What can I do to help prevent flatulence from beans?

In fact, soaking helps reduce the flatulence-causing sugars and starches. See this answer, for example. Soaking alone won't completely neutralize the problem, though. Certain spices may help; according to Wikipedia:

Many herbal substances have been observered since antiquity for reducing flatulence, particularly gas from eating legumes. Cloves, cinnamon, and garlic are potent in reducing gas. The potency of garlic increases when heated, whereas the potency of cinnamon decreases. Other spices have a smaller effect in reducing gas, including turmeric, black pepper, asafoetida and ginger.

Another possibility is to take an enzyme supplement like beano to break down the starches before they get to the large intestine. See Wikipedia for more info.

The effect in question is caused by the high content of oligosaccharides--short sugar chain molecules--in beans. Humans lack the enzyme to digest these, and so they reach the large intestine intact, where resident bacteria eat them producing gas. Therefore, there are two ways to mitigate the effect:

1. Remove the ogilosaccharides
2. Provide the enzyme

This paper from the Pakistan Journal of Nutrition says, in regards to the Seker bean (a legume variety from Turkey), emphasis added, tells us the most effective way to remove the oligosaccharides:

The highest removing, to the extent of decrease up to, approximately, 70% was achieved by soaking in 0.5 % sodium bicarbonate solution for 18 hour followed by cooking in pressured kettle. These conditions could be recommended to remove undesirable [oligosaccharide] contents of the Seker bean used for culinary purposes.

The underlying science should be extremely analogous for any bean. Note the three techniques:

1. Using a tiny amount of baking soda to decrease pH
2. Long soaking (and then discarding the soaking liquid)
3. Pressure cooking

However, they suggest that the consumer may wish to use simple plain water, and accept a higher level of flatus, because the above method will also further reduce the the availability of Vitamin B contents, especially thiamin and riboflavin.

Per The Accidental Scientist, you may also wish to (among their other suggestions):

Try an over-the-counter digestive aid, such as Beano, which contains the sugar-digesting enzyme that the body lacks. Use Beano just before eating so it can break down the gas-producing oligosaccharides. It has no effect, however, on gas caused by lactose or fiber.

I've found it helps reduce gas (and also tastes good) if I add one or more of the following:

• Fresh ginger
• Cumin seed
• Fennel seed
• Coriander seed

The seeds can be ground or whole. Obviously, either way you need to season them by lightly toasting or frying.

(Adding these spices for this purpose is actually common in traditional Chinese and Indian "medicinal" cooking. Works well for cabbage too.)

Asafoetida is antiflatulent.

Asafoetida reduces the growth of indigenous microflora in the gut thereby reducing flatulence.

S. K. GARG, A. C. BANERJEA, J. VERMA. and M. J. ABRAHAM, EFFECT OF VARIOUS TREATMENTS OF PULSES ON IN VITRO GAS PRODUCTION BY SELECTED INTESTINAL CLOSTRIDIA. Journal of Food Science, Volume 45, Issue 6 (p 1601-1602).

From my experience eating beans regularly helps better than anything, after two-three days of at least one dish per day of legumes and I can eat them as any other food with no effects.

I was told that the indigestible membrane round the bean causes flatulence, although other causes are mentioned. Nevertheless, the following works for me.

I par-boil the beans for 20 mins, add lots of cold water and remove the membranes by hand. I do this for butter beans which are the right size for this operation.

One of the best ways that I've seen over the years - actually common in Brazil - is to eat oranges along with your meal. Additionally - putting fresh lemon juice in after the beans are cooked helps tremendously as well. I've been cooking and eating Feijoada for 15+ years and can testify to the efficacy of both.

PS - Lately I've been cooking with organic "Turtle" black beans, which are amazingly easy to digest.

Only way I know is to eat beans often enough to build up the necessary enzymes to overcome the problem. I have heard that eating the beans with rice helps, but I do not suffer from this problem to supply any first-hand information.

One trick that chefs use is to soak overnight and dump the water, rinse and then boil for 10 minutes and dump the water before cooking. This gets most of the indigestible sugars out of the beans.

One recipe for cuban black beans calls for a whole orange to be cooked in the pot with the beans. it has an interesting flavor.

It helps to include plenty of tomatoes.