral and antioxidant content of a whole fruit, like an apple, is decreased significantly when you peel the skin.
- Insoluble fiber can promote bowel regularity, lower cholesterol, stabilize blood sugars and promote a sense of fullness. But insoluble fiber is lost in the juicing process.
- Drinking too much juice may cause weight gain.
- Excessive juice intake can be dangerous for people with diabetes because juice is a concentrated source of calories, primarily sugar.
A few words about detoxifying: What “toxins” are supposedly being removed from your body? How is juicing supposed to remove them? What’s the evidence that it works? None of the websites advocating juicing that I’ve visited answer these questions.
Suppose a person has lead poisoning. I can’t imagine how that toxin, or any other heavy metal, would be removed from the body by juicing. Or when advocates talk about “detoxifying,” do they mean that the treatment washes “bad bacteria” out of the gut? There surely can be bad gut bacteria, but what’s the evidence that juicing eliminates them?
I have nothing against drinking freshly prepared juice from vegetables or fruits as part of a healthy diet. However, I think it would be better for your health to eat lots of fruits and vegetables every day — unjuiced.
(This column ran originally in October 2013.)